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Q&A Webinar After Uncategorized

Upgrading historic homes to perform better than new with Deep Energy Retrofits

Ben Allee joined us recently for our  Weekly Wednesday Free CEU webinar Series.

If you missed this session, want to rewatch it, or want to share it with a friend or colleague, you can now do so, as the recording and an article on the topic are available below. 

Attendees learned that deep energy retrofits in historic and multifamily buildings can yield significant energy savings and improved comfort, mainly through advanced insulation, high-performance windows, electrification, and creative problem-solving around challenges like air sealing, ductwork integration, and fire department codes limiting solar panel placement. The webinar highlighted the importance of careful planning, team communication, and flexibility when addressing high costs, tenant relocation, and the technical difficulties of upgrading older building envelopes—especially masonry assemblies. Participants gained new insights into innovative materials such as wood fiber insulation, strategies for isolating basements outside the thermal envelope, and exterior-mounted ERV ducts, as well as the value of considering embodied carbon and post-retrofit occupant behavior. Overall, the session demonstrated that, despite the complexities, thoughtful design and collaboration can make deep retrofits feasible and highly effective, with benefits extending beyond energy savings to occupant satisfaction and preservation of historic structures.

Please help us keep these webinars and writings going by becoming a supporting GHI member or by making a donation. 

This article explores a comprehensive deep energy retrofit (DER) of a historic 1880s townhouse complex in Boston’s Alston-Brighton neighborhood. The project demonstrates how existing buildings can be transformed to meet or exceed the performance of new construction in energy efficiency, occupant comfort, and health, all while reducing embodied carbon and preserving affordability. The approach, methods, challenges, and results are discussed with an eye toward replicability for housing professionals, builders, and contractors. A Q&A section at the end addresses common queries raised during the project’s presentation.

Upgrading Historic Homes to Perform Better Than New: Deep Energy Retrofits in Practice

Rising construction costs and the urgent need to address climate change have placed a premium on the preservation and performance improvement of existing housing stock. Increasingly, deep energy retrofits (DERs) have emerged as a powerful solution, offering not only significant reductions in energy use and carbon emissions but also enhanced comfort, health, and resilience for residents. This article presents a case study of a DER applied to a set of ten adjoining townhouses, originally built in the 1880s, demonstrating how well-designed retrofits can rival—and sometimes outperform—new construction.

Project Background and Goals

The project was initiated by a community development corporation (CDC) with a clear mandate: decarbonize all properties by 2040, a full decade ahead of Boston’s carbon neutrality target. This ambitious goal was driven by both policy (notably the city’s Birdo Law) and a commitment to resident health and comfort. The townhouses in question consisted of 20 units, 75% of which were income-restricted, and the remainder market rate. All had gas heating and hot water, with decentralized hydronic baseboard systems, no central air conditioning, and limited ventilation.

The retrofit aimed to fully electrify the buildings, maximize energy efficiency, minimize disruption to residents, and serve as a model for similar projects across Boston and beyond. The project also prioritized replicability, leveraging existing funding streams and developing construction strategies that could be adopted elsewhere.

Funding and Policy Environment

Boston and Massachusetts offer a robust landscape of green funding, from the City of Boston Retrofit Fund to state programs and green grants. These resources were crucial for the project’s $5 million budget—approximately $250,000 per unit—including contingency and solar installations. Access to such funding is a critical driver for DERs, underscoring the importance of advocacy in regions lacking these mechanisms.

Design and Implementation

The retrofitted buildings retained their original square footage, focusing improvements on the envelope, systems, and renewable energy generation. Exterior upgrades included replacing windows and doors, adding a continuous air and thermal barrier, and installing a rain screen with new siding. The assembly featured:

  • Overcladding and structural sheathing with an integral air barrier
  • Five and a half inches of wood fiber insulation (sourced from Europe at the time, as U.S. products were not yet available)
  • Triple-pane windows installed in prefabricated bucks, with careful attention to drainage and air sealing
  • A rain screen system to manage moisture

Interior work was minimized to reduce resident disruption. Upgrades included new appliances, mechanical shafts for ventilation, and targeted improvements to finishes. The project strategically avoided a full gut rehab, focusing instead on methods that would allow most residents to remain in place throughout the process.

Addressing Building Conditions and Challenges

Given the age and previous renovations of the buildings, exploratory demolition revealed multiple layers of siding, minimal but present rot, and opportunities for targeted repairs. The final air barrier was established at the ceiling of the already-insulated basement, with additional EPS insulation applied to the foundation where possible. The complexity of managing tenant relocation and phased construction required careful planning, including the use of designated “hotel units” for temporary resident moves during interior work.

Mechanical Systems and Electrification

The retrofit achieved full electrification with the installation of high-efficiency, widely available heat pumps for both HVAC and domestic hot water. Energy recovery ventilators (ERVs) provided filtered fresh air to all units, while solar photovoltaic (PV) arrays were added to the roofs within the constraints imposed by fire code setback requirements. The approach favored decentralized systems for easier maintenance and repair, utilizing models that were familiar to local tradespeople.

System design was informed by the drastically reduced heating and cooling loads resulting from the improved envelope, allowing for right-sized equipment and minimal ductwork. Some lessons emerged regarding the installation of ERV ducts within the insulated envelope, prompting plans for process improvements in future projects.

Performance Outcomes

The project’s sustainability consultant projected an 81% reduction in energy use intensity (EUI) and a 74% cut in emissions. Actual measured data post-retrofit showed up to 70% energy use reduction across all units, with further offset from the solar array. Notably, the improved envelope and triple-pane windows yielded significant gains in occupant comfort, including reduced noise from the adjacent highway—a benefit not fully anticipated at the outset.

The project did not achieve full Passive House (PHIUS) certification due to budget and practical constraints, but design certification was attained, and unit-level testing confirmed substantial performance improvements. Whole-building blower door tests showed a 60% reduction in air leakage over baseline, and energy savings tracked closely with modeled predictions. The CDC, as utility payer, directly benefitted from the operational savings, highlighting the financial case for such retrofits in income-restricted and multifamily housing.

Resident Engagement and Education

A dedicated relocation consultant facilitated communication with tenants, smoothing the process of phased interior upgrades. Education around new building systems—particularly the benefits of ERV-provided fresh air versus open windows—proved vital in helping residents adapt to and fully benefit from the improvements. Ongoing engagement, including tracking and sharing utility data, supported the project’s goals of transparency and continuous improvement.

Lessons Learned and Replicability

Several key lessons emerged:

  • Early and thorough building audits are essential, especially for identifying hidden damage and air leakage paths.
  • Funding availability is critical; where incentives do not exist, advocacy is necessary to enable similar projects.
  • Communication and education with residents are as important as technical upgrades.
  • Future projects may benefit from a tiered approach, matching intervention levels to available budgets and balancing envelope upgrades with systems replacement.
  • Prefabrication and streamlined design can help control costs, but site conditions and building geometry may limit their applicability.

The project’s replicable methods and transparent sharing of performance data—soon to be part of a national case study—aim to support the broader adoption of DERs in historic and affordable housing.

Q&A: Common Questions and Project Insights

Q: Were alternative insulation or air sealing products considered, especially with concerns about spray foam’s embodied carbon and health impacts? A: All major spray foam applications dated from prior renovations; only minimal spray foam was used for small gap filling during this retrofit. Wood fiber insulation was chosen for the main envelope upgrade. Future projects may further explore lower-impact alternatives as they become more available.

Q: How was resident disruption minimized during construction? A: The project used a phased approach, relocating residents for only two weeks at a time into designated temporary units while interior work was done. Communication and education played key roles in managing expectations and transitions.

Q: Why was the basement excluded from the primary thermal envelope? A: The basement, already insulated at the floor level from a previous renovation, was left outside the main envelope to balance cost, complexity, and performance. The space is tempered to prevent freezing but not fully conditioned, and foundation and water management repairs addressed prior moisture issues.

Q: Was plug load or appliance-level energy monitoring implemented? A: Utility monitoring occurred at the building and unit level, managed by the property manager. More granular plug-level monitoring would be beneficial but was not implemented in this project.

Q: Did the project leverage historic or low-income housing tax credits, or other incentives? A: Multiple sources were tapped, including the City of Boston Retrofit Fund, state DER incentives, and green grants. Historic tax credits and low-income housing tax credits through QAPs were part of the broader funding landscape considered.

Q: How did the project address code requirements and best practices for ventilation, such as ERV duct separation? A: Each unit’s ERV system was designed to prevent cross-contamination, with supply and exhaust vents for each kept separate per code. Careful planning ensured compliance with recommendations including the 10-foot separation where needed.

Q: Were ground source heat pumps considered? A: Ground source heat pumps were evaluated but ultimately not pursued due to past issues with similar systems and a strategic shift toward air-source and air-to-water heat pumps, which offered greater reliability and cost-effectiveness for this context.

Q: What about the maintenance of the rooftop solar array, especially in winter? A: While no formal snow removal plan was established, the accessible layout allows for maintenance if needed. Energy production is monitored, and drops in output would prompt investigation, including snow removal.

Q: Were environmental health risks like lead or asbestos addressed, considering residents remained in place? A: Environmental testing and remediation were completed prior to the retrofit. Contractors followed all required safety protocols to ensure resident health during construction.

Q: Could similar results be achieved at lower cost, or is $250,000 per unit the new normal? A: Lessons from this and other projects suggest a tiered approach, scaling interventions to budget constraints, can help control costs. For example, prioritizing windows and equipment before full envelope upgrades. However, market conditions and inflation remain significant factors.

Additional Q&A From Speaker After the Webinar

Q: What was the reason for using two layers of exterior sheathing—one layer of plywood with one layer of Zip over?
A: The existing wood plank sheathing had significant cracks and wide gaps, which prevented the application of a self-adhering air barrier membrane. While self-adhered membranes were used on other projects with sound or easily repairable sheathing, this building’s poor condition required a different approach. The structural engineer mandated the installation of ZIP sheathing to reinforce the wall assembly and provide a stable substrate for anchoring the new siding and exterior insulation.


Q: Were tenants’ belongings moved out for the 2-week period of interior renovation?
A: Yes, all units were completely cleared. Tenant belongings and furniture were moved to temporary off-site storage for the duration of the interior renovation to allow for easy access to all areas.


Q: Did you hire cleaners before moving tenants back in?
A: Yes, the contractor hired a cleaning subcontractor to clean the units before the tenants moved back into their renovated units.


Q: Did any of your funding sources include historic tax credits or low-income housing tax credits?
A: The funding sources are outlined in the presentation.


Q: Why was spray foam used in the wall cavity, especially closed cell spray foam, instead of batt insulation?
A: All cavity spray foam was existing and installed as part of earlier renovations in the early 2000s.


Q: What processes were used to educate the public and tenants, and how were insurance issues with public on site addressed?
A: Public outreach included construction tours throughout the DER process, visits arranged for local sustainability organizations, and YouTube videos shared on social media. Hano Homes will also be featured as a case study on the Retrofit Canada platform and with the City of Boston. The client provided personalized training sessions for tenants on operating their unit-specific MEP systems.


Q: How were moisture issues with basement walls addressed, given this is typical for old homes?
A: The retrofit addressed existing basement moisture issues without exterior excavation, which was ruled out due to budget constraints. Instead, obstructions in downspout drainage were cleared, and cracks and gaps across the stone and brick foundation walls were sealed both above grade and on the interior face below grade.


Q: Why not use geothermal HVAC for additional savings, and was a portable drill considered for installing loops in the basement due to limited exterior space?
A: Air source heat pumps were selected as the most cost-effective HVAC solution as designed by the mechanical engineer. Due to negative experiences with geothermal systems on previous projects, geothermal HVAC solutions are generally avoided by the company.


Q: Were there any performance issues with the ERV run on the exterior, such as heat loss or condensation, given about 1″ of rigid insulation over the ducts?
A: No performance issues have been reported. The ERV draws in fresh air and exhausts stale air, with heat transfer occurring strictly within the exchanger core located in the tempered basement space. The system was designed by a mechanical engineer experienced in mitigating condensation risks, and duct insulation exceeded code requirements.


Q: Will the solar PV system be tied into individual tenant electric meters?
A: A meter is installed in the basement of each paired duplex to monitor its PV system performance. The solar contractor tracks output across the full array and provides reporting data to the client to satisfy funding criteria.


Q: Has any post-retrofit consumption analysis been done?
A: The slides at the end of the presentation detail actual energy consumption for select summer and winter months. With nearly a full year of operation complete, findings are planned to be published on the website.


Q: Did you go through MassSave for incentives, and how were savings quantified?
A: The project did receive MassSave funding. SCI (the project Phius verifier) conducted baseline and projected cost and energy use analysis to quantify savings for the DER.


Q: What were the considerations that led to the basement being excluded from the thermal envelope?
A: The basement ceiling had been insulated during a prior renovation, so modifying it fell outside the scope of work. Budget constraints required prioritizing other areas. Both options were evaluated in WUFI, but perimeter demolition and air sealing at the sill plate would have been beneficial for air change performance.


Q: What environmental health regulations came into play, especially regarding lead and asbestos testing or remediation with the site occupied during construction?
A: Lead, asbestos, and radon testing and mitigation were addressed during the previous renovation in 2003. During demolition, the contractor followed industry standards as well as IAP and Phius guidelines.


Q: Was there enough ambient heat for the water heaters during winter months?
A: The basement has sufficient ambient heat for the HPWH to operate, but lower temperatures can reduce efficiency. A small electric heater was installed to maintain a minimum basement temperature above 50°F to protect equipment and prevent freezing. Per manufacturer recommendations, venting cold exhaust air outdoors during winter provides the most efficient operation.


Q: Why use Zip sheathing over existing sheathing instead of a self-adhered or mechanically fastened WRB?
A: The existing wood plank sheathing had significant cracks and gaps, making it noncompliant with manufacturer guidelines for installing a self-adhering air barrier membrane.


Q: At ~$250K per unit cost, have you identified ways to achieve lower per-unit costs with the same or better results for future projects?
A: Achieving the right balance between cost and energy performance is essential in deep energy retrofits. A three-tiered decision-making framework is being developed to help clients evaluate trade-offs. Retrofits can be implemented in phases to secure the highest efficiency gains first. Unique building conditions may reveal additional savings opportunities, and future projects could lower costs by using panelized wall systems or prefabricated window bucks.


Q: For the ERV, vents for fresh and exhaust air appeared close together. Was that a code issue for recirculation, considering PHIUS recommends 10′ separation?
A: The mechanical engineer adhered to PHIUS guidelines and applicable building codes for separating supply and exhaust vents. Ducts in close proximity consist of paired supply or exhaust ducts from individual unit ERVs.

Key Takeaways

  • Deep energy retrofits can transform historic multifamily housing to meet or exceed new construction standards in energy, comfort, and health.
  • Careful planning, phased construction, and clear resident communication are critical for occupied rehabs.
  • Robust funding mechanisms and policy support are essential for widespread adoption of DERs.
  • Comprehensive building audits and flexible, replicable construction approaches help manage risk and cost.
  • Full electrification and right-sized, familiar systems support operational savings and ease of maintenance.
  • Resident education and engagement drive successful outcomes and lasting performance improvements.
  • Measured performance data is vital for validating results and informing future projects.

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Q&A Webinar After Uncategorized

What we learned from 10,000 onsite inspections to improve documented home performance – article

Patrick Nachlas & Audun Meinich, joined us recently for our  Weekly Wednesday Free CEU webinar Series.

If you missed this session, want to rewatch it, or want to share it with a friend or colleague, you can now do so, as the recording and an article on the topic are available below. 

Attendees of the webinar gained valuable insights into the evolving landscape of home energy rating and inspection, with a particular focus on the integration of digital tools like the Ekotrope software and the Onsite app. Many participants learned for the first time about these innovative platforms and how they streamline the documentation and reporting process for HERS raters and builders. There was a strong emphasis on the complexity of gathering and organizing comprehensive photo documentation, with many surprised by the sheer number of photos typically required—often around 22 to 25 per inspection, and even more for energy star audits. The introduction of AI-powered features, such as automatic reading of model numbers and pre-population of inspection forms, was highlighted as a major advancement, promising significant time savings and improved accuracy in report generation.

Please help us keep these webinars and writings going by becoming a supporting GHI member or by making a donation. 

This article explores the critical role of documentation and verification in improving home performance, drawing on insights from over 10,000 onsite energy inspections. The discussion focuses on lessons learned, best practices, and the evolving technology landscape, particularly the integration of Ecotrope’s inspection tools. With a dual emphasis on technical rigor and accessibility, the article is designed for housing professionals, builders, and contractors, as well as the interested public. The narrative highlights how thorough documentation not only supports compliance and certification, but also streamlines workflows, reduces liability, and enhances communication among project stakeholders.

The Importance of Documentation in Home Performance

In the modern landscape of residential construction and renovation, the old adage “trust, but verify” is more relevant than ever. The need to ensure that a high standard of work is maintained, even after walls are closed up and systems are hidden from view, has made third-party verification and comprehensive photo documentation essential practices. These tools underpin not just quality control, but also compliance with codes, green building certifications, energy ratings, and insurance requirements. Furthermore, they serve as vital protections against liability and form the backbone of home energy rebate programs.

At the heart of this process is the recognition that documentation and verification are not mere bureaucratic hurdles. Instead, they are powerful mechanisms for transparency and accountability. When a project is thoroughly documented, every stakeholder—from the builder to the homeowner—gains confidence in the finished product. This is especially true in an era where sustainability and energy efficiency have become key priorities, and programs like LEED, Energy Star, and HERS demand rigorous oversight.

Evolving Challenges in Field Verification

The process of certifying a green building or securing a LEED designation is multifaceted. Minimum energy performance requirements, such as those set by ENERGY STAR, must be met and documented at every stage of construction. This includes the installation of certified appliances, proper ductwork, and ventilation systems. Verification is not a one-time event, but an ongoing process that spans from the slab through to mid-construction and finally to project completion.

Communication between raters, builders, and other professionals is critical. Deficiencies—such as improperly installed bath fan ducts—can compromise the entire ventilation system. Clear, detailed documentation, including photographs, ensures that issues are identified, communicated, and rectified promptly. This not only satisfies certification requirements but also provides a robust record for future reference, warranty claims, or renovations.

Documentation as a Value-Added Asset

Thorough documentation transcends compliance. For homeowners, it serves as a window into the hidden aspects of their home, offering peace of mind and a reference point for future upgrades or repairs. For builders and subcontractors, it provides a layer of protection against liability and disputes, demonstrating that work was completed to standard. The homeowner manual, required under LEED’s Energy and Atmosphere category, exemplifies how documentation can be leveraged for both regulatory and practical purposes.

In the context of additions or major renovations, having an organized archive of construction photos and reports can save considerable time and resources. It allows for informed decision-making and minimizes the risk of damaging existing systems or structures. This approach represents a shift in mindset: documentation is not just a necessity, but a strategic asset for all parties involved.

The Workflow of Onsite Inspections

Energy raters and field inspectors face a complex workflow, often involving multiple software platforms for modeling, data collection, photo management, and reporting. Prior to recent technological advances, this fragmentation resulted in inefficiencies and repetitive tasks. Inspectors would collect photos, upload them to cloud storage, prepare site reports, and communicate findings to builders and office-based modelers—each step requiring manual intervention and creating opportunities for error or omission.

Modelers, in turn, would sift through unorganized folders of photos to verify field data and update energy models. Quality assurance professionals (QADs) would further review all documentation, double-checking that every required item had been captured. Time and energy were often expended not on improving home performance, but on chasing down missing information and resolving discrepancies.

Innovations in Field Data Collection: Ecotrope Onsite

To address these challenges, integrated solutions like Ecotrope Onsite have emerged. Designed in collaboration with industry professionals, this inspection application streamlines the entire process by directly connecting field data collection with energy modeling software. The result is a more seamless flow of information from the job site to the final report.

With Ecotrope Onsite, inspection forms are pre-populated with project-specific data, reducing the need for inspectors to juggle multiple documents or digital tools. Photos taken during inspections are automatically organized, tagged, and uploaded to the central project file. Required fields prompt inspectors if any critical photos or data points are missing before the inspection can be finalized. This not only saves time but also ensures that no detail is overlooked.

The system supports offline operation, a crucial feature for job sites with limited connectivity. Once connected, all information is synced, and the energy model is updated accordingly. Modelers and QADs benefit from immediate access to organized, searchable photo libraries, greatly simplifying the verification process. Builders receive automated reports, closing the feedback loop and facilitating timely corrections when needed.

Lessons from 10,000 Inspections

Analysis of data from more than 10,000 inspections and 250,000 photos has revealed significant variability in documentation practices across the industry. Some companies prioritize speed and capture only the minimum required features, while others aim for exhaustive documentation, sometimes exceeding 100 photos per inspection. This diversity reflects different business models, client expectations, and approaches to risk management.

Tagging and organizing photos emerged as a more complex and valuable task than initially anticipated. Properly categorized photos not only aid in verification but also support efficient audits, warranty claims, and future renovations. The most common types of photos include general documentation, equipment/model numbers, proof of onsite presence, and problem flagging. Notably, the majority of images are for documentation, with a smaller but critical fraction devoted to flagging deficiencies.

Program requirements also drive documentation volume. For example, ENERGY STAR inspections typically demand 33% more photos than standard HERS inspections, reflecting higher standards and additional verification points. The timing and organization of photo collection—often concentrated in the morning hours—illustrate workflow patterns and opportunities for further process optimization.

Automation and the Role of Artificial Intelligence

The future of field verification lies in automation and intelligent data processing. One of the most labor-intensive aspects of inspection is recording long, error-prone equipment model numbers. Ecotrope Onsite is now leveraging AI to extract model numbers directly from photos, reducing manual data entry and minimizing mistakes. This functionality is further enhanced by direct integration with the AHRI database, ensuring that efficiency metrics are accurate and up-to-date.

AI-driven quality assurance tools are also on the horizon. These systems can verify that photos match their intended subject (e.g., confirming a blower door setup), flag blurry or misoriented images, and provide inspectors with real-time feedback. By automating routine tasks, professionals can dedicate more energy to value-added activities, such as working directly with builders and optimizing home performance.

Customization and Flexibility in Documentation

One of the principal lessons from the field is that no single approach fits every project or company. Builders, raters, and green certification professionals each have unique needs and constraints. Ecotrope Onsite addresses this by allowing full customization of inspection forms, enabling users to add, remove, or adjust data fields as required by different programs or specific project needs.

The system accommodates the documentation of features not directly tied to energy modeling, such as bedroom pressure tests or irrigation system details, which are crucial for certain green certifications. Change management features create an audit trail for model updates, supporting transparency and accountability throughout the construction process.

Challenges and Opportunities in Multifamily and Sampling Projects

While single-family homes remain the primary focus, the industry is also grappling with the complexities of multifamily and sampling-based inspections. Current workflows often require separate address-specific models and individualized photo documentation, which can be cumbersome for large projects. Solutions are evolving to better support these scenarios, and ongoing collaboration with field professionals will be key to meeting these challenges.

Educational and Professional Development Applications

The value of robust documentation extends into training and education. Pre-built templates and customizable forms support new raters entering the field, ensuring that critical features are not overlooked. The system’s flexibility makes it a promising tool for professional development, allowing educators to create tailored exercises and feedback loops that mirror real-world inspection scenarios.

Key Takeaways

  • Thorough documentation and third-party verification are essential for quality assurance, risk management, and regulatory compliance in residential construction.
  • Integrated field inspection tools, such as Ecotrope Onsite, streamline workflows by connecting data collection, photo management, and energy modeling.
  • Automation and artificial intelligence are reducing manual data entry and improving accuracy in documentation, freeing professionals to focus on more impactful tasks.
  • Industry practices in documentation vary widely; customizable tools enable stakeholders to adapt processes to their specific needs and program requirements.
  • Organized, tagged, and accessible photo archives support not only certifications but also future renovations, warranty issues, and homeowner education.
  • Ongoing innovation is addressing the unique challenges of multifamily and sampling inspections.
  • Robust documentation systems are valuable for both field professionals and as educational tools for training the next generation of energy raters and green building experts.

Q&A Discussion

Q: Is location tracking included in photo documentation to ensure that images are taken at the correct site?

A: Yes, every photo taken through the inspection tool is automatically tagged with GPS coordinates and a timestamp, ensuring location and time verification for all documentation. This meets requirements for programs like LEED and provides an additional layer of transparency.

Q: How does the system handle inspections in multifamily and sampling projects?

A: The system is organized around address-specific models, which works well for single-family, townhomes, and attached dwellings. For multifamily sampling projects, workflows are evolving, as not all users generate individual address models at the outset. Current capabilities support customization and tagging by unit or apartment, with further enhancements planned.

Q: Can builders or other third-party professionals contribute documentation directly into the system?

A: While builders cannot directly add photos or data entries, they can receive automated reports and may send documentation to the rater for inclusion. The system also allows for sharing access, should a user wish to extend it to additional team members.

Q: What automation features are currently available, and what are the plans for future development?

A: The current system uses AI to extract equipment model numbers from photos and is expanding into other areas, such as window sticker data and photo quality assurance. Planned features include automated checks for correct image orientation and clarity, as well as broader text extraction and workflow integration.

Q: How can the documentation process be customized to meet different certification standards or project requirements?

A: Users have access to a form builder that allows full control over the inspection template. This enables the addition of fields for green certifications, such as flow rates or specific pressure tests, and supports the documentation of features beyond the energy model.

Q: Can this tool be used in training or educational contexts?

A: Yes, the system is well-suited for educational use, with customizable forms, help text, and template repositories. It offers a practical platform for training new raters or supporting ongoing professional development.

Q: What insights have emerged regarding building science from the analysis of inspection data?

A: While aggregate data on performance metrics like air changes per hour (ACH50) is being shared with clients, the process of extracting broad building science insights is ongoing. The potential exists for these insights to inform both field practice and builder education in the future.

Q: Any learnings on the performance of the buildings based on things like the air sealing approach, building type, etc.?

A: This would require building performance data linked to the inspection data. (Live answered)
 
Q: In your ‘flagging problems to fix’ photo category, what lessons have you learned? Are there any other performance lessons learned or general trends?
A: We haven’t looked into this too much. Currently, a minority of our users note the majority of the action items. As a result, any takeaways would be heavily skewed. I think we can share more on this in the future!
Q: So no occupancy permit until all discrepancies are corrected?
A: That determination is up to the Rater, Builder, and Code Official. We just provide an easy way to raise the flag when something is wrong.
Q: There previously was quite a bit of “mix and match” with systems, and they aren’t always in the AHRI directory. How would AI/ONSITE handle that?
A: It would still be able to read the model number. If there is no AHRI match, then it will be up to the Rater to determine the efficiencies.
Q: Wouldn’t auto upright be an AI function?
A: It could be eventually, but AI often isn’t smart enough to know the correct human orientation to a photo.
Q: It looks like you can rotate the photo on the site. Or do you have to upload it with the new orientation?
A: You can rotate the photo within the ONSITE application.
Q: Any chance a builder could use the tool to verify components on ordering and delivery to avoid rework?
A: Builders can absolutely use ONSITE and build custom forms associated with the inspection tasks they are performing.

Please help us keep these webinars and writings going by becoming a supporting GHI member or by making a donation. 

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Q&A Webinar After Uncategorized

Operational and Embodied Carbon, Together at Last! The MA 100-Home Embodied Carbon Study

Patrick Nachlas & Andy Buccino, joined us recently for our  Weekly Wednesday Free CEU webinar Series.

If you missed this session, want to rewatch it, or want to share it with a friend or colleague, you can now do so, as the recording and an article on the topic are available below. 

The webinar helped attendees understand the crucial difference between embodied carbon (EC) and operational carbon in home construction, emphasizing that while Embodied Carbon is not currently part of the HERS (Home Energy Rating System), it is a significant contributor to a building’s overall carbon footprint—often exceeding yearly operational emissions. Participants learned that materials such as concrete and insulation play a major role in EC, and that new tools, standards, and Environmental Product Declarations (EPDs) are making it more feasible to measure and reduce embodied emissions. The session highlighted that addressing both operational and embodied carbon is essential for a comprehensive approach to sustainability, and revealed that the payback time for EC in new homes can be substantial, leading some to view renovation as a greener option. Many found it eye-opening just how large the EC impact can be, and appreciated real examples, regional differences, and practical methods for incorporating EC into future rating systems.

Please help us keep these webinars and writings going by becoming a supporting GHI member or by making a donation. 

As the focus of sustainable building practices shifts from operational efficiency to a holistic view of a building’s carbon footprint, embodied carbon has emerged as a critical consideration. This article explores the findings and methodology of the Massachusetts 100 Home Embodied Carbon Study, which benchmarked embodied and operational carbon in new residential construction. The study demonstrates how HERS raters and energy modeling professionals can integrate embodied carbon assessment into existing workflows, identifies key carbon drivers in building materials and processes, and discusses how these insights are shaping incentive structures and policy in Massachusetts and beyond. The article is intended for housing professionals, builders, contractors, and the general public who are interested in the future of low-carbon construction.

Introduction: Moving Beyond Operational Carbon

For decades, the primary focus of carbon mitigation in the building sector has been on operational carbon—the emissions generated by heating, cooling, lighting, and powering homes. This emphasis has been driven by tangible benefits such as lower utility bills and improved comfort, and it has led to remarkable gains in energy efficiency through programs like HERS ratings, Passive House standards, and the pursuit of net zero energy homes.

However, as operational carbon is steadily reduced thanks to more stringent codes, electrification, and the decarbonization of electricity grids, a new challenge emerges: the carbon emissions associated with the production and assembly of building materials—the so-called “embodied carbon.” Unlike operational emissions, which accrue over decades, embodied carbon is released up front, before a new homeowner ever switches on a light. These upfront emissions are rapidly becoming a dominant factor in the overall climate impact of new construction.

The Massachusetts 100 Home Embodied Carbon Study was designed to quantify and analyze both operational and embodied carbon in residential projects, providing the first comprehensive North American benchmark that integrates mechanical, electrical, and plumbing (MEP) systems into the embodied carbon calculation. The study’s methodology, findings, and implications offer vital guidance to professionals seeking to address the full lifecycle emissions of homes.

Understanding Embodied Carbon: Scope and Significance

Embodied carbon refers to the greenhouse gas emissions generated throughout the lifecycle of building materials, from resource extraction and manufacturing (cradle) to delivery at the construction site (gate). In the context of lifecycle assessment (LCA), this is typically designated as stages A1-A3. These emissions include the processing of concrete, steel, wood, insulation, and other materials, as well as their transportation and initial installation.

While operational carbon (stage B6) remains important, data from the study confirms that embodied carbon constitutes a significant share of a building’s total emissions. For the average home in the Massachusetts study, approximately 55.5 tons of CO2-equivalent were emitted before the first occupant moved in. By comparison, annual operational emissions for these homes were about 3.1 tons, meaning it takes nearly 18 years of operation to match the carbon footprint incurred during construction.

Globally, embodied carbon accounts for roughly 9% of building-related emissions—a figure that is rising as operational emissions fall due to advances in energy efficiency and the growth of renewable energy. In the U.S. alone, annual embodied emissions from new residential construction are comparable to the total emissions of entire countries such as Austria or Greece.

Why Embodied Carbon Matters Now

The urgency of addressing embodied carbon stems from the time value of emissions. Upfront carbon is released immediately, contributing to atmospheric greenhouse gas concentrations when mitigation is most critical. Delaying action on embodied carbon risks overshooting near- and mid-term climate goals—even as buildings become more efficient in their operation.

Moreover, as codes and practices drive operational emissions downward, embodied emissions become the “next big bar on the chart”—the next frontier for meaningful carbon reduction in the built environment. Builders, designers, and contractors who understand and act on this challenge will be leaders in the evolving landscape of sustainable construction.

Methodology: Integrating Embodied Carbon Assessment into Residential Practice

The Massachusetts study was groundbreaking in several respects:

  • It centered HERS raters as the key workforce for embodied carbon assessment, leveraging their existing expertise in building science and energy modeling.
  • It integrated MEP systems into the embodied carbon calculation, providing a more complete picture of total building emissions.
  • It aligned its methodology with the newly released RESNET 1550 standard, which establishes protocols for embodied carbon data collection and reporting in the residential sector.

Data Collection and Analysis Workflow

Participation in the study was limited to dwelling units registered with RESNET and built between 2023 and 2024 in Massachusetts—a state where over 90% of new homes undergo HERS rating. To streamline the process, the study team developed an “integration sheet” that allowed data from energy modeling software (such as Ecotrope) to be efficiently transferred into BEAM, a free embodied carbon calculator.

HERS raters were trained to supplement their usual data collection with additional inputs needed for embodied carbon analysis, such as material quantities for foundations, partitions, and garage areas that are typically omitted in standard energy models. The study found that approximately 60-70% of the data required for an embodied carbon assessment is already captured during a typical HERS rating, making the additional workload manageable after initial training.

To quantify the emissions associated with each material, the study relied on Environmental Product Declarations (EPDs)—third-party verified documents that specify a product’s global warming potential per unit of measure. Where product-specific EPDs were not available, industry-average values were used.

Key Findings: Embodied Carbon Baselines and Drivers

  1. Average Embodied Carbon: The average upfront embodied emissions for the 100 homes studied was 55.5 tons of CO2e per dwelling. This figure provides a crucial baseline for future policy, incentives, and design improvements.
  2. Operational vs. Embodied Carbon: With operational emissions averaging 3.1 tons per year, the initial 55.5 tons of embodied emissions represent a substantial “carbon debt” that takes nearly two decades to offset through efficient operation.
  3. Variability and Opportunity: The study observed a wide range of embodied carbon results, from as low as 20 tons to as high as 144 tons per home. This variation indicates significant opportunity for reduction through material choices and design optimization.
  4. Key Material Contributors: Concrete emerged as the single largest contributor, responsible for about 40% of embodied emissions, followed by MEP systems (18%) and insulation. Windows, while significant in commercial buildings, were less impactful in the residential context studied.
  5. MEP Systems: The inclusion of MEP systems in the embodied carbon scope is notable. While energy models can often estimate heating and cooling equipment based on capacity and duct area, some components (such as wiring) must be approximated by building size to avoid excessive data collection burdens.
  6. Intensity Metrics: When normalized by building size, the average embodied carbon intensity was approximately 226 kilograms CO2e per square meter, consistent with similar studies in North America.

Workflow Feasibility: Training and Quality Assurance

The study’s approach to integrating embodied carbon assessment within the existing HERS workflow was validated by the experience of 16 raters, whose average time to complete an embodied carbon assessment dropped from over three hours to less than one hour as familiarity increased. While early projects required more effort—especially for homes rated months or years earlier—the expectation is that real-time assessment in tandem with operational ratings will further reduce the burden.

ResNet’s emerging quality assurance protocols for embodied carbon will help ensure data consistency and reliability, mirroring the success of HERS as the “gold standard” for operational energy assessment.

Implications for Policy and Market Transformation

Massachusetts is already embedding embodied carbon reduction into its building code and incentive structures. Builders can earn HERS point adders for using low-carbon concrete or achieving a low-carbon shell, effectively trading modest increases in energy efficiency for substantial carbon reductions in materials. This approach recognizes that embodied and operational carbon are distinct but complementary, and that both must be addressed to achieve true decarbonization.

The study’s findings provide a defensible baseline for policymakers to set targets, utilities to design incentives, and builders to benchmark their performance. As the market for low-carbon materials matures and the integration of embodied carbon assessment becomes routine, substantial reductions are within reach.

Looking Ahead: The Path to Holistic Carbon Accounting

The Massachusetts 100 Home Embodied Carbon Study demonstrates that embodied carbon assessment is both feasible and impactful in the residential sector. By leveraging existing energy modeling infrastructure and workforce, the additional burden is minimized, and the path is paved for rapid adoption as software tools evolve.

The study also highlights the need for clear metrics, robust data, and ongoing training. As embodied carbon becomes embedded in codes, incentives, and green building certifications, builders and contractors will be increasingly called upon to make material choices that balance performance, cost, and climate impact.

The ultimate goal is a holistic carbon index that integrates both operational and embodied emissions, allowing for true “low-carbon” certification of new homes. While this remains a work in progress, the groundwork has been laid for the residential construction industry to play a leading role in climate action.

Key Takeaways

  • Embodied carbon now represents a substantial share of the total carbon footprint of new homes, especially as operational emissions decline.
  • The Massachusetts study provides the first North American embodied carbon baseline that includes MEP systems for residential construction.
  • On average, new homes in the study emitted 55.5 tons of CO2e upfront, with operational emissions of 3.1 tons per year.
  • Concrete is the largest single source of embodied carbon in residential construction, highlighting the importance of low-carbon material alternatives.
  • Approximately 60-70% of data needed for embodied carbon assessment is already collected during standard energy modeling, making integration feasible.
  • Incentives and policy are beginning to recognize embodied carbon, with Massachusetts offering HERS point adders for low-carbon materials.
  • Builders, contractors, and energy professionals will need ongoing training and quality assurance protocols as embodied carbon assessment becomes standard practice.
  • The future of sustainable construction depends on addressing both operational and embodied carbon in a holistic, data-driven manner.

 

Q: Who is updating assumptions on carbon content as production methods improve?
A: The RESNET Carbon Index uses NREL data and assumptions on grid cleanliness over the next 25 years. You can read more about it here.

Q: Is foam an insulation issue versus airtightness in fiberglass properly accounted for?
A: It is not a direct tradeoff. There are many methods to airseal a home. Infiltration rates are accounted for in the operational emissions.

Q: How do ICF homes fare in EC compared to stick-framed homes? Will “green” concrete made from electrochemical/solar electricity cement cut down on its EC contribution in a meaningful way?
A: This was not part of this study. However, we would anticipate any meaningful reduction in embodied concrete emissions would have a substantial impact in the whole home results.

Q: Shouldn’t operational carbon vs embodied be compared “apples to apples”? As shown on the previous slides, the type of building affects the results. Putting all the numbers together might be misleading.
A: No, they are disconnected decision trees. The embodied carbon of the materials selected in a home does not directly correlate to the energy efficiency of the home.

Q: Would this study and EC rating methods be instructive on preserving existing structures (for improved reuse) instead of teardowns, which add yet more carbon?
A: End of life for existing buildings was not included in this study.

Q: What was different in components between high and low embodied carbon projects?
A: Amount of concrete and type of insulation were the two primary contributors.

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HVAC Filter Change Alerts Ignored No more? DIY Smart Filtration is Here Article

Winston Mok, joined us recently for our  Weekly Wednesday Free CEU webinar Series.

If you missed this session, want to rewatch it, or want to share it with a friend or colleague, you can now do so, as the recording and an article on the topic are available below. 

During the webinar, attendees learned about the importance of using high-efficiency air filters (such as MERV 13 or higher) to capture fine particulate matter like PM2.5, which can have significant health impacts if not properly managed. Many participants gained a better understanding of how indoor air quality (IAQ) can often be worse than outdoor air, and that filter appearance alone is not a reliable indicator of filter effectiveness or need for replacement. The session highlighted how filters, even when they look clean, might be clogged and negatively impact air flow and HVAC system performance. Attendees appreciated the clear explanations of MERV ratings, regulatory requirements like California performance labeling, and the relationship between filtration, air flow, and health.

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Maintaining high indoor air quality is essential for both the health of building occupants and the longevity of residential HVAC systems. This article explores the importance of dynamic, smart filtration systems as an evolution beyond traditional static filter schedules. Drawing on a comprehensive presentation by an industry expert, the discussion covers the science of particulate matter, filtration standards, the technical challenges of modern airtight homes, and the real-world performance of smart filtration. The intended audience includes housing professionals, builders, contractors, and the general public interested in sustainable, healthy living environments.

Introduction: The Overlooked Cornerstone of Healthy, Efficient Homes

The greenest home is only as healthy as the air its occupants breathe and the systems that support it. While design, construction materials, and energy efficiency often receive primary focus in sustainable housing, ongoing operations and maintenance—particularly regarding air filtration—are fundamental to realizing the benefits of these investments. With the rise of tighter building envelopes and increasing awareness of indoor air quality (IAQ), the paradigm is shifting from fixed filter replacement schedules to dynamic, responsive smart filtration systems.

The Challenge of Airtightness and Indoor Air Quality

Contemporary building practices emphasize airtight construction to maximize energy efficiency. While this approach is effective for controlling thermal losses and gains, it inadvertently compounds IAQ challenges. Pollutants generated internally or infiltrating from outdoors tend to linger, with limited passive air exchange to dilute their presence. As a result, occupants of airtight homes face heightened exposure to airborne threats, particularly fine particulate matter (PM2.5), unless active mitigation strategies are in place.

Traditional HVAC systems are generally “blind” to these acute pollution spikes. They cycle based on temperature or preset schedules, without the ability to sense or react to real-time changes in air quality. This creates a paradox: as homes become more energy efficient and comfortable, the risk of indoor pollutant accumulation increases, unless ventilation and filtration strategies evolve accordingly.

Understanding Particulate Matter and Its Health Impacts

Central to the discussion of smart filtration is particulate matter, specifically PM2.5—particles with a diameter of 2.5 microns or smaller. These microscopic pollutants can originate from both outdoor sources (such as wildfire smoke, vehicle emissions, and industrial activity) and indoor activities (like cooking or burning candles). PM2.5 is especially concerning because it penetrates deeply into the lungs, readily entering the bloodstream, and can persist in the body for months.

Exposure to elevated levels of PM2.5 is linked to cardiovascular stress and other adverse health effects, especially for sensitive populations such as children, the elderly, and those with respiratory conditions. The Environmental Protection Agency (EPA) recognizes poor air quality as a significant threat, noting that Americans spend the majority of their time indoors, further elevating the importance of effective IAQ management.

Sources and Patterns of Indoor Air Pollution

Within homes, common activities such as cooking—especially high-temperature and searing methods—can cause dramatic spikes in PM2.5. Air quality monitors reveal that such spikes occur rapidly and dissipate slowly, particularly in airtight environments. The EPA’s air quality rating system, adapted for indoor spaces, indicates that levels above 100 on its index are considered unhealthy for sensitive groups, with wildfire events often pushing levels into hazardous territory.

Filtration Fundamentals: MERV Ratings and Pressure Drop

Mitigating PM2.5 exposure relies heavily on effective air filtration. The Minimum Efficiency Reporting Value (MERV) rating, developed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), is the industry standard for measuring filter performance. MERV ratings indicate a filter’s efficiency at removing particles across three size ranges: 0.3–1 micron, 1–3 microns, and 3–10 microns.

  • MERV 8: Common in residential and commercial settings. Effective for larger particles (pollen, dust) but not for PM2.5 or smaller particles that impact health most significantly.
  • MERV 11 & 13: Increasingly adopted, especially after the COVID-19 pandemic, as they capture a substantial portion of smaller particles, including some viruses and bacteria. MERV 13 is now a strong commercial standard in many states.
  • MERV 16 and HEPA: Correspond with the performance of N95 masks, capturing 95% or more of even the smallest particles.

Pressure drop (differential pressure) across the filter is a critical, often misunderstood parameter. As filters load with particulate matter, resistance increases, reducing airflow and system efficiency. California’s Title 20 regulation now requires filters to display detailed performance data, empowering consumers and professionals to balance filtration efficacy with energy consumption and system health.

It is a common misconception that higher MERV ratings always entail higher pressure drops. In reality, filter quality and design play significant roles; low-quality filters can have higher resistance irrespective of their MERV rating.

The Role of Room Purifiers vs. Whole-House Filtration

While portable room air purifiers provide a valuable second layer of defense, the central HVAC system remains the foundation of whole-house air quality management. Properly selected filters in the main system can address the entire building, whereas purifiers are most effective for specific rooms or individuals with heightened sensitivity.

Smart Filtration: Components and Operation

Smart filtration represents an advance over traditional, static filter replacement approaches. It comprises four key elements:

  1. Sensing (Eyes): Air quality monitors, preferably using laser-scattering technology, provide real-time measurement of PM2.5 and other pollutants. Responsive monitors with integration capabilities are essential for enabling dynamic system responses.
  2. Control (Brain): Smart thermostats and back-end systems interpret sensor data, running algorithms to trigger filtration only when needed. Integration with home automation platforms—and proper G-wire fan control—allows for precise, on-demand operation.
  3. Air Movement (Brawn): The HVAC system, including the air handler and ductwork, must be capable of responding to control signals and delivering adequate airflow through high-performance filters.
  4. Filtration (Shield): MERV 13 or higher filters are recommended to effectively capture PM2.5 and smaller particles. Selection should consider initial pressure drop and system compatibility.

This integrated approach allows for filtration to occur precisely when poor air quality is detected, minimizing both exposure and unnecessary energy consumption.

Performance Data: Before and After Smart Filtration

Real-world data underscores the value of smart filtration. For example, in modern, airtight homes, a single cooking event can cause elevated PM2.5 to persist for up to 15 hours if left unmanaged. With smart filtration, the same home can return to “green zone” air quality within two hours. Aggregated national data show that homes equipped with smart filtration experience, on average, a 30% reduction in PM2.5 exposure compared to those without.

It is important to note that filter loading rates can vary dramatically based on environmental events (e.g., wildfires, construction dust) and indoor behaviors. Filters can become fully clogged much faster than expected, sometimes in days rather than months, underscoring the need for monitoring rather than relying solely on visual inspections or scheduled changes.

Practical Considerations and Trade-Offs

  • Filter Life and Maintenance: Monitoring differential pressure and actual air quality is superior to fixed replacement schedules. Looks can be deceiving; filters may appear clean yet be fully clogged with fine particles or minerals.
  • Static Pressure Management: Oversized pressure drops can compromise HVAC performance. Selecting high-quality filters and monitoring system parameters ensures both air quality and system longevity.
  • Energy Consumption: Running the HVAC fan continuously is energy-intensive and often unnecessary. Smart filtration enables on-demand operation, maximizing efficiency while maintaining healthy air.
  • Integration Challenges: Not all legacy systems support advanced control (e.g., modulating fans, home automation). Retrofitting may require updates to thermostats or wiring.

Opportunities for Builders, Contractors, and Housing Professionals

Smart filtration systems offer tangible benefits beyond occupant health:

  • Reduced Callbacks: Data-driven maintenance can prevent system failures due to neglected filter changes, protecting contractors from costly warranty disputes and improving customer satisfaction.
  • Enhanced Service Offerings: Maintenance contracts or monitoring services can be enhanced with real-time data, enabling proactive support and differentiated business models.
  • Compliance and Marketability: As regulations and consumer awareness increase, homes with advanced IAQ solutions will enjoy a competitive edge.

Key Takeaways

  • Modern airtight homes require active, data-driven management of indoor air quality to protect occupant health and system performance.
  • 5 is a primary health concern; effective mitigation requires filters rated MERV 13 or higher.
  • Filter life is dynamic and should be monitored using pressure sensors and air quality monitors, not fixed schedules or visual inspection.
  • Smart filtration—combining sensing, control, air movement, and high-efficiency filters—enables on-demand operation, reducing both exposure and energy use.
  • Builders, contractors, and housing professionals benefit from reduced callbacks, enhanced service relationships, and improved market positioning.
  • Room purifiers supplement, but do not replace, the role of whole-house filtration.
  • Ongoing education and awareness are essential as standards, technologies, and expectations evolve.

Q&A: Addressing Common Industry Questions

Q: How does filter effectiveness change as filters become clogged?

A: As a filter loads with particulate matter, its efficiency at capturing smaller particles generally increases, but airflow is reduced. This means less air is being filtered overall, so the net benefit may decline depending on the rate of new particulates vs. rate of removal. New standards (such as MERV “A” ratings) now assess both loaded and unloaded filter performance, including the risk of particle “blow-through” during sudden bursts of airflow.

Q: What about volatile organic compounds (VOCs) and other pollutants besides PM2.5?

A: PM2.5 is best addressed through electrostatic and mechanical filtration. VOCs and CO2, however, are not effectively removed by standard HVAC filters and require carbon, ventilation or dilution (e.g., opening windows, using energy recovery ventilators). Low-cost VOC sensors are relative, not absolute, and should be interpreted with caution.

Q: How do pleat density and filter design affect performance?

A: More pleats generally increase surface area, reducing face velocity and increasing efficiency slightly. However, pleats packed too tightly can restrict airflow excessively. Optimal design balances surface area, media quality, and system compatibility.

Q: How do you match filter performance data to HVAC system specifications?

A: Use the system’s rated airflow (CFM) to select filters using performance charts (such as those required by Title 20). Most systems tolerate a 50% increase from initial static pressure, but specifics vary by model and installation. Always verify available headroom to avoid exceeding system limits.

Q: Can smart filtration systems help contractors and builders reduce warranty claims and improve service?

A: Possibly. Real-time data can be shared (with homeowner permission) to verify maintenance, provide reminders, and resolve disputes about equipment care. This transparency supports better relationships and more reliable system performance.

Q: Are there collaborations with the medical industry or health professionals?

A: While not a substitute for medical advice, cleaner indoor air is associated with reduced health risks. Some health professionals increasingly recommend IAQ interventions (like electrification of stoves or advanced filtration) for patients with respiratory challenges. However, building professionals should avoid making direct medical claims.

Q: What are the main integration or retrofit challenges?

A: Not all HVAC systems support advanced controls or smart thermostats out of the box. Retrofitting may require wiring upgrades (such as adding a G-wire for fan control) or selecting compatible smart home platforms. The market is rapidly evolving to facilitate integration.

Q: What are the metrics behind the AQI Color chart? Are they based on PPM or something else?
A: The EPA’s Air Quality Index (AQI) is a standardized number calculated from the amount of particulate matter (PM) in the air across various sizes. It’s not simply PPM; it’s a composite value representing air quality. More info from the EPA

Q: What rating systems exist for furnace/air filters, and how do 3M’s “MPR” numbers compare to MERV ratings?
A: There are three main standards: MERV, MPR (used by 3M), and FPR. They measure similar things—filter effectiveness at capturing particles—but use different methods and scales. You can convert between them, though the numbers don’t line up exactly. For example, a 1600 MPR is roughly comparable to MERV 13.

Fan Pressure, System Design & Title 20

Q: How do you correlate an air handler’s maximum fan pressure rating (from the data plate) with the Title 20 filter chart?
A: Title 20 provides baseline tests at various air speeds, allowing for apples-to-apples comparisons of filter efficiency. Your air handler will operate somewhere within that range, depending on its fan speed(s). Title 20 doesn’t directly indicate if your system is properly specified or facing issues; it’s more of a comparative tool.

Filter Performance Over Time

Q: How does the effectiveness of a MERV 13 (or similar) filter change as it becomes more soiled?
A: Filtration efficiency actually increases as the filter collects more particles, but this also increases the filter’s pressure drop, potentially reducing airflow. It’s a tradeoff between better filtration and reduced air movement.

Q: When you push clean air through a dirty (virus?) filter, does it still keep your air clean?
A: Yes, a dirty filter will continue to capture particles—often even more effectively as it loads up—but at the cost of higher pressure drop and reduced airflow.

Filter Types: Mini-Pleat vs. Traditional Pleat

Q: How does a mini-pleat filter compare to a traditional pleat filter?
A: Filters with mini-pleats (e.g., a 7.3mm pleat pitch vs. 25.4mm) have a much larger surface area—about three times more than traditional filters. This allows for lower pressure drop even with more restrictive, high-efficiency media like MERV 13 or above.

Q: Manufacturer claims “2.5X the pleats for higher efficiency” on mini-pleat filters. Is this accurate?
A: Increased pleat density does increase surface area and can improve efficiency and reduce pressure drop, but the benefit also depends on the filter media quality. It’s generally true, but case dependent.

Q: How are ERVs (Energy Recovery Ventilators) integrated into smart filtering schemes, especially if they’re only nominally filtered?
A: Integration can vary by system. Some resources, such as this video, explain methods. Generally, smart filtration schemes monitor air quality and dynamically control fans and filtration based on current needs.

Q: In Vermont and similar climates where ventilation runs 24/7, how does smart filtration fit in?
A: HVAC systems may run at different speeds; some run continuously at low speed, others cycle on/off. Smart filtration can ramp up fan speed in response to poor air quality events, but the approach depends on system specifics.

Q: Does smart filtering take into account CO₂, VOCs, etc., or just PM2.5?
A: Smart filtration alone may not address CO₂ or VOCs. Effective indoor air quality (IAQ) management includes monitoring for these gases and using ventilation (fresh air exchange) as needed. The key components are:

  1. Monitoring air quality,
  2. Dynamic control,
  3. Moving air where needed,
  4. Venting or filtering contaminants.

Q: If you only monitor for PM2.5, are you missing issues with CO₂ or other contaminants?
A: Potentially, yes. Many air quality monitors track PM2.5, CO₂, and VOCs. Standard HVAC filters don’t capture CO₂ or VOCs, so addressing those requires ventilation—opening windows or running outdoor air exchange systems.

Q: Is VOC filtration a missing link in IAQ?
A: Removing VOCs is challenging. While some filters include carbon to capture VOCs and odors, most lack enough carbon to be effective throughout their lifespan. Introducing outdoor air is the most common way to reduce indoor VOCs.

System Operation & User Experience

Q: How does filter effectiveness relate to air system operation? For example, running the blower 10 minutes out of every 30 without a smart thermostat?
A: Filtration only works when air flows through the filter. Even simple cycling (e.g., 10 minutes on, 20 off) can be effective at reducing particulate levels, with PM2.5 levels dropping quickly after air circulation resumes.

Q: How do electrostatic filters work compared to standard filters?
A: Electrostatic filters charge incoming particles, capturing them regardless of size. This method doesn’t rely on fine mesh to block particles.

Ductwork & Particulate Distribution

Q: Does air PM distribute evenly in a space based on height? Should return air registers be placed at specific elevations for effective filtering?
A: Generally, air movement dominates over gravity in distributing particulates, so PM does not have a noticeably uneven vertical distribution. Register height can have minor efficiency effects, but many other factors play a larger role.

Conclusion

Smart filtration represents a critical advance in the pursuit of healthy, sustainable, and efficient homes. For housing professionals, builders, and contractors, understanding and implementing these systems provides a powerful means to safeguard occupant wellbeing, protect investments, and differentiate in a competitive marketplace. As indoor air quality becomes an increasing priority, dynamic, data-driven approaches will be the cornerstone of best practices in residential building performance.

For further information on indoor air quality and smart filtration, visit the Green Home Institute’s website and access additional resources on sustainable building practices.

Key Takeaways

  • Airtight homes require active IAQ management to prevent pollutant buildup.
  • 5 is a major health risk best mitigated by high-quality, high-MERV filters.
  • Filter life varies with conditions—monitoring is superior to fixed schedules.
  • Smart filtration delivers on-demand, efficient, and effective air cleaning.
  • Data-driven maintenance benefits both occupants and industry professionals.
  • Room purifiers are supplementary; whole-home systems are foundational.
  • Proper integration and education are crucial for optimal performance.
  • Ongoing adaptation to standards and technology is essential for success.

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Basics of Electric Fireplaces for Aesthetics and Health – Article

Carl Brekjern, joined us recently for our  Weekly Wednesday Free CEU webinar Series.

If you missed this session, want to rewatch it, or want to share it with a friend or colleague, you can now do so, as the recording and an article on the topic are available below. 

Webinar attendees learned that electric fireplaces, particularly the newer water vapor models, offer enhanced options in aesthetics, energy efficiency, and installation flexibility. Many discovered for the first time that water vapor fireplaces use mist to create realistic flame effects, are vent-free, can be installed in various locations—including retrofits of traditional fireplaces—and are available in both canister and plumbed configurations. These fireplaces often use LED lights, operate on either 120V or 240V, and can improve indoor air quality since they produce no combustion or CO emissions, making them suitable for energy-efficient and healthy homes, including Passive House designs. Participants also learned about LEED credits for forgoing traditional fireplaces and noted that, while some electric fireplaces can provide heat, many water vapor models focus on visual effect rather than heating. Overall, attendees appreciated the advancements in electric fireplace technology and aesthetics, though some wished for more in-depth technical information and expertise from the presenters.

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This article explores the health, energy, and design implications of fireplaces in residential construction and renovation, emphasizing the advantages of electric fireplaces. Drawing upon current green building standards, including LEED certification and the electrification movement, the article provides an in-depth look at how electric fireplaces offer a compelling solution for balancing aesthetics, health, safety, and sustainability. Designed for housing professionals, builders, contractors, and the general public, the content delivers a comprehensive overview of fireplace types, installation options, energy use, and practical retrofit guidance, offering actionable insights for both new construction and existing home upgrades.

Introduction: The Significance of Fireplaces in Green Building

The use of fireplaces in homes is deeply rooted in human culture, providing warmth, a focal point for gathering, and a connection to nature that supports mental well-being. Traditionally, the comfort and beauty afforded by wood and gas fireplaces have been accompanied by significant trade-offs, particularly in terms of air quality, occupant health, and environmental impact. As the housing industry evolves with a focus on sustainability and decarbonization, professionals are increasingly tasked with reconciling these historic comforts with modern standards for health, energy efficiency, and environmental stewardship.

Green building certification systems such as LEED for Homes, EPA Indoor Air Plus, and the electrification movement have changed the criteria by which fireplaces are assessed. These frameworks prioritize indoor air quality, carbon emissions reduction, and occupant safety, often challenging traditional methods of combustion heating. Within this context, electric fireplaces have emerged as a transformative solution, offering both the aesthetic and psychological benefits of fire without the drawbacks of combustion emissions.

Fireplaces and Green Certification Standards

In green building programs, the inclusion and design of fireplaces are regulated by prerequisites and bonus credit opportunities. The LEED for Homes standard, for example, places combustion venting under the Environmental Quality (EQ) prerequisite, which governs not only fireplaces but also furnaces and water heaters. While much of this regulation focuses on safety measures—such as backdraft prevention, combustion air supply, and sealed enclosures—the underlying goal is to eliminate or drastically reduce indoor and outdoor pollution.

LEED and similar programs encourage the replacement of natural draft units with sealed combustion or power-vented alternatives. Projects are required to undergo rigorous testing, such as the BPI or ResNet Combustion Safety Backdraft Potential Test, to ensure that backdrafting does not introduce harmful pollutants into living spaces. Failure to meet these criteria can result in forfeiture of certification, regardless of other sustainability achievements.

For professionals operating within these frameworks, understanding the compliance pathways and the rationale behind them is essential. The standards prioritize occupant health by minimizing exposure to combustion byproducts, such as carbon monoxide and particulate matter, and emphasize the need for robust ventilation and air sealing. Even when sustainable fuels like bioethanol or biomass are used, the imperative remains: combustion must not compromise indoor air quality.

The Evolution of Fireplace Technology: From Combustion to Electricity

The transition from wood- and gas-burning fireplaces to electric models represents a significant shift in both technology and philosophy. Electric fireplaces offer a number of advantages relevant to the modern home:

  • No Combustion Emissions: Electric fireplaces do not produce smoke, carbon monoxide, or other combustion pollutants, preserving indoor air quality and contributing to a healthier home environment.
  • Energy Efficiency: These units are nearly 100% efficient at the point of use, as all electricity consumed is converted into heat or light, with no losses from venting or flue systems.
  • Design Flexibility: Electric fireplaces are available in a wide range of styles, sizes, and installation modalities, making them adaptable to both new construction and retrofit scenarios.
  • Safety: With no open flame or hot surfaces, electric fireplaces present fewer fire hazards, and built-in safety features, such as overheat protection, are standard.

Green certifications increasingly recognize electric fireplaces as a preferred option. In some cases, omitting a fireplace altogether earns bonus points for simplicity and air quality. However, when the aesthetic and biophilic benefits of a fireplace are desired, electric models provide a means to achieve the best of both worlds: ambiance without adverse health or environmental impacts.

Types of Electric Fireplaces: Features and Applications

Electric fireplaces are offered in a variety of formats, each suited to different design intents and functional needs:

  1. Linear Electric Fireplaces: Modern and versatile, linear models are popular in both residential and commercial settings, including single-family homes, multi-family residences, and condos. They range in size from compact units to large, dramatic installations, and can be wall-mounted or recessed. Many feature customizable flame colors and ember beds, enhancing design flexibility.
  2. Traditional Electric Fireplaces: Designed to replicate the appearance of classic wood-burning fireplaces, these units are available as fireboxes or inserts. They are ideal for retrofitting existing mantels or replacing outdated gas or wood fireplaces, offering shallow depths for easy installation.
  3. Water Vapor Fireplaces: Using ultrasonic technology, these models create a realistic flame effect with illuminated water vapor. They are available as built-in units, linear formats, or movable cassettes, and can be installed with or without glass enclosures. While generally not intended for primary heating, they excel in realism and are particularly suited for applications where flame authenticity is paramount.
  4. Multi-Sided Fireplaces: Three-sided or bay-style electric fireplaces provide panoramic views and are often used as architectural features in open floor plans, dividing spaces while maintaining visibility and ambiance from multiple angles.
  5. Freestanding and Portable Fireplaces: These units offer maximum flexibility, requiring only a standard electrical outlet. They are popular in smaller spaces, guest rooms, or cabins, and can be easily relocated as needs change. Some models combine fireplace functionality with media consoles for added utility.

Advanced features, such as smart home integration, app-based controls, and customizable lighting, are increasingly standard across all types, catering to the expectations of today’s connected consumer.

Installation and Retrofit Considerations

One of the advantages of electric fireplaces is the simplicity of installation compared to combustion-based systems. Wall-mounted units require minimal construction—much like mounting a television—while recessed and built-in models may necessitate modest framing or drywall work. Most electric fireplaces operate on standard 120V household current, though larger models may be wired for 240V to increase heat output. This flexibility allows for both plug-and-play and hardwired configurations, with the caveat that design decisions about voltage should be made early in the project to avoid costly rewiring.

For existing homes, electric fireplace inserts are an effective means to retrofit outdated or unsafe wood and gas fireplaces. The process typically involves framing the opening, ensuring proper electrical supply, and, where appropriate, sealing off old vents and chimneys to prevent air leakage and moisture intrusion. These upgrades not only improve safety and energy efficiency but also enhance thermal comfort and the overall aesthetics of the space.

Outdoor-rated electric fireplaces further expand design possibilities, providing the ambiance of fire without the safety and maintenance concerns associated with outdoor wood or gas units. Weatherproof casings and specialized warranties ensure reliability in exposed environments, though it is important to select units specifically designed for outdoor use.

Energy Use and Efficiency: Practical Implications

A central concern for builders and homeowners is the operational cost and efficiency of electric fireplaces. Most models consume between 750 and 1500 watts—comparable to space heaters—but with the added efficiency of direct conversion of electricity to heat. Operating costs typically range from 10 to 30 cents per hour, depending on local electricity rates and whether the heating element or flame-only mode is used. In contrast, gas fireplaces often cost significantly more to operate per hour and produce emissions both inside and outside the home.

Electric fireplaces are particularly well-suited for zone heating, allowing occupants to heat occupied rooms without running a central system. This can lead to energy savings in homes where supplemental heating is desirable. The flame-only mode, powered by LED lighting, offers the visual benefits of a fire with negligible energy use—an important consideration for highly energy-efficient or passive house designs.

For all-electric homes, electric fireplaces integrate seamlessly with renewable energy systems, such as rooftop solar, further reducing their carbon footprint. While not typically designed to serve as primary heat sources, larger units can provide supplemental heat for spaces up to 1,000 square feet, making them useful in a variety of residential contexts.

Health and Safety: Protecting Occupants

Health and safety are at the forefront of green building standards, and electric fireplaces excel in these domains. Unlike combustion-based appliances, they do not release carbon monoxide, nitrogen dioxide, or fine particulates. This makes them especially suitable for households with children, elderly occupants, or individuals with respiratory sensitivities.

The front glass of electric fireplaces remains cool to the touch, reducing burn risk, and built-in overheat protection is standard. Proper installation includes maintaining clearances from furniture and flammable materials, and most manufacturers recommend avoiding extension cords and adhering to dedicated circuit requirements to mitigate electrical risks.

By eliminating the need for fuel storage, venting, or gas lines, electric fireplaces further reduce the complexity and hazards of traditional systems. These advantages contribute to healthier indoor environments and lower the risk profile for both single-family and multi-unit dwellings.

Practical Guidance for Housing Professionals and Contractors

For professionals in the housing industry, the adoption of electric fireplaces offers several strategic advantages:

  • Streamlined Compliance: Electric fireplaces simplify adherence to green building standards and local codes, often eliminating the need for complex combustion venting and air quality testing.
  • Design Versatility: The wide range of styles and installation options makes electric fireplaces adaptable to both new construction and renovation projects, supporting creative architectural solutions.
  • Cost-Effective Retrofits: Replacing old wood or gas fireplaces with electric inserts can be accomplished with minimal disruption, improving safety and energy efficiency while preserving or enhancing the room’s focal point.
  • Enhanced Occupant Satisfaction: By providing the ambiance of a traditional hearth without pollution or maintenance concerns, electric fireplaces contribute to occupant comfort and mental well-being.

Builders and contractors should advise clients to consider future electrical needs early in the design phase, particularly when planning for higher-output units or integrating with renewable energy systems. For retrofits, sealing off old chimneys and vents is recommended to prevent energy losses and moisture problems. Outdoor installations require selection of weather-rated models and attention to warranty limitations.

Key Takeaways

  • Electric fireplaces provide the visual and psychological benefits of a fire without the health, safety, or environmental drawbacks of combustion-based systems.
  • Modern green building standards strongly favor electric fireplaces for their contributions to indoor air quality and energy efficiency.
  • Installation of electric fireplaces is straightforward and flexible, accommodating both new builds and retrofits.
  • Operating costs are low, and electric models are particularly effective for zone heating and all-electric homes.
  • Safety features such as cool-touch glass, overheat protection, and the elimination of open flames make electric fireplaces suitable for a wide range of settings.
  • For retrofitting existing homes, electric inserts are an effective way to upgrade old fireplaces, improve energy performance, and reduce maintenance.
  • Coordination with electrical contractors is advised for larger units requiring 240V wiring.
  • Outdoor electric fireplaces expand design possibilities but require weather-rated models.
 
Q: Do they come with thermostats?
A: Yes.  Most models of electric fireplaces have built in thermostats so the heater will turn off once the desired temperature is reached. 
 
 
Q: What are the cassettes being mentioned?
A: The cassettes mentioned were the Dimplex Opti-Myst fireplaces.  You can have them free standing, build them into a wall or combine multiple units to create a dramatic focal point for the room.
 
 
Q: Where does the heat come from on wall mounted or built in?
A: The heater for most wall mounted and built in electric fireplaces is usually at the bottom of the unit.  Some have them at the top but it depends on the model.
 
 
Q: Is there any consideration of CO sensors to be installed with these?
A: No need for CO sensors.  Electric fireplaces do not create any carbon dioxide emissions.
 

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Urban and Old: Residential Energy Retrofit and Subsequent Savings Article

Marcus de la fleur, joined us recently for our  Weekly Wednesday Free CEU webinar Series.

If you missed this session, want to rewatch it, or want to share it with a friend or colleague, you can now do so, as the recording and an article on the topic are available below. 

What the session was about, according to our live attendees

The webinar provided attendees with practical insights into retrofitting older buildings—especially masonry structures—for improved energy efficiency and comfort. Participants learned about various insulation strategies, including the use of closed cell and open cell spray foam in combination to balance air sealing, vapor permeability, and thermal performance, as well as the importance of moisture management in every renovation step. The session highlighted real-world case studies, detailing how deep energy retrofits can succeed through careful planning, attention to detail in wall assemblies and HVAC choices, and innovative solutions like hexagonal core ERVs for better humidity and energy control. Attendees also became aware of the challenges posed by restrictive building codes, the need for knowledgeable contractors, and the financial considerations of large-scale upgrades. Importantly, the webinar reinforced that user behavior and ongoing maintenance ultimately determine the effectiveness of even the most advanced systems, emphasizing that the key to long-term efficiency lies in both technical choices and how occupants interact with their buildings.

Please help us keep these webinars and writings going by becoming a supporting GHI member or by making a donation. 

Article Based on Webinar*

 

This article explores the comprehensive process of retrofitting a historic masonry residential building for high energy performance and sustainability. Centered on a case study from Chicago’s West Side, it details the technical, strategic, and practical challenges of transforming a turn-of-the-century, multi-unit property into a near net-zero, healthy, and resilient home. The discussion covers building envelope upgrades, mechanical system optimization, moisture management, ventilation, renewable energy integration, and lessons for professionals and the general public aiming to decarbonize older housing stock. The article is intended for housing professionals, builders, contractors, and anyone interested in deep energy retrofits, balancing technical rigor with accessible explanations.

Retrofitting Urban Masonry Housing for a Sustainable Future: Lessons from a Deep Energy Retrofit

The transformation of legacy urban housing into energy-efficient, healthy, and sustainable residences is a critical strategy for addressing both the housing crisis and the urgent need to decarbonize the built environment. Older masonry buildings, which are abundant in many American cities, pose unique challenges and opportunities in this endeavor. Through a detailed case study of a deep energy retrofit of a 1902 masonry two-flat in Chicago, this article illustrates best practices, technical considerations, and real-world lessons for housing professionals, builders, contractors, and engaged citizens.

The Opportunity and the Challenge of Existing Housing Stock

Preserving and upgrading existing housing is vital for reducing emissions, supporting urban connectivity, and meeting rising housing needs. Existing buildings often suffer from excessive energy use, poor air quality, and deferred maintenance—issues that contribute to both environmental and social challenges. At the same time, their embodied carbon and location advantages (such as walkability) make them prime candidates for sustainable transformation.

Yet, the path to high performance in these structures is far from straightforward. Masonry walls, outdated windows, leaky envelopes, and legacy mechanical systems present complex interrelated problems. The case study building, a 4,500-square-foot, three-unit property, exemplifies these challenges but also demonstrates the potential for remarkable improvement through careful planning and execution.

Energy Baseline and the Priority of Envelope Improvements

A rigorous approach begins with establishing a baseline for energy performance. A blower door test revealed that the subject building leaked air at a rate equivalent to a 22-inch by 22-inch open hole in the wall—typical for its era but unacceptable for efficiency and comfort. Energy modeling underscored that space conditioning (heating and cooling) was the dominant energy load, directing focus to the building envelope as the most impactful area for intervention.

Envelope improvements encompassed insulation and air sealing of the basement floor, foundation walls, above-grade exterior walls, windows, doors, attic, and roof. Special emphasis was placed on moisture management, recognizing that improper insulation strategies can lead to condensation, mold, and structural damage. The solution required assemblies that preserved the drying potential of the walls in both directions.

Wall and Roof Assemblies: Technical Solutions for a Historic Masonry Building

The wall assembly selected for the project consisted of a “flash and batt” strategy: a one-inch continuous closed-cell foam layer (carefully chosen for vapor retarder—not barrier—properties), two inches of open-cell foam, and 3.5 inches of rockwool batts within the interior framing. This assembly provided robust insulation (R28-R40, depending on location) and targeted airtightness of 3 air changes per hour at 50 Pascals.

The roof was upgraded with two layers of polyisocyanurate boards above the deck and three layers of rockwool batts below, all air-sealed with drywall and vapor-retarding latex paint. This approach delivered an R-value of 60 while minimizing the risk of cold deck condensation and preserving the roof’s drying potential. The roof assembly also included details such as a dimple mat at the parapet to facilitate vapor venting.

These solutions, developed in 2009, would likely be complemented by even more advanced products today, such as smart membranes and alternative insulation materials. The key takeaway is the necessity of project-specific strategies, tailored to the building’s physical characteristics and performance goals.

Air Tightness and Windows: The Details That Matter

Air sealing was an exercise in diligence, requiring the building to be gutted to its masonry shell. All thermal bridges and penetrations were addressed, with deferred maintenance issues uncovered and resolved. The result: air exchange rates dropped dramatically from 13.9 to 0.62 air changes per hour at 50 Pascals—far exceeding the initial target and fundamentally improving comfort.

Window selection and installation are critical in high-performance retrofits. The project specified triple-glazed, airtight windows (0.2 cfm/sf or less), with a mix of fixed casement and awning styles to minimize air leakage and maximize manual ventilation options where needed. Installation was performed with meticulous air sealing, recognizing that poor installation can undermine even the best window products.

Mechanical Systems: From Gas to Efficient Electrification

The building’s mechanical transformation followed the envelope upgrades. Initially, a small, modulating gas boiler provided hydronic heating with low-temperature radiators and radiant floors. By 2016, the system transitioned to ductless cold-climate mini-split heat pumps, sized by updated energy modeling to avoid undersizing (causing discomfort) or oversizing (causing short cycling and poor dehumidification).

Mini-splits were located centrally in each unit to balance temperature distribution, with supplemental fans improving air mixing. The case study found that while temperature differentials remained minor (2-4°F), the key benefit was the mini-splits’ sufficient dehumidification during summer and continued operation during sub-zero winter conditions, albeit with reduced efficiency at extreme lows. Importantly, the mini-splits’ right-sizing allowed for predominant operation in “dry mode” rather than full cooling, maximizing comfort and minimizing energy use.

Despite these advances, the existing gas boiler remained as a backup and for domestic hot water production, due to code limitations and product availability. The ultimate electrification goal includes replacing the boiler with an air-to-water heat pump, further reducing fossil fuel dependency and enabling all-electric operation powered by on-site solar.

Ventilation and Indoor Air Quality: Essential for Healthy, Tight Homes

With high levels of air tightness, mechanical ventilation becomes non-negotiable for occupant health. The project implemented energy recovery ventilators (ERVs) with high efficiency, strategically located to supply fresh air to living spaces and exhaust from bathrooms. The ERVs’ balanced ventilation not only maintained indoor air quality but also minimized energy penalties by recovering both sensible and latent heat.

Special care was taken with duct sealing (using mastic and gasketed connections) and layout, avoiding returns in kitchens to prevent grease buildup in the ERV core. Range hoods were specified with low cfm to prevent depressurization, with code-compliant makeup air solutions considered for higher-capacity exhausts.

Performance Outcomes: Energy Use, Economics, and Comfort

After improvements, annual kilowatt-hour consumption per apartment was approximately half the Illinois average—including most winter heating. The installation of an 8.58 kW photovoltaic array further reduced net energy costs, bringing the building close to net zero in years when heat pumps provided the majority of heating.

Economic analysis revealed the heat pumps outperformed natural gas heating when paired with on-site solar, with annual savings exceeding $200 per apartment. Without solar, the economics fluctuated with utility rates but remained competitive. The payback period for the solar array was projected to reach positive returns within 7-8 years, after which the system would provide decades of ongoing savings.

Comfort improved dramatically, with stable indoor temperatures, controlled humidity, and fresh air—intangible benefits that reinforce the value of high-performance retrofits.

Moisture Management, Durability, and Lessons Learned

Moisture management emerged as a central theme throughout the retrofit. Wall and roof assemblies were designed to maintain bidirectional drying, with materials selected for appropriate vapor permeability. Low-tech monitoring—visual inspection of masonry and joints—proved sufficient, with no evidence of moisture problems over more than a decade of operation. Passive radon mitigation was integrated during basement upgrades as a precaution.

The project’s experience highlighted the importance of contractor selection and supervision. Green building competencies remain rare among contractors; success often depends on close collaboration, oversight, and mutual learning.

User Behavior, Controls, and Occupant Education

No retrofit is complete without addressing occupant behavior. The best technology can be undermined by habits formed in drafty, inefficient buildings. Education for tenants included utility cost transparency, training on ventilation systems, and guidance on optimal thermostat and system use. Building management monitored humidity via smart thermostats, intervening as needed to prevent mold risk.

In multi-unit or rental contexts, the variability of occupant choices can affect net-zero goals and energy performance. The experience suggests that user education, ongoing engagement, and smart controls are essential complements to physical upgrades.

Site and Water Management: Holistic Sustainability

Sustainability extended beyond the building envelope. The project incorporated low-flow fixtures, roughed-in graywater systems (pending code approval), and stormwater strategies such as rain gardens to mitigate combined sewer overflow risks—a significant urban challenge in Chicago. Site interventions were designed for future adaptability and integrated with the building’s resilience goals.

Looking Forward: Future-Proofing and Continuous Improvement

The case study underscores the value of strategic planning and future-proofing. Decisions made in 2009, such as hydronic system design and utility room layout, allowed for later integration of new technologies. Today’s broader array of insulation materials, air sealing products, and smart membranes would offer even more options for performance and durability.

Continuous improvement is part of the sustainable building journey. Plans for further electrification, equipment upgrades, and site enhancements remain underway, reflecting the evolving landscape of building science and technology.

Conclusion

Retrofitting historic masonry housing for energy performance, health, and sustainability is both a technical and human challenge. Success depends on a holistic approach—envelope upgrades, mechanical optimization, ventilation, moisture management, user education, and renewable integration—tailored to each building’s unique context. The lessons from this Chicago project provide a roadmap for housing professionals, builders, contractors, and the general public committed to transforming the existing housing stock into resilient, low-carbon, and livable homes.

For further information and resources, Green Home Institute remains committed to empowering professionals and residents to make informed, sustainable choices in building and renovation.

Key Takeaways

  • Deep energy retrofits of masonry housing can achieve dramatic improvements in energy performance, comfort, and health while preserving embodied carbon and urban infrastructure.
  • Building envelope improvements—insulation, air sealing, high-performance windows—are the foundation of sustainable retrofits and must be tailored to each project’s unique challenges.
  • Moisture management and vapor permeability are critical considerations in all envelope assemblies, especially for historic masonry structures.
  • Mechanical systems, particularly right-sized heat pumps and energy recovery ventilation, are essential for decarbonization and indoor air quality in tight homes.
  • Renewable energy, such as photovoltaics, delivers substantial operating cost savings and supports net-zero goals when paired with envelope and system upgrades.
  • Contractor expertise and hands-on quality control are necessary to ensure proper installation and system performance.
  • Occupant behavior and education significantly influence real-world energy savings and comfort; smart controls and ongoing engagement are vital.
  • Site and water management, including stormwater mitigation and future-proofing for water reuse, contribute to holistic sustainability.
  • Retrofitting is an ongoing process; strategies should prioritize adaptability and incorporate emerging technologies and practices.
  • Strategic planning, data-driven decision-making, and collaboration across disciplines are key to successful, scalable energy retrofits.

Additional Questions and Answers not in the webinar 

Q: Are the Fujitsu heat pumps still working ten years later?
A: Yes, they still work great.


Q: Marcus, would you share the total project cost and whether you received any grants?
A: $180,000 general deep energy retrofit budget, $15,000 back porch rebuild, $17,000 re-roofing, $15,000 cornice and parapet repair, $30,000 solar roof array, $14,000 for three ductless minisplits. Rebates: $1,500 in Energy Star rebates, $1,500 insulation rebate, $1,450 heat pump rebate, 30% Federal tax credit on solar array installation, $9,300 state rebate on solar array installation.

Q: How many attendees were there today? Nice presentation.
A: 200.

Q: How many and what type of water heaters did you use? Could a hybrid water heater be installed in the garden level to reduce humidity?
A: We have one indirect fired water heater for the whole building (120 gallon insulated storage tank).

Q: Do you recommend a smaller, typical air-forced HVAC system with better air sealing/exterior insulation so that the user learning curve is reduced or eliminated?
A: I personally have a deep-seated dislike for forced air systems, and as such it was never on my radar or an option for us. As such, I don’t really have any recommendations I could pass on.

Q: Given everything you’ve learned and experienced, what would you do differently given today’s updated technologies and evolving building science for masonry retrofits like yours (new insulation types, heat pump advances, airsealing products, etc.)?
A: I probably would sequence some of the improvements and tasks differently (more effectively). I would go with a different, more reliable check valve (backwater valve) system from the outset. Rather than applying insulation uniformly across the interior walls, I would increase the insulation in those rooms where I had the space to do so.

Q: Pipe insulation from big box stores has been seen to be short-lived and still externally hot to the touch. Did you use a better grade of pipe insulation?
A: Yes, I used professional grade elastomeric pipe insulation and fittings.

Q: Can you talk a little more about why you incorporated the layer of open cell spray foam? Understood that minimizing the closed cell thickness avoids it becoming a vapor barrier, but open cell spray foam doesn’t really have a much better R value than mineral wool batts. Why not just add more mineral wool instead of open cell?
A: I wanted the potential heating season dew point to be in the spray foam and not the rockwool insulation to minimize condensation and bulk water issues.

Q: Window saddle heat pumps seem to be a coming technology that is much easier and therefore less expensive to install. They are not possible to fit with crank windows at this point. How would you weigh the heat retention advantages of crank windows versus the convenience and expense advantages of saddle heat pumps?
A: I personally would take a systems approach here, and not just look at the potential lower cost of a saddle heat pump. If just looking at cost, a saddle heat pump may be a short-term fix, but not necessarily cost-effective in the long run.

Q: How did you manage the behavioral learning curve with your tenants?
A: It’s an ongoing process. What I noticed is that demonstrating the potential cost savings will more reliably lead to behavior changes—particularly in this economy.
 
*Content created by a human speaker, transcribed by Zoom, and arranged by an AI LLM
 
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Q&A Webinar After

Valuing, Financing High-Performance Green Homes & ADUs Article

Teresa Lopez, Green Energy Money (GEM), joined us recently for our  Weekly Wednesday Free CEU webinar Series.

If you missed this session, want to rewatch it, or want to share it with a friend or colleague, you can now do so, as the recording and an article on the topic are available below. 

What the session was about, according to our live attendees

The webinar highlighted the growing importance of having knowledgeable, specially trained appraisers for valuing green and high-performance homes, emphasizing that many traditional appraisers and realtors still lack understanding of these features. Attendees learned that requesting a green-certified appraiser is possible and critical for proper valuation, with the HERS rating standing out as the leading standard for assessing energy efficiency. The session also covered recent industry progress, such as Fannie Mae’s updated policies, new lending options, and improvements in recognizing green features in appraisals and MLS listings, while noting ongoing challenges like limited appraiser training and the need for better communication about the benefits of sustainable home features.

Please help us keep these webinars and writings going by becoming a supporting GHI member or by making a donation. 

Article Based on Webinar*

Abstract

This article explores the evolving landscape of green home financing, appraisal, and construction, focusing on market trends, valuation practices, and funding strategies for high-performance homes. Drawing exclusively on expert insights presented during the GreenHome Institute’s recent educational session, the discussion addresses challenges and opportunities for builders, contractors, housing professionals, and the general public. Topics covered include the integration of energy efficiency and resilience in new construction and retrofits, the role of appraisals and certifications, emerging financing products, and the knowledge gaps among industry stakeholders. Key takeaways are provided at the conclusion to summarize actionable points for professionals and consumers alike.

Financing and Valuing High-Performance Homes: Bridging the Gaps in Green Building

The residential green building sector continues to advance, driven by a combination of evolving building codes, growing consumer demand for energy-efficient and resilient homes, and a heightened awareness of sustainability in the housing market. Yet, despite significant progress in design strategies, product availability, and technical know-how, one of the most persistent barriers to widespread adoption remains the challenge of financing and accurately valuing high-performance homes. This article examines the current state of green home funding, appraisal practices, and construction trends, as well as the educational and systemic gaps that must be addressed to fully unlock the potential of sustainable housing.

Understanding the Market Gaps: Appraisal, Lending, and Education

A core obstacle facing the green building movement is the disconnect between the technical achievements of high-performance construction and the traditional mechanisms for property valuation and financing. Historically, appraisals have struggled to appropriately recognize the added value of energy efficiency, resilience, and other sustainable features. The market’s reliance on comparable sales (comps) often leaves out the data needed to establish the so-called “green premium”—the additional value associated with advanced building practices.

Recent updates are helping to close this gap. Notably, Fannie Mae’s adoption of the Uniform Appraisal Dataset (UAD) 3.6, which now incorporates Home Energy Rating System (HERS) scores and other performance measures, is a significant step toward more accurate valuation of green homes. Still, the standard reporting criteria on a national scale remain limited, and custom-built high-performance homes frequently do not appear in Multiple Listing Services (MLS), further hampering data collection.

The educational gap is equally critical. Builders, appraisers, underwriters, and real estate professionals often lack the training to identify, document, and value green features. While consumers—especially those in IT and engineering fields—are increasingly educated about these aspects, industry professionals must continue to bridge the knowledge divide to ensure that high-performance homes are properly valued and financed.

The Role of Building Codes and Certification

Building codes have become a major driver of change in the residential sector. In many regions, adherence to the 2024 code effectively positions builders as “green builders” by default, with HERS scores near 60 now aligning closely with code-built homes. High-performance homes that go further—such as those certified to Passive House standards or achieving HERS scores below 40—set new benchmarks for energy efficiency and resilience.

Third-party certifications play an essential role in supporting appraisals and financing. The HERS rating, in particular, is widely recognized for its ability to provide both predictive and verified energy savings. Other certifications, including ENERGY STAR, LEED, and the Department of Energy’s Home Energy Score for existing homes, also contribute to the valuation process. However, the ability of these certifications to influence appraisals depends on the appraiser’s training and the availability of supporting data.

Trends in High-Performance Housing: ADUs, Retrofits, and Resilience

Current market trends reflect both innovation and adaptation in response to changing consumer needs and policy environments. Accessory Dwelling Units (ADUs) have emerged as a powerful tool for increasing housing density, affordability, and multi-generational living. In states like California and Texas, relaxed zoning and building codes have enabled the proliferation of ADUs and small pocket communities, fostering both flexibility and attainability in the housing market.

The retrofit market represents a massive, untapped opportunity, with over half of America’s homes now more than fifty years old. Deferred maintenance is a pervasive issue, and the average energy-efficiency upgrade costs approximately $50,000. Regular maintenance and timely upgrades are essential not only for ongoing savings but also for preserving and enhancing property value.

Resilience is increasingly at the forefront of design and construction, with homeowners and builders prioritizing climate risk mitigation and durability. Integrated systems such as solar power, battery storage, and electric vehicle charging are becoming standard features in high-performance homes, offering operational cost savings and improved comfort.

Financing Mechanisms: Rebates, Mortgages, and Innovative Products

The complexity of green home financing arises from the need to balance higher upfront costs with long-term savings and value. Funding sources for high-performance projects are diverse, ranging from federal and state rebates—such as those provided under the Inflation Reduction Act—to utility incentive programs and specialized loans.

One of the most robust strategies for financing green projects is to leverage the mortgage process itself. By integrating the cost of energy-efficient improvements into the primary mortgage, buyers can take advantage of long-term, low-interest financing while simultaneously increasing the home’s value and reducing operational costs. New loan products, such as second-lien construction loans for ADUs and structured buy-downs (e.g., 3-2-1 programs), provide additional flexibility and make it easier for homeowners to invest in upgrades without sacrificing favorable rates on existing mortgages.

Reverse mortgages are another avenue for seniors with substantial home equity, enabling them to fund improvements or add ADUs for passive income without taking on new monthly payments. These options are particularly relevant as property tax and insurance costs continue to rise for older homeowners.

For builders and investors, recent guideline changes from Fannie Mae now allow up to five or six residential units under the same favorable terms as single-family homes, keeping projects out of the commercial lending sphere and making high-performance multifamily construction more attractive.

Appraisal Practices: The Importance of Data and Competency

Valuing green homes requires a nuanced approach that recognizes both tangible and intangible benefits. The UAD 3.6 mandates that appraisers identify specific green features and utilize mandatory certification reporting. However, the continued reliance on the sales comparison approach underscores the need for robust data collection and skilled interpretation.

The present value formula for energy savings enables appraisers to justify up to a 15% line-item adjustment for energy efficiency, but they must have access to accurate and relevant data. The appraiser’s competency is critical; homeowners and builders are entitled to request appraisers who are specifically trained to value green homes. Despite this, many lenders and appraisal management companies have yet to develop green appraisal panels or prioritize this expertise in their processes.

To address missing data in comps, appraisers can use the year built and corresponding building code as proxies for performance, connecting them to HERS or other rating systems. This approach helps quantify the difference between standard and high-performance homes even in the absence of direct sales comparisons.

Bridging the Educational Divide: Realtors, Appraisers, and Documentation

A significant knowledge gap persists in the resale market, where the high-performance features of a home are often lost or inadequately documented in real estate listings. Real estate professionals play a crucial role in ensuring that green attributes are communicated clearly and prominently, rather than buried in listing comments. Using precise language—such as “high performance” instead of “green”—can help distinguish homes that exceed current code and maximize their market value.

Data retention is equally important. Homeowners and builders should maintain comprehensive records of certifications, ratings, and upgrades, ensuring that the information is available at the time of resale or refinancing. Tools like Pearl Certification and municipal energy score programs (e.g., Portland’s mandatory Home Energy Score) are helping to standardize and disseminate this information, making it easier for appraisers and buyers to assess value.

Challenges and Opportunities in the Path Forward

Despite substantial progress, the green building sector remains a niche within the broader housing market. The absence of standardized, nationally recognized energy performance metrics complicates training and adaptation among appraisers and lenders. As building codes become more stringent and market expectations evolve, it is anticipated that the distinction between code-built and high-performance homes will diminish over the next decade.

Training and education remain top priorities. Appraisal panels must expand their expertise, and builders, contractors, and real estate professionals need ongoing support to stay current with advances in green building and valuation. The increasing adoption of standardized tools and certifications will further facilitate accurate valuation and financing.

Conclusion

The transition to high-performance, green homes offers immense benefits in terms of operational costs, comfort, resilience, and long-term value. However, realizing these benefits hinges on the ability of the housing industry to align financing, appraisal, and educational practices with the realities of modern construction and market demand. By embracing integrated funding strategies, leveraging certifications, and prioritizing data transparency and professional training, the industry can bridge the remaining gaps and ensure that sustainable housing reaches its full potential for all stakeholders.

Key Takeaways

  • Accurate valuation of green homes depends on robust data, third-party certification, and appraiser competency.
  • Building codes are increasingly aligning with green building standards, making high performance the new normal in many regions.
  • Financing tools—from rebates and incentives to innovative mortgage products—are evolving to support high-performance construction and retrofits.
  • The retrofit market represents a significant opportunity for energy savings and property value enhancement, especially in older homes.
  • Resilience, multi-generational living, and integrated technologies (such as ADUs and solar) are shaping the future of residential design.
  • Comprehensive documentation and clear communication by real estate professionals are critical for maintaining the value of high-performance features during resale.
  • Ongoing education and training for builders, appraisers, and lenders are essential to closing knowledge gaps and ensuring widespread adoption of sustainable building practices.
*Content created by a human speaker, transcribed by Zoom, and arranged by an AI LLM
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Duct Diagnostics: Evaluation & Troubleshooting for Real-World Systems

Brynn Cooksey Sr., the Air Doctr, joined us recently for our  Weekly Wednesday Free CEU webinar Series.

If you missed this session, want to rewatch it, or want to share it with a friend or colleague, you can now do so, as the recording, an extra Q&A follow-up, and an article on the topic are available below. 

What the session was about, according to our live attendees

The webinar provided attendees with valuable insights into diagnosing and optimizing ducted HVAC systems, emphasizing the importance of understanding static pressure, airflow, and duct leakage. Participants learned about a variety of diagnostic tests and tools—such as pressure pans, duct blasters, and manometers—for identifying issues that affect system performance, comfort, and energy efficiency. Key takeaways included the need for proper duct sealing and sizing, the limitations of common materials like duct tape, and the significant impact of pressure imbalances and leaks. Both newcomers and seasoned professionals gained practical tips and a greater appreciation for thorough, methodical testing and maintenance of ductwork to ensure optimal system operation.

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Article Based on Webinar*

Abstract

Effective ductwork is at the heart of energy-efficient, healthy, and comfortable homes. As the residential sector increasingly adopts advanced HVAC systems—particularly air source heat pumps—duct system performance has become even more critical for both new and existing homes. This article synthesizes expert insights and field experience on duct diagnostics, evaluation, and practical improvements. The focus is to empower housing professionals, builders, and contractors to understand, assess, and optimize duct systems for better comfort, durability, and sustainability. Drawing exclusively on material from a GreenHome Institute educational session, this white paper covers core concepts, diagnostic methods, common problems, and actionable solutions for robust duct design and troubleshooting.

Introduction

The duct systems installed in residential buildings are fundamental to the success or failure of heating, cooling, and ventilation strategies. From single-family homes to multifamily dwellings, the quality of ductwork directly impacts energy consumption, indoor air quality, comfort, and the longevity of mechanical equipment. As heat pump technology and decarbonization efforts accelerate, scrutiny of duct systems—many of which were poorly designed, undersized, or inadequately sealed—has never been more urgent. Even in new construction, suboptimal ductwork remains a persistent problem, often resulting in discomfort, inefficiency, and system failures.

This article will explore the technical principles of duct system evaluation, highlight best practices for diagnostics and balancing, and offer solutions for common issues encountered in the field. While the content is aimed at housing professionals, the technical material is presented in an accessible manner for a broad audience, including contractors, builders, and interested homeowners.

The Role and Purpose of Duct Systems

A properly designed duct system delivers conditioned air efficiently and evenly throughout every room in a home. According to established standards, a well-designed system should keep room temperature variations within three degrees Fahrenheit. This evenness is essential for occupant comfort and energy efficiency.

Ducts must not only be sized appropriately but also be tightly sealed and balanced for both supply and return air. Any deficiencies in these areas can lead to a cascade of issues: uneven temperatures, noisy operation, excessive energy consumption, and even safety hazards such as heat exchanger failures and indoor air quality problems.

Sizing and Balancing: The Foundation of Performance

Field surveys of nearly 4,000 homes—ranging from early 1900s houses to those completed as recently as 2020—have revealed a staggering reality: nearly 99% of duct systems are undersized, often operating at half the required capacity. This is not merely a legacy problem. Many new homes, despite using advanced heating and cooling equipment, are delivered with duct systems that fail to meet even the minimum design criteria.

Proper sizing starts with accurate load calculations (Manual J) and duct design procedures (Manual D). The goal is to ensure every room receives the calculated cubic feet per minute (CFM) of air needed for both heating and cooling loads. When the system is not balanced—meaning the supply and return airflows do not match—comfort, efficiency, and equipment reliability all suffer.

Balancing is a commissioning process involving the measurement and adjustment of airflow at each register, typically using devices such as a flow hood. Balancing dampers—metal blades installed inside ducts—allow fine-tuning of airflow to different branches, compensating for differences in heating and cooling requirements. However, balancing is rarely performed in residential construction, often resulting in persistent comfort complaints and inefficient operation.

Duct Sealing and Insulation: Controlling Energy Loss

Duct leakage is a major source of energy waste in both old and new homes. Studies indicate that unsealed ductwork can lose 20% to 40% of conditioned air, with an average of about 30%. Sealing is essential but must be preceded by proper sizing—sealing undersized ducts can worsen static pressure and damage equipment.

Ducts running through unconditioned spaces (such as vented attics or crawl spaces) require both sealing and insulation. Uninsulated ducts in these locations lead to heat loss or gain, reducing system capacity and increasing heating or cooling loads. Inside the thermal boundary of the home, insulation is less critical but may still improve comfort.

System Controls and Advanced Solutions

Modern thermostats have evolved into sophisticated building controls, offering features like geofencing and remote access. These advancements enable more precise temperature management and can help optimize system performance. Additionally, zoning—using motorized dampers and multiple thermostats—can address persistent comfort issues in multi-story or large homes, yielding up to 10% energy savings when implemented with proper duct sizing.

Consequences of Poor Duct Design and Installation

Inadequate duct systems manifest in a variety of problems:

  • Hot or cold spots in rooms, making them uncomfortable or unusable
  • Longer running times for HVAC equipment, driving up utility bills
  • Equipment short cycling, leading to premature failure of components such as compressors or heat exchangers
  • Safety hazards, including cracked heat exchangers (which can release combustion gases into living spaces)
  • Excessive system noise, which can degrade quality of life
  • Indoor air quality concerns, especially when return leaks pull in attic or crawl space air containing dust, mold, or other contaminants

Diagnostic Methods: Evaluating Duct System Performance

Thorough evaluation of duct systems requires a systematic approach, combining client interviews, physical inspection, and a suite of diagnostic tests. Key techniques include:

  1. Pressure Pan Test: Measures pressure differences at registers with a blower door running. Detects leaks connecting the duct system to outside the building shell.
  2. Duct Leakage Test (Duct Blaster): Quantifies total duct leakage by pressurizing or depressurizing the duct system to 25 pascals and measuring airflow loss. Leakage should not exceed 10% of total system airflow.
  3. Room-to-Room Pressure Differential: Assesses pressure imbalances between rooms with doors closed, using a manometer. Imbalances greater than 3 pascals indicate inadequate supply or return paths, leading to comfort and efficiency problems.
  4. Direct Airflow Measurement: Using flow hoods or vane anemometers, technicians measure delivered CFM at each supply and return register, comparing actual values to design targets.
  5. Static Pressure Measurement: External static pressure readings (before and after filters and coils) provide a proxy for airflow. High static pressure indicates restrictions—often due to undersized ducts, dirty filters, or excessive bends.
  6. Temperature Rise Test: For combustion appliances, measuring the temperature difference across the heat exchanger can indicate insufficient airflow if the rise exceeds manufacturer specifications.
  7. Duct Traverse and Other Tools: Advanced tools such as flow plates and duct traverses (using multiple velocity measurements) offer high accuracy for airflow quantification, though they may be more time-consuming.

Common Problems and Practical Solutions

  • Duct Leakage: The most energy- and comfort-robbing issue. Sealing with mastic or approved sealants (not “duct tape”) is essential. Prioritize ducts outside the thermal envelope for sealing and insulation.
  • Undersized Ducts: If airflow measurements fall below calculated needs and static pressure is high, ducts may need to be enlarged or additional supplies/returns added.
  • Imbalanced Airflow: Use balancing dampers, jumper ducts, transfer grilles, or dedicated returns to address pressure differentials between rooms.
  • Noise: Excessive noise typically results from high static pressure or poor duct design. Reducing restrictions and increasing duct size are effective remedies.
  • Filter Upgrades: High MERV filters improve air quality but can increase static pressure. Always verify that the system can accommodate higher resistance filters before upgrading.
  • Return Path Limitations: Inadequate return air is a common culprit for pressure imbalances. Solutions include undercutting doors (with some loss of privacy), installing jumper ducts or transfer grilles, or adding dedicated returns.
  • Zoning Adjustments: For large or multi-story homes, zoning with motorized dampers and multiple thermostats can correct persistent comfort problems and save energy.

Assessment and Remediation Process

A comprehensive evaluation should begin with a client interview to identify comfort complaints, noise issues, or specific rooms that are problematic. This is followed by a physical inspection for visible flaws—such as disconnected ducts, improper modifications (e.g., “Bluetooth ducting” where other trades have compromised the ductwork), or signs of leakage.

The six major diagnostic tests outlined above provide quantitative data to confirm or refute suspected issues. Once identified, solutions can be targeted—from simple sealing and balancing to more involved duct modifications or equipment replacement.

Special Considerations for Existing and New Homes

Older homes often present hidden challenges—ducts buried in wall cavities, pan joists serving as return pathways, or inaccessible duct runs. While it may not always be feasible to replace or enlarge ducts without major renovations, targeted improvements (such as adding returns, sealing accessible joints, or employing advanced diagnostics like borescopes) can still yield significant benefits.

For new construction, engaging duct design professionals early in the process is essential. This ensures that load calculations, duct sizing, and layout are coordinated with architectural and structural plans. Duct leakage and performance testing should be included at mid-construction to enable corrections before finishes are installed.

The Cost of Inaction

While professional duct evaluation and remediation entail upfront costs, the price of neglect is far higher: persistent comfort issues, inflated utility bills, compromised indoor air quality, and premature equipment failure. Investing in proper design, testing, and commissioning pays dividends over the life of the home.

Key Takeaways

  • Duct systems play a critical role in home energy efficiency, comfort, and indoor air quality.
  • A vast majority of residential duct systems—both old and new—are undersized and/or poorly sealed.
  • Proper duct system performance requires accurate load calculations, professional design, and thorough commissioning.
  • Diagnostic tests such as pressure pan, duct leakage, static pressure, and direct airflow measurements are essential tools for identifying and solving duct problems.
  • Sealing ducts is important but must follow correct sizing; insulation is crucial for ducts outside the building’s conditioned envelope.
  • Balancing airflow with dampers and considering zoning can solve persistent comfort issues, especially in larger or multi-story homes.
  • System noise, pressure imbalances, and temperature variations are often symptoms of underlying duct design or installation faults.
  • High-performance filters should be matched with duct system capacity to avoid excessive static pressure.
  • Early involvement of qualified professionals in both new construction and retrofit projects is key to achieving high-performance duct systems.
Addtional Q&A Answers

Q: On the general static pressure and fan speed chart, was that a real chart? It looked like the equipment would have to have been rated at 0.3 IWC? So if it’s even 0.5 IWC it would be too much pressure?
A: This was an example to demonstrate how to use the chart for Total External Static Pressure (TESP). The chart was not specific to a particular piece of equipment but rather intended as a general reference.

Q: Brett, will this duct handout be shared via link in Zoom chat or emailed to us separately?
A: We are having issues with the handout at the moment. Please stay tuned for updates.

Q: How about internal video inspection?
A: (Answered live) We take a sample of the duct system to inspect for cleanliness.

Q: This info is very technical for an architect to explain to a client who has problems with an existing or new system that would need to check duct-leaks & balance a 2-season system. If I am to recommend a verification process, what would be the cost a client would need to pay for a 2,000 SF 2-storey with basement house that covers both seasons? (This would be the starting point)
A: Hi Rosmal, the cost depends on several factors. Proper duct leakage testing requires knowing the square footage served by each system. For duct balancing, it’s recommended to have mechanical plans and manufacturer specs to compare with the original HVAC design. The total cost will likely exceed $1,000.

Q: Without removing walls and rebuilding ductwork from scratch, how do you go about balancing and getting cool air to the second floor? It’s at least 10 degrees warmer or colder upstairs.
A: Sarah, I recommend starting with duct leakage testing to ensure the ducts aren’t excessively leaky. Poorly installed insulation can also contribute to large comfort issues, which I often see as an energy auditor. Zoning is the only true way to resolve a hot second floor, as the thermostat will satisfy the first floor long before the second floor is cooled.

Q: How is a pan between joists replaced? Is it simply by installing a complete rectangular duct between joists?
A: (Answered live) Replace the pan joist return air with rectangular or round ductwork as much as possible. Note that static pressure may still be high due to the tightness of wall cavities.

Q: If replacing ducts at time of renovation, exposed ducts vs. boxed in? Is exposed ducting (not insulated) in living space an advantage due to more radiation surface in addition to conditioning via air flow?
A: (Answered live) The radiant heat is lost to the inside of the building shell. There is generally no benefit to boxing in ducts, and it is not cost effective.

Q: I was referring to ducts inside the living space, not external to living space.
A: The duct loss isn’t always where you want it; it may help if the loss is to the room being conditioned, but not if it goes elsewhere. This is another reason why minisplits or window units are often a good solution.

Q: Drew, as a Rater I think mini splits are awesome, especially ductless ones. However, installing them on large custom homes—which is a bulk of our new builds out here—is not very doable and would require a lot of outdoor units.
A: That’s correct. While ductless mini splits are excellent for certain applications, large custom homes may face practical limitations with the required number of outdoor units.

Please help us keep these webinars and writings going by becoming a supporting GHI member or by making a donation. 

*Content created by a human speaker, transcribed by Zoom, and arranged by an AI LLM
Categories
Q&A Webinar After

Tour the MiNet0-1, triple-certified home with low embodied carbon Article & Q&A

Dale Hulst joined us recently for our  Weekly Wednesday Free CEU webinar Series.

If you missed this session, want to rewatch it, or want to share it with a friend or colleague, you can now do so, as the recording, an extra Q&A follow-up, and an article on the topic are available below. 

In addition to the webinar recording, you can virtually visit the home via this Matterport walkthrough to get a sense of the space and its features, and you can download the certification checklists, energy rating technical documents, appraisal addendum, and solar value here.

What the session was about, according to our live attendees

During the webinar, attendees learned about the significant attention to detail and coordination required to build truly sustainable, high-performance homes, such as those aiming for Passive House (PHIUS), Net Zero, or LEED certifications. Presenters emphasized that achieving these standards often involves innovative approaches to foundations—such as wood-based or concrete- and foam-free options—advanced air sealing, and meticulous design to ensure efficient air flow and circulation. The importance of early and thorough collaboration with raters and contractors was highlighted to avoid costly rework and ensure compliance. The session also covered how building orientation, window selection (including quadruple-pane and variable SHGC windows), and all-electric systems powered by on-site solar contribute to net-zero operational energy and low embodied carbon. Attendees reported learning about several new technologies and construction methods, such as quadruple-pane krypton windows, remote compressor water heaters, and the use of recycled glass material (Glavel) as an insulation or structural base. Many were exposed for the first time to the concept of slabless or wood foundations, climate adhesive products, and the need to manage air stratification in tightly sealed, energy-efficient homes. The webinar also showcased innovative products like wood fiber insulation, super stretchy sealants, and best practices for fresh air intake and HVAC design. Overall, participants appreciated the practical insights, product information, and real-world lessons shared, particularly from the detailed virtual home tour and the experiences of the project team.Please note this project is for sale, and you can learn more about that here if you are interested in living net positive in West MI.

This home is for sale, so learn more here if you want to live Net Positive in West MI!

Article Based on Webinar*

This article provides a comprehensive exploration of the MI Net01 Triple Certified Home with Low Embodied Carbon in Grand Rapids, Michigan. The project demonstrates the integration of Passive House principles, advanced energy and water efficiency, reduced embodied carbon, durability, and resilient design. It also highlights key technical strategies and lessons learned, offering practical guidance for housing professionals, builders, contractors, and an interested general audience. The discussion focuses on how high-performance homes can be designed and constructed to meet evolving sustainability goals, while balancing technical rigor with real-world constraints.

Introduction

The journey toward truly sustainable housing is marked by innovation, collaboration, and a commitment to measurable outcomes. The MI Net01 Triple Certified Home in Grand Rapids, Michigan, stands as a model of such progress. Triple certified under Passive House US (PHIUS), ENERGY STAR, and the Green Star Homes Platinum level, and submitted for LEED Platinum, this residence exemplifies the next generation of high-performance, low-carbon homes. Its development offers actionable insights for housing professionals, builders, contractors, and anyone interested in the future of sustainable living.

Project Overview and Certification Pathways

At the heart of the project’s success is an integrated approach to certification. The home achieves PHIUS Source Zero certification, which requires rigorous energy modeling, construction quality assurance, and operational efficiency. By pursuing PHIUS, the project automatically engaged with ENERGY STAR and Zero Energy Ready Home requirements, ensuring a robust baseline of building performance. The home’s HERS Index rating of -28, compared to typical code-built homes scoring 55–65, sharply illustrates its dramatically reduced energy demand and net positive energy production.

The Green Star Homes Platinum certification further recognizes the home’s achievements in energy, water, health, resilience, and electrification. The pursuit of LEED Platinum underscores the comprehensive nature of the project, with third-party verification at every stage.

Design Goals and Philosophy

The project was guided by four primary objectives:

  1. Achieve net-zero operational energy, including the capacity to power two electric vehicles daily.
  2. Significantly reduce embodied carbon through thoughtful material selection and innovative construction techniques.
  3. Create a home that is “lagom”—not too little, not too much, but just right—emphasizing comfort, durability, and ecological landscaping.
  4. Ensure resilience against climate risks, including wind, heat, cold, and moisture, while prioritizing occupant health and long-term durability.

Net-Zero Operational Energy

Achieving net-zero energy performance required a holistic systems approach. The home’s solar photovoltaic array is sized not just for household electricity, but also for two electric vehicles, each driving an estimated 33 miles per day. The roof pitch was optimized (12:12) for maximum winter solar gain, supporting heating loads at times of peak demand.

Passive solar design was carefully employed, with south-facing windows protected by overhangs and porches to manage seasonal solar gain. The building envelope was engineered to minimize heat loss, with a focus on airtightness, high-performance insulation, and advanced window technology. These measures not only reduce energy use, but also contribute to exceptional occupant comfort and quietness.

Embodied Carbon Reduction

A notable aspect of the project is its commitment to reducing embodied carbon—the greenhouse gas emissions associated with materials and construction. The home avoids high-carbon materials such as foam insulation and concrete wherever possible. Instead, it features a pioneering concrete-free, foam-free foundation using wood footings and foam glass aggregate made from recycled glass. This system provides both insulation and drainage, and demonstrates a replicable, code-compliant alternative to conventional slabs.

Above grade, the building envelope employs Timber HP wood-fiber insulation, which not only reduces embodied carbon but also sequesters carbon within the building assembly. The use of durable, low-maintenance siding and roofing further minimizes the structure’s long-term carbon footprint.

Overall, the embodied carbon calculation for the home’s envelope shows a reduction of nearly 60% compared to a conventional build, translating to savings of approximately 35 metric tons of CO2 equivalent.

Durability, Resilience, and Health

The home is designed to withstand climate extremes, including heavy winds, extreme temperatures, and potential flooding. Premium materials, such as a standing seam metal roof with a 60-year life expectancy, and robust water management strategies, contribute to longevity.

A climate-resilient adhesive was used throughout the structure to enhance wind resistance and structural integrity. The double-wall assembly, detailed air and vapor barriers, and continuous insulation create a building envelope that maintains comfort without mechanical systems for extended periods, even during power outages.

The project’s approach to indoor air quality is equally rigorous. A dedicated energy recovery ventilation (ERV) system supplies continuous fresh air, with filtration capable of removing wildfire smoke and volatile organic compounds (VOCs). All construction materials were selected for low emissions, and air quality monitoring is built into the home’s operations.

Water Efficiency and Management

Water conservation was addressed through efficient fixtures, native landscaping (including a rain garden), and advanced filtration. The home achieved an 8 out of 10 on the Green Star water score, reflecting both conservation and quality. A heat pump water heater with CO2 refrigerant (Sanco) was installed for domestic hot water, further reducing energy use and environmental impact.

Construction Innovations and Lessons Learned

Foundation and Envelope

The concrete-free, foam-free foundation is a standout feature, utilizing a shallow frost-protected assembly with foam glass aggregate, Stego vapor barrier, and wood footings. This system, while innovative, required careful coordination with local inspectors and iterative design development. The walls employ a double-stud assembly, with dense-packed wood-fiber insulation and intelligent vapor control membranes (Intello) that respond dynamically to humidity conditions.

Windows and Glazing

High-performance quad-pane, tilt-turn windows were specified to meet the exacting winter heating demand modeled for the project. Window placement and solar heat gain coefficients were optimized for seasonal performance, with attention to minimizing thermal bridging and maximizing airtightness. The windows are mounted using specialized over-insulation techniques to further reduce energy losses.

Ventilation and HVAC

A single mini-split heat pump provides space heating and cooling, supported by the ERV for distribution. However, the project revealed that relying solely on the ERV for heat distribution can result in temperature stratification. To address this, a supplemental air mixing system with quiet, efficient plenum fans was installed, ensuring even temperatures throughout the home. This lesson emphasizes the importance of active air circulation in super-insulated, airtight homes.

Monitoring and Controls

The home is extensively monitored, with real-time energy, water, and air quality data accessible to both the builder and future occupants. Battery storage, EV charging, and solar production are integrated, providing grid resilience and empowering occupants to manage their resource use.

Certification and Quality Assurance

Third-party verification was integral to the project’s success. Each certification—PHIUS, ENERGY STAR, Green Star, and LEED—involved detailed design review, mid-construction inspections, and final performance testing. The home achieved exceptional blower door test results, with air leakage rates well below even the stringent Passive House requirements. Verification extended to insulation density, mechanical system balancing, and documentation of all material and installation details.

Cost, Scalability, and Market Realities

While the home demonstrates what is technically possible, it also highlights the challenges of cost and scalability. Premium materials, advanced assemblies, and extensive verification can increase upfront costs beyond typical market expectations, particularly for first-time high-performance projects. Site-specific factors, such as lot topography and local labor markets, further influence final costs.

The project team acknowledges that future iterations can achieve similar or improved performance at lower cost through design simplification, more standard lot selection, and value engineering. As verification and embodied carbon accounting become more streamlined and integrated into mainstream practices, these techniques can become increasingly accessible to a broader segment of the housing industry.

Practical Guidance for Builders and Professionals

For those seeking to replicate or adapt these strategies, several key recommendations emerge:

  • Engage all certification and verification partners early in the design process to identify and resolve potential issues before construction.
  • Prioritize integrated design, where architects, engineers, builders, and verifiers collaborate from concept through completion.
  • Invest in quality control, especially regarding air sealing, insulation installation, and moisture management.
  • Consider innovative foundation and envelope assemblies as alternatives to conventional, high-carbon systems—while maintaining code compliance and local inspector engagement.
  • Specify high-performance windows and pay careful attention to their installation details to minimize thermal bridging and air leakage.
  • Plan for active air mixing or distribution, particularly in homes with a single-point heat pump and high levels of insulation/airtightness.
  • Use real-time monitoring to validate performance and inform future projects.

Conclusion

The MI Net01 Triple Certified Home presents a compelling case for the future of sustainable housing. Through a relentless focus on performance, verification, and continuous improvement, the project team has created a home that sets new benchmarks for energy, carbon, durability, and occupant health. While some aspects represent the leading edge of current practice, many strategies are immediately transferable to new builds and retrofits alike.

The project demonstrates that ambitious sustainability goals are achievable with careful planning, collaboration, and a willingness to innovate. As embodied carbon accounting, electrification, and resilience become mainstream, the lessons from this project will inform the next generation of high-performance buildings.

Key Takeaways

  • Integrating multiple certifications (PHIUS, ENERGY STAR, Green Star, LEED) ensures comprehensive performance and quality assurance.
  • Passive House principles deliver exceptional energy efficiency, comfort, and resilience, but require meticulous design and construction.
  • Innovative concrete-free, foam-free foundation systems can dramatically reduce embodied carbon while maintaining performance and code compliance.
  • Material selection, particularly wood-fiber insulation and durable cladding/roofing, is critical to long-term carbon and maintenance outcomes.
  • High-performance windows and airtight construction are essential for minimizing energy use and maximizing occupant comfort.
  • Active air mixing or distribution is necessary in super-insulated homes to prevent temperature stratification.
  • Real-time monitoring of energy, water, and air quality supports ongoing performance validation and occupant health.
  • Early and integrated collaboration among architects, builders, contractors, and verifiers is essential to project success.
  • While premium performance can increase costs, many techniques are scalable and will become more affordable as the market evolves.
  • Embodied carbon accounting is an emerging field; streamlined tools and integration with energy modeling will support broader adoption.

Here’s a detailed Q&A write-up based on the provided questions and the speaker’s answers:

Yes, PV array was sized to power the house and two EVs at 33 mile/day each, assuming 3 miles/kWh which is the USA average. This adds up to just over 4 MWH/EV/year.So roughly speaking, the PV array is sized to provide 8 MWh/year for the EVs and 7 MWh/year for the house. It takes a lot of power to move vehicles down the road!

Note that the PV array is 32 panels totaling 12.48 kWp. On the 12/12 south- facing roof, with modest shading, it is modeled to produce just over 15 MWh/year.Also note that the utilities in Michigan allow for 4.25 MWh/EV charger/year for new construction array sizing and interconnection approval.

Costs sunk into the house including the lot, architectural fees, certification fees, materials, subcontractors, employee labor, Dale’s direct labor, and the cost of money total ~$1619K. Credits including material and utility rebates and the Federal Investment Tax Credit totaled ~$56K. Therefore net costs total ~$1563K. A 7% project markup puts the asking price at ~$1678K.

The metal roof was custom roll-formed to length on site by https://buistsheetmetal.com/ using 17” 24ga panels from Drexel 

Interesting that Alpen is no longer shipping the windows with pressure-equalizing bags, but is instead charging them with the right amount of gas for the final location.

This will save site labor, thank you.For more details on the concrete-free and foam-free foundation and envelope, see these two JLC articles: https://www.jlconline.com/author/dale-hulst/

For more information on Climate Adhesive: https://climateadhesive.com/

I was aware that Holcim Cement was working on eco mixes but could not get contractors or redi-mix places in town to send me data. It seems it might be available now per this AI search? If so, that is good! I will chase again next time. (If there is a gap between what is possible and what is practical for one residential project, perhaps a group of eco-committed contractors could work with a local redi-mix plant to offer eco- mixes, say, one day a week?)The final blower door pressurization/depressurization average was 157 CFM = 0.0282 CFM50/ft2 which is less than half of the Phius requirement of 0.06 CFM50ft2 of envelope. This converts to ~0.60 ACH50.

Windows used were Alpen Tyrol quad pane (thinglass for the inside two panes). I see the frames have been redesigned a bit since I bought the ones at the house. Here’s alink to the current version: https://www.thinkalpen.com/tyrol-residential-upvc-windows

Low carbon materials were difficult to find. I would always ask for low carbon products (net zero if possible) that were also healthy (red list free). If there were some options I would also ask for EPDs. It is a time-consuming process that involves trying to get good data and not just good marketing. I’m proud of many of the materials we chose…and still had some that are imperfect. You can see many of the materials chosen in the Matterport virtual 3D tour on the pins.

About appraisals, my understanding is that the bank will have one done when a potential buyer goes to them for a loan. Their appraiser may know very little about high performance/green construction and therefore undervalue the house. Therefore I was considering hiring someone with experience appraising high performance houses with solar so I would have my own independent assessment. They would use a document called the “green addendum” which lists all the energy saving features and certifications.

I filled one out just to see how it worked; see attached.

Batteries are Enphase 5P which are lithium iron phosphate = safer chemistry than lithium NMC. https://enphase.com/store/storage/gen3/iq-battery-5p

Details on the windows:Header Details Jamb detail:Sill detail

Keep checking back because we are updating this article with new findings on this home, for example

Dale noticed PM2.5 levels jumping up sometimes (without VOCs going up…which is typical for cooking).

The PM2.5 level would drop with increased ERV ventilation, so it wasn’t due to dirty incoming outside air.
(The MERV16 final filter on the ERV is doing its job!)
After testing and disproving one theory (oil residue on ducting), Dale notice that the PM2.5 would increase whenever he would refill and restart the ultrasonic humidifier.
The humidifier had been run to maintain humidity above 35% through the winter and dry spring days to avoid damage to woodwork.
The humidifier was filled with RO water produced by a WaterDrop G3P600 undersink Reverse Osmosis filter.  The Total Dissolved Solids (TDS) number of 8 PPM, which Dale had figuring was clean enough to not produce any white dust.
While no white dust is visible anywhere, it is clear that the Airthings monitor is sensitive enough to pick up the mineral particles in the air (likely calcium left in the RO water).
Here’s an AI search with good information.
I’m quite sure that there was some mineral dust in the air and not fine water particles because the Airthings monitor was at least 10’ from the humidifier, the airflow patterns were not carrying the mist in the direction of the monitor, and the mist appeared to be completely evaporated within about 4’ of the humidifier.
Conclusion: stay away from ultrasonic humidifiers unless you’re using pure (0 PPM) distilled or RO water. 
*Content created by a human speaker, transcribed by Zoom, and arranged by an AI LLM
Categories
Q&A Webinar After

Reducing Wind Impact Risk and Costs in Homes

Alexandra Cary joined us recently for our  Weekly Wednesday Free CEU webinar Series.

If you missed this session, want to rewatch it, or share it with a friend or colleague, you can now do so, as the recording, extra Q&A follow-up, and article on the topic are available below. 

What the session was about, according to our live attendees

Webinar attendees learned that homes can be significantly strengthened against wind and storm damage by following specific construction best practices and standards such as those outlined in the FORTIFIED program. Many participants were surprised to discover the importance of using certified contractors, ring shank nails with close spacing, sealing roof sheathing joints, and incorporating details like drip edges to protect against water intrusion. There was also a strong emphasis on the critical role of garage doors in storm resilience—if a garage door fails during a hurricane, it can lead to catastrophic structural damage. Attendees found it valuable to learn how relatively simple upgrades, such as using rated doors and proper fastening systems, can make a home much more resistant to severe weather.

Article Based on Webinar*

Abstract

Climate-related risks to housing have become increasingly significant, demanding a proactive, systems-based approach to resilient home design, renovation, and construction. This article synthesizes the research and strategies developed by the Insurance Institute for Business and Home Safety (IBHS) through its Fortified program, as presented by Alexandra Cary, Fortified Market Development Director. It explores the science and practical applications behind reducing risk, impact, and insurance costs for homes exposed to wind, hail, hurricanes, and other natural hazards. The article is written for housing professionals, builders, contractors, and the interested public, offering in-depth, actionable knowledge for building stronger, safer, and more sustainable homes.


Introduction

The intersection of climate change, the increasing frequency of catastrophic weather events, and the vulnerability of the housing stock presents a challenge—and an opportunity—to the building industry. Over the last several years, natural disasters have inflicted hundreds of billions of dollars in damage to homes and communities across the United States. The Fortified program, developed by the Insurance Institute for Business and Home Safety (IBHS), translates decades of scientific research into practical standards for improving the resilience of homes and buildings. By focusing on predictable failure points, especially in roofing systems, and by promoting third-party verification and documentation, Fortified offers a clear pathway to reducing losses, accelerating recovery, and ensuring that investments in sustainability and efficiency are matched by investments in durability and safety.

The Scope of the Challenge

Between 2020 and 2024, the United States experienced over $750 billion in damages from a range of natural disasters—wildfires, hurricanes, tornadoes, derechos, severe thunderstorms, and, notably, hail. The impact of these events extends well beyond financial loss: they displace families, disrupt communities, and strain public and private resources. Insurance companies, who shoulder much of the recovery cost, have driven research into how homes fail and what can be done to prevent such failures. This has led to a focus on actionable standards and practical solutions, aimed at investing modestly up front to avert far greater losses later.

The IBHS research center stands at the forefront of this science, with capabilities to simulate hurricane-force winds, create realistic hail, and conduct full-scale residential and commercial building tests. The findings from these experiments are clear: roofs are the most common and most critical point of failure. When roofs fail, the resulting damage can cascade through the entire structure, often rendering homes uninhabitable and leading to extensive, costly repairs. Despite this, roofs remain one of the least inspected and least enforced elements in building codes across much of the country.

From Research to Action: The Fortified Program

The Fortified program addresses these challenges with a systems-based, research-driven approach to home resilience. It is designed to be voluntary, scalable, and applicable to a wide range of buildings—from single-family homes to multifamily and commercial structures. Fortified is not a warranty or insurance policy, nor does it guarantee zero damage; rather, it is a method for reducing the frequency and severity of loss, accelerating recovery, and providing peace of mind for property owners.

Fortified standards are organized into three main levels:

  1. Fortified Roof: The foundational level, focusing on keeping the roof intact and water out of the home. Key requirements include enhanced deck attachment, sealing the roof deck, and securing the roof edges with drip edge and starter strips.
  2. Fortified Silver: Building on the roof level, Silver addresses damage amplifiers—components such as garage doors, openings, porches, and gable ends that, if compromised, can lead to catastrophic structural failure.
  3. Fortified Gold: The highest level, requiring a fully continuous load path from the roof to the foundation, and design pressure verification for openings and structural sheathing to ensure the entire building envelope is resistant to extreme pressures.

Hazards Addressed and Regional Variations

Fortified standards differentiate between hurricane-prone and high-wind regions. While the program does not address flooding (which is typically managed by federal programs), it does provide optional supplements for hail resilience—a critical concern in many inland regions. Most tornadoes, for example, are in the EF0-EF2 range, and Fortified standards can significantly reduce damage and displacement even in these events. In documented tornado outbreaks, applying Fortified standards has been shown to reduce the area and severity of damage by 40–65% in affected zones.

Technical Details: Roofing, Attachments, and Materials

The Fortified approach to roofing centers on details that are often overlooked but make a profound difference in resilience.

  • Deck Nailing: Using ring shank nails at 4 inches on center, rather than the wider spacings found in some codes, doubles the uplift resistance of the roof deck for a relatively small additional cost.
  • Sealed Roof Deck: Applying approved tape or membranes over deck seams can keep up to 95% of water out of the attic, as demonstrated in comparative laboratory tests. This simple step can prevent the equivalent of multiple bathtubs of water from entering a home during a roof-cover loss.
  • Edge Securement: Fortified standards require drip edge over the underlayment and secure nailing patterns, along with fully adhered starter strips or flashing cement, to create a continuous load path and seal out wind and water.
  • Roof Coverings: For shingles, Class F or H wind ratings are required. For other materials (metal, tile, low-slope roofs), third-party testing to site-specific design pressures is essential. Hail-prone regions may opt into a supplement requiring shingles with demonstrated resistance to realistic ice-ball impact, as tested by IBHS.

Material agnosticism is a hallmark of the Fortified program; the focus is on performance and verified testing, not brand or specific product. Proper installation, as always, is critical—metal roofs, for example, may perform very well or very poorly depending on how they are attached and flashed.

Beyond the Roof: Garage Doors, Openings, and Load Paths

Failure of a garage door under wind pressure can lead to catastrophic damage, including roof deck loss and wall collapse. Fortified Silver requires pressure-rated garage doors, and in hurricane zones, impact-rated windows and doors. Porches and attached structures must be securely anchored, and gable end bracing is required to prevent wind-driven failures.

At the Gold level, continuous load path requirements ensure that the forces of wind are transferred from the roof through the walls and into the foundation, minimizing the risk of structural separation or collapse. This is especially important in hurricane-prone areas, where pressures are highest and failure can be most destructive.

Verification, Documentation, and the Role of Evaluators

A unique strength of the Fortified program is its emphasis on third-party verification. Independent evaluators document every step of the process, from material selection to installation and fastening patterns, using geotagged photographs, manufacturer documentation, and compliance forms. This rigorous approach ensures that the intent of the standard is met in the field and provides a verified record for property owners, builders, and insurers.

The designation, valid for five years, is tied to the property address and is fully transferable between owners. Renewal requires confirmation that the roof and critical systems remain in compliant condition and that no unverified modifications have been made.

Retrofit vs. New Construction

While Fortified Gold is most commonly achieved in new construction, Silver and especially Roof-level designations are accessible for existing homes, particularly during re-roofing projects. Gut rehabs or post-disaster rebuilds may achieve higher levels if documentation and access permit; however, the majority of retrofits focus on the most impactful, accessible upgrades such as roof deck enhancements and garage door replacements.

Application to Multifamily and Commercial Structures

Fortified standards extend to multifamily and commercial buildings, with adaptations for building type and function. Additional requirements may apply, such as elevated mechanicals in flood-prone areas and backup power provisions for critical commercial operations. Evaluation for these structures is typically managed by risk engineering firms rather than individual evaluators, but the principles remain the same: systems-based, performance-verified resilience.

Incentives, Grants, and Growing Adoption

A growing number of states—including Alabama, Louisiana, North Carolina, South Carolina, Oklahoma, Kentucky, and Maine—now offer grants or insurance premium discounts to encourage Fortified construction. For example, Alabama provides up to $10,000 for homeowners to re-roof to Fortified standards, and Louisiana is implementing mandatory premium discounts. Federal and regional grant programs, such as those through the Federal Home Loan Bank, are increasingly tied to resilience standards like Fortified, especially for affordable and multifamily housing.

Private insurance carriers, too, are offering endorsements or premium reductions for Fortified homes, recognizing the proven reduction in claims frequency and severity. In hurricane Sally, for instance, Fortified homes were 70% less likely to file a claim than traditionally built homes, and average claim amounts were reduced by over 20%.

Performance in the Real World

Field evidence strongly supports the efficacy of the Fortified approach. After major storms, including hurricanes and tornadoes, homes built or retrofitted to Fortified standards consistently outperform their conventional counterparts. The difference is not only in the reduction of damage but in the speed of recovery—families are able to return to, or remain in, their homes much sooner, reducing displacement and community disruption.

Integration with Sustainability and Energy Efficiency

Resilience and sustainability are not competing priorities. In fact, resilient construction is essential for ensuring that investments in energy efficiency and green building are not rendered moot by disaster-related displacement or damage. Material choices—such as the use of ice and water shield, closed or open cell foam, or specific roof coverings—must be balanced for both resilience and building science best practices, including the avoidance of trapped moisture and adherence to manufacturer and code requirements.

Professional Training and Resources

For builders and contractors, the Fortified program offers accessible online training and certification, particularly for roofers. Design professionals, evaluators, and contractors can all access technical documents, CAD-ready details, and checklists to streamline compliance and documentation. As adoption grows, more manufacturers are aligning their products and systems with Fortified requirements, making it easier to specify and install compliant assemblies.

Key Takeaways

  • Roofing is the critical first line of defense against wind, hail, and water intrusion; details in fastening, sealing, and edge protection are essential.
  • Fortified standards are systems-based and scalable, addressing predictable failure points from the roof to the foundation.
  • Documentation and third-party verification are crucial to ensuring compliance and performance.
  • Retrofit opportunities exist, especially at the roof and Silver levels, making resilience upgrades accessible for existing homes as well as new construction.
  • Fortified homes experience fewer and less severe insurance claims and recover more quickly after disasters.
  • Incentive programs and insurance discounts are expanding rapidly, making resilience upgrades more affordable.
  • Proper installation and adherence to tested, verified assemblies are more important than any specific material choice.
  • Integration of resilience with green building and energy efficiency ensures long-term sustainability and occupant safety.
  • Professional training and resources are available to support implementation and verification.

Green Home Institute is committed to promoting best practices in sustainable, resilient, and healthy home construction. For technical details, training, and further information on the Fortified program, professionals are encouraged to consult the IBHS and Fortified Home resources.

Q & A

1. Are DWG files for standard detail sets available, or are only PDFs provided?

Answer:
Yes. While there is a PDF ‘pack’ containing all the standard detail sets, you can also find individual DXF and DWG files just below that section on their website. DWG and PDF versions are available here: https://fortifiedhome.org/2025-technical-documents/


2. Is open cell sprayed foam acceptable under the ice shield method, or is only closed cell not recommended?

Answer:
IBHS does not verify the type of foam insulation if foam is present, but it is not recommended to use ice and water as the sealed roof deck method if closed cell foam exists, due to moisture trapping concerns. Open cell foam is less likely to trap moisture; however, it’s important to consider the entire building envelope as a system and manage risks accordingly.


3. Has IBHS researched the adherence of shingles installed with air nailers versus hand-nailing?

Answer:
IBHS has not conducted testing on shingle adherence comparing air nailers to hand-nailing. Their post-event studies have observed roof cover loss at wind speeds as low as 60 mph. This led to the development of FORTIFIED Roof to minimize loss, even if the cover is lost.


4. Is there a real-world difference in structural performance between wall sheathing installed directly against the wall and Zip-R sheathing with continuous exterior insulation?

Answer:
The key to performance in any sheathing application is involving an engineer in the design for the specific site conditions (wind speed, exposure, etc.). The engineer will specify the product type and installation to meet those conditions and ensure performance in extreme wind events. Correct installation is crucial; improper installation can impact performance even with good engineering.


5. For edge flashing at the eave, should it go on top of or under the moisture barrier? How should this be addressed in drawings?

Answer:
The key to the edge detail is considering the entire system. The drip edge-over-underlayment detail serves as an anchor point for the shingle starter strip, which should be a peel-and-stick starter meeting ASTM D1970 or be set in an 8″ wide, 1/8″ thick layer of mastic for sealing. In areas where local code hasn’t caught up with FORTIFIED requirements, an 18″ strip of ice and water shield may be installed to cover the drip edge-over-underlayment joint. Florida Building Code requires the full FORTIFIED system, and most shingle manufacturers reference this system in their documentation.


6. What are the recommendations for attaching solar panels to roofs without compromising the roof?

Answer:
To maintain a FORTIFIED designation with solar panels, ensure the solar array and installation are designed by an engineer for the site conditions, are installed according to the engineer’s design, and that the installation is well documented. Proper flashing of any roof penetrations is essential. Further details are in the 2025 FORTIFIED Standards.


7. Is there a FORTIFIED document for solar panel installation?

Answer:
Yes. FORTIFIED requires that roof-mounted solar panels be properly flashed to prevent leaks and to minimize damage risk in high winds. Attachments must be engineered for the site. More details are available here: https://fortifiedhome.org/article/dont-jeopardize-your-homes-resilience/


8. Is FORTIFIED roofer training available virtually, or only for professionals?

Answer:
All FORTIFIED trainings are online and broken into self-paced modules. Information on certification training and prequalification is available at: https://fortifiedhome.org/how-to-become-fortified-certified/. Be sure to read the training handbooks for details.


9. Can a home be designated FORTIFIED if it was built to those standards but lacks documentation?

Answer:
No. One of the keys to FORTIFIED designation is third-party verification and documentation gathered during construction by a FORTIFIED Evaluator. Without documentation, a designation cannot be issued.


10. Will IBHS test innovative materials that claim improved uplift performance?

Answer:
While IBHS welcomes innovation, they are not a product testing facility and rely on existing labs and standards referenced in the FORTIFIED standard. New products should be tested through the established product testing pathways.


11. What is the U-factor of impact-protected windows and doors in FORTIFIED Silver and Gold designs?

Answer:
IBHS does not generally track U-factor details for windows and doors in FORTIFIED designs. Sourcing energy-efficient, impact-rated products that also meet local codes can be challenging. As an alternative, a tested shutter system may be used for some projects.


12. Is the closed cell foam option below the sheathing still available for BRONZE designation on relatively new roofs?

Answer:
Yes, the closed cell foam option remains available for homes with roofs in new or good condition. Details can be found in Technical Bulletin 2015-04: https://fortifiedhome.org/wp-content/uploads/FH-2015-04-Sealed-roof-deck-supplemental-deck-attachment-v2.pdf?v=1778018228070


13. Can IBHS contact Olympus Insurance regarding solar and FORTIFIED endorsements?

Answer:
More information and context would be needed to address this question. If you can provide additional details, a more specific response may be possible.

*Content created by a human speaker, transcribed by Zoom, and arranged by an AI LLM