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Author: Brett Little

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The Affordable Path to 120V Cooking

Recently, Sazi Bugay and Emily Intravia joined us for the weekly Wednesday free CEU webinar to talk about The Affordable Path to 120V Cooking.

We captured the recording of this webinar for you to watch, an article based on the transcript if you prefer to read it, additional Q&A not answered during the session, and a survey summary of the attendees.

Attendees learned that induction cooking is much more efficient and safer than traditional gas or electric ranges, with new 120V induction models like those from WattSipper making it possible to use induction technology in older homes and apartments without major electrical upgrades. These ranges use power sharing between the cooktop and oven, often only requiring an upgrade to a 20-amp outlet—an affordable change that may be offset by rebates and incentives that are still available. The webinar highlighted how induction ranges save energy, offer environmental benefits, and provide features such as better insulation, improved safety, and compatibility with common cookware like cast iron. Participants also appreciated learning about the practicalities of switching to induction, the importance of magnetic cookware, the continued push for more efficient kitchen appliances, and how these innovations make induction accessible for more households, especially in multifamily and older buildings.

This article explores the transformative potential of 120-volt induction cooking technology in the context of residential electrification. Drawing from the expertise of Sazi Bugay and Emily Intravia, it examines the challenges of upgrading legacy housing stock, the technical and practical aspects of 120V induction ranges, and the broader implications for health, efficiency, and sustainability. The discussion is aimed at housing professionals, builders, and contractors, with accessibility for the general public, offering a technical yet approachable overview of how low-power induction appliances can accelerate the transition away from gas cooking without costly electrical upgrades.

The Affordable Path to 120V Induction Cooking: Electrifying American Homes Without Major Upgrades

Introduction

Electrification of the U.S. housing stock stands as a pivotal step in decarbonization and indoor air quality improvement. While advances in heat pump technology for HVAC and water heating have made significant inroads, the kitchen—specifically, cooking appliances—remains one of the final hurdles for widespread electrification. The dominance of gas cooking, especially in older homes with limited electrical capacity, presents both cultural and technical challenges. Yet, recent developments in 120-volt induction ranges offer a pragmatic, affordable, and health-conscious solution for both multifamily and single-family residences, enabling a plug-and-play path to all-electric kitchens.

The Challenge: Legacy Housing and Electrical Constraints

The United States is home to approximately 140 million housing units, with 40% built before 1980. Many of these structures rely on 60-amp electrical panels and gas connections standard in that era. While upgrades such as heat pumps for both water and space heating have become more accessible, transitioning to electric cooking has historically required costly service panel upgrades and new 240V circuits—an often prohibitive barrier for property owners and tenants alike. The cost of such upgrades, especially in states like California and New York, can reach several thousand dollars, making electrification unattainable for many.

Induction Cooking: A Technical Overview

Induction cooking utilizes electromagnetic fields to directly heat compatible cookware, offering speed, efficiency, and safety advantages over both gas and traditional electric (radiant or coil) cooking. Unlike gas, induction does not emit combustion byproducts, and unlike radiant electric, it delivers heat directly to the pan, minimizing wasted energy. Surveys indicate that about 80% of home cooking takes place on the cooktop, with ovens being used primarily during holidays and special occasions. Induction cooktops respond quickly to temperature adjustments, provide precise control, and remain cool to the touch, reducing burn risk and making them especially safe for families and older adults.

The 120-Volt Solution: Engineering for Retrofit

The innovation of 120V induction ranges lies in their ability to work within the electrical constraints of older homes. Most U.S. residences have 15- or 20-amp circuits in kitchens. The new generation of 120V induction ranges is designed for 20-amp outlets (drawing up to 1800 watts), with future possibilities for 15-amp versions. This design enables direct replacement of gas or electric ranges without panel upgrades, hardwiring, or extensive permitting. For property managers and housing authorities, this means lower installation costs, minimal disruption, and broad compatibility with existing infrastructure.

Dynamic power allocation is a defining feature: these ranges intelligently share available power between the cooktop and oven cavity. Since simultaneous high-demand use of all burners and the oven is rare in typical households, this “smart sharing” provides ample functionality for daily cooking while staying within safety and code requirements.

Efficiency, Safety, and Health Benefits

Induction cooking is the most efficient residential cooking technology currently available. While gas cooking delivers less than 40% of its energy to the food, induction can achieve 90-95% efficiency. This translates to faster boiling times, reduced waste heat in the kitchen, and lower utility bills. The induction surface itself remains relatively cool, and recent UL safety standards now require oil temperature sensors to prevent overheating and potential fires—a significant advancement in kitchen safety.

From a health perspective, eliminating gas combustion in the home directly improves indoor air quality, reducing exposure to nitrogen dioxide, carbon monoxide, and particulate matter. For multifamily buildings, this is especially valuable, as shared ventilation and high tenant turnover can exacerbate the risks associated with gas appliances.

Practical Considerations: Sizing, Installation, and Maintenance

Modern 120V induction ranges are available in standard American sizes (20, 24, and 30 inches), making them suitable for everything from compact apartments to family kitchens. Oven cavities, typically ranging from 2.5 to 3 cubic feet, accommodate full baking sheets and even large turkeys, addressing concerns about functionality for holiday cooking.

Installation is straightforward: these ranges are truly plug-and-play, requiring only a standard dedicated 20-amp circuit. Compared to the $6,000–$12,000 cost of a full panel and circuit upgrade, swapping a single outlet is a minimal investment. Maintenance is simplified by modular designs using standard electrical components, and cleaning is easier thanks to flat glass surfaces and steam-clean oven options.

Cookware Compatibility

Induction cooking requires pots and pans with magnetic (ferrous) bases. Today, most cookware is labeled as induction-compatible, including stainless steel, cast iron, and many ceramic-coated options. A simple magnet test can confirm compatibility. For property owners concerned about tenant transition, starter cookware sets can accompany new installations, smoothing the adoption curve.

Comparing Induction, Gas, Radiant Electric, and Microwave Cooking

Time-to-boil comparisons reveal that 120V induction is competitive with gas and significantly faster than radiant electric, especially at lower wattages. The direct heat transfer of induction reduces ambient heating—a key consideration in small apartments or in warm climates. While microwaves are efficient for reheating, their limitations in real cooking and food quality make induction the preferred choice for healthy, versatile meal preparation.

Addressing the 15-Amp Dilemma

While the current generation of 120V induction ranges is optimized for 20-amp circuits, many older homes have only 15-amp outlets. Upgrading a kitchen outlet to 20 amps is a comparatively minor electrical job and is often incentivized by state or local programs. This modest investment is far less costly than upgrading to 240V service for conventional electric ranges.

Incentives and Policy Context

Rebates and incentives play a crucial role in accelerating adoption. Federal programs, such as those created under the Inflation Reduction Act, offer substantial rebates for induction ranges—up to $840 for qualifying households. Some states and utilities (notably in California and New York) provide additional rebates, and new policies are emerging to support electrification of affordable and multifamily housing. However, evolving federal guidelines may limit certain types of fuel-switching rebates after 2026, underscoring the urgency for early adoption and careful project planning.

Environmental and Social Impacts

Transitioning to 120V induction ranges supports wider decarbonization efforts, reducing greenhouse gas emissions and fossil fuel dependence. For property managers, the benefits extend to easier maintenance, improved resident health, and compliance with emerging building codes. For residents, especially in dense urban areas, electrification means quieter, cooler, and safer kitchens.

Looking Ahead: Market Adoption and Future Directions

Europe leads the world in induction cooking adoption, with over 65% of households using induction cooktops. In the U.S., this number remains low but is poised to grow rapidly as affordable, compatible products become widely available. As more builders and contractors embrace these technologies, the supply chain will diversify, costs will decrease, and consumer familiarity will increase.

Manufacturers are prioritizing accessibility features such as front-mounted controls for ADA compliance, and are designing appliances to fit shallow cabinets and tight spaces found in older urban housing. The shift to 120V induction cooking is not just a technical upgrade but a rethinking of how kitchens can be healthier, more efficient, and more resilient for all.

Q&A Discussion

Q: Are 120V induction ranges compatible with 15-amp circuits, or is a 20-amp outlet required?
A: Current models require a 20-amp outlet, drawing up to 1800 watts. Upgrading a 15-amp outlet to 20 amps is a straightforward and affordable electrical job, much less costly than installing a 240V circuit.

Q: How does 120V induction performance compare to 240V induction and traditional gas ranges?
A: While 240V induction offers the shortest boiling times, 120V induction is highly efficient and competitive with gas for most daily cooking. The difference in speed is noticeable primarily when all burners are used at maximum power, which is rare in typical use.

Q: What about cookware compatibility?
A: Induction requires magnetic cookware. Most modern pots and pans are labeled as induction-friendly. If a magnet sticks to the base, it will work. Cast iron, stainless steel, and many ceramic-coated pans are compatible.

Q: Are there safety concerns with induction cooking?
A: Induction is among the safest cooking technologies. Surfaces remain cool, and new UL standards require oil temperature sensors to prevent fires. Units also feature automatic shutoff and pan detection, further reducing risks.

Q: Can all burners be used on high at the same time?
A: Smart power management limits total output to remain within circuit safety limits. While all burners can be used, full power may not be available simultaneously; the range will allocate power dynamically.

Q: What is the typical oven size, and can it accommodate large meals?
A: Oven cavities in 120V induction ranges range from 2.5 to 3 cubic feet, sufficient for standard baking sheets and large roasts (e.g., a 20-pound turkey).

Q: Are rebates available for these appliances?
A: Substantial rebates are available at federal, state, and utility levels. Details vary by location and income eligibility, so check local resources for current programs.

Q: What about maintenance and service?
A: 120V induction ranges are designed with standard components for easy maintenance, and cleaning is simplified by flat surfaces and enamel oven cavities. No battery maintenance is required.

Q: Is Wi-Fi or smart connectivity required?
A: No. While smart features can be added, most models focus on simplicity and reliability, avoiding unnecessary connectivity that can complicate turnover in rental properties or raise privacy concerns.

Q: What is the price range for 120V induction ranges?
A: Prices typically range from $1,500 to $2,300 before rebates, depending on size and features. Multifamily projects may access bulk purchasing and additional incentives.

Q: What is the easiest way to recognize a NEMA 5-20R receptacle?
A: The easiest way to recognize a NEMA 5-20R receptacle is by its distinctive “T-slot” configuration. While a standard 15-amp home outlet has two parallel vertical slots, the 5-20R includes a horizontal cutout branching off one of the vertical slots. This design allows it to accept both standard 15-amp plugs (NEMA 5-15P) and dedicated 20-amp plugs (NEMA 5-20P), which feature one horizontal prong. Note: Must use 12AWG wire (not common 14 gauge).

Q: What are the installation requirements for a Wattsipper range?
A: For best results and proper operation, a dedicated 20 Amp circuit and a NEMA 5-20R receptacle behind the range are required. Safety certification of the unit through a regulatory CB has been provided with this condition, and information on the requirements is given both at the website and in the product documentation.

Q: Would you compare induction cooking to microwave cooking?
A: Induction cooking creates magnetic waves to heat the ferrous pot or pan, which in turn cooks the food inside the vessel. Microwave cooking, on the other hand, uses microwaves generated by a magnetron to penetrate the food in a non-metal dish, energizing the water molecules to create heat and cook the food.

Q: Where can we find documentation to verify the figure that approximately 140 million homes were built before 1980?
A: Total housing stock in the US is 140 million (including single-family and multifamily residential units) and nearly 50% of this stock was built before 1980. Source: NAHB Blog – How Old is Today’s Housing Stock (2026)

Q: What’s the cubic foot capacity of the inside oven?
A: Depending on the size and series, cooking cavity volume ranges from 1.9 cu ft (20″) to 2.9 cu ft (30″). Please consult the website for each unit: https://www.wattsipper.com/products

Q: What are the merits of induction vs. microwave cooking (efficiency, cost, etc.)?
A: Induction cooking is the safest, fastest, and most efficient open surface cooking method currently available. It directly heats the vessel, transferring up to 95% of the energy to the food. Other methods are less efficient and can produce excess heat and harmful gases. Microwave cooking is also very efficient but may raise health concerns as microwaves energize and can degrade water molecules in food, potentially affecting food quality and taste.

Q: Gas ranges being replaced typically have 15-amp outlets. Is an electrician needed to install a 20-amp plug for a Wattsipper range?
A: Yes, electrician work is needed to update the electrical connection to a 20 Amp circuit. Although Wattsipper ranges never exceed 15 Amps of max draw, UL safety requirements mandate a dedicated 20 Amp circuit.

Q: How is the heat distribution with titanium cookware?
A: Pure titanium will not work with induction. It must be blended with a ferrous alloy to be magnetizable, but this results in a very expensive alloy compared to basic stainless steel.

Q: Can the sensors on an induction oven be wireless to provide warnings or alerts to a smartphone?
A: Induction cooktop glass must have dedicated sensors and Bluetooth or WiFi connectivity for notifications. Many manufacturers use WiFi for this. Wattsipper does not use connected appliance technologies due to ongoing safety discussions.

Q: Are there “convertible” induction products for boating, RV, van-life, or tiny home markets?
A: Wattsipper ranges will be offered in both RV and boat configurations. The company is working on alternative models. All models draw 1,800W (15 Amp) maximum and come with a 5-piece starter induction-ready pan and pot set; Heritage series include a cast iron griddle.

Q: Is there noise from the Wattsipper range, like fans or squealing as with countertop induction burners?
A: Wattsipper ranges have a cooling fan for induction operation, and a separate internal fan for oven use above 300°F. The DC-controlled cooling fans create minimal noise, and due to DC operation, buzzing is minimized or unnoticeable.

Q: What are the length, depth, and width measurements?
A: All product specifications for the 19 Wattsipper models are at: https://www.wattsipper.com/products

Q: For an older 60-unit co-op with electric kitchens, should we replace current electric ovens with Wattsipper ranges to save energy? Replace as they fail or all at once?
A: Wattsipper ranges consume roughly 1 kWh of energy per hour (3,412 BTUs). Gas ranges have 8-9 times higher BTU power for the same period. It is recommended to convert all 60 ranges to Wattsipper for efficiency and safety, particularly since 80% of cooking is done on the cooktop.

Q: How much does electric cooking contribute to my monthly bill?
A: The average US home consumes 875 kWh/month (10,500 kWh/year) at 1,800 sq ft. Only 2% of this is used for electric cooking.

Q: All these features and a cook set included seems expensive. What is the expected cost?
A: All Wattsipper ranges include a 5-piece induction-ready high-grade stainless steel pan and pot set.

Q: Does the oven come in a wall version?
A: Yes, a wall oven with 2.5 cu ft volume for 120V operation is available under the Summit brand: https://www.summitappliance.com/catalog/model/SEW24115V2P

Q: Can you use all burners at high setting simultaneously?
A: Wattsipper ranges have a power share feature; maximum total power is 1,800W. If all 3 zones are set to max, 1,800W is shared equally (600W each).

Q: Do these products have a male T plug to encourage safe NEMA 20amp receptacle installation? Is there a safety feature to prevent improper wiring upgrades?
A: All Wattsipper ranges come with a pre-installed T-shape NEMA 5-20P power plug.

Q: Is a 12-pound turkey the typical size for most people? Can the oven handle larger birds?
A: Typical store turkeys are 12-15 lbs, with XL up to 20 lbs. Wattsipper ranges can handle XL turkeys with proper pans.

Q: Can standard dial locks work on Wattsipper stoves?
A: Yes, standard dial locks work for child safety. Additionally, all cooktops include an electronic child lock feature.

Q: Do you have a photo of the inside of the bottom drawer?
A: Please refer to each product page: https://www.wattsipper.com/products

Q: What is the approximate cost of a 30” Wattsipper range?
A: The top-of-the-line 30″ Wattsipper range is $2,850.00 MSRP. For projects and multi-unit purchases, expect under $2,500.

Q: I’m getting a CAPTCHA verification prompt when requesting a quote on your website, but it does not appear. What should I do?
A: Please retry; it should be working.

Q: Are there rebates or tax credits for these ranges? Does income or taxpayer status matter?
A: There are numerous incentives for induction ranges. Visit https://incentives.wattsipper.com/incentive-finder for details.

Q: Are Wattsipper ranges available in Canada and are there rebates?
A: Contemporary Series are approved and registered for Canadian use with NRCAN. Once products are rolled out, Canadian contacts will be notified. For more information: https://www.wattsipper.com/

Key Takeaways

  • 120V induction cooking enables affordable, plug-and-play electrification of kitchens in legacy housing without major electrical upgrades.
  • Induction technology is safer, more efficient, and healthier than gas or traditional electric cooking, with substantial indoor air quality benefits.
  • Dynamic power allocation and smart design allow these ranges to function effectively on standard 20-amp circuits, with oven and cooktop sharing available power.
  • Most modern cookware is compatible with induction; providing starter sets can ease the transition for tenants and owners.
  • Installation is straightforward and minimally disruptive, making this solution ideal for multifamily and older single-family homes.
  • Rebates and incentives are widely available but may change after 2026; early action can maximize savings.
  • Induction ranges are available in multiple sizes and ADA-compliant designs, supporting broad adoption across housing types.
  • Maintenance is simplified by standardized components and easy-clean surfaces; no battery replacement is required.
  • The transition to induction supports decarbonization, lowers bills, and improves residents’ health and comfort.
  • U.S. adoption is expected to accelerate as awareness, incentives, and product availability increase.

 

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Why Select A Green Realtor?

We recently welcomed member Jan Green to our Weekly Wednesday Webinar CEU series.

Below, you can find the recording of that talk, an article based on the recording, the attendee survey summary, and additional Q&A from the webinar.

Webinar attendees reported learning a wide range of new information about green realty and sustainable home features. Many participants were surprised to discover the existence of green realtor certifications, such as the NAR Green Designation and Pearl Certification, as well as the relatively small number of realtors currently holding these credentials. Attendees learned about the various professionals and roles involved in selling a green home, the importance of working with knowledgeable inspectors, and resources like the Green Building Registry and Active Rain. The session also highlighted the value of energy audits, the life expectancy of green components, and how green features can be clearly described and valued in property listings to attract buyers.

This article explores the vital role of green realtors in advancing sustainable practices within the residential housing market. Drawing from the expertise of a leading green-designated realtor, it provides an in-depth look at what defines a green realtor, the value of energy-efficient and high-performance homes, the complexities of marketing and appraising green features, and practical guidance for housing professionals and the public alike. The discussion is grounded exclusively in the insights and case studies presented in a recent educational session, highlighting both technical details and accessible explanations for a broad audience. The article concludes with a Q&A segment derived from audience interaction, followed by a summary of key takeaways.

The Critical Role of Green Realtors in High-Performance Home Transactions

Introduction

Designing, building, and renovating green homes are all important, but the impact of these efforts is limited if the value and benefits of high-performance, sustainable housing cannot be communicated effectively to buyers and sellers. The challenge lies not only in the technical aspects of sustainable construction but also in bridging the knowledge gap between the professionals who create these homes and the broader market that must understand and embrace them. This article examines the unique perspective and practices of green-designated realtors, focusing on their essential role in educating, marketing, and facilitating the successful sale of sustainable homes.

What Is a Green Realtor?

A green realtor is distinguished by formal education and credentials in sustainability and high-performance housing. Designations such as NAR Green, EcoBroker, and certifications like LEED Green Associate or WELL AP indicate a commitment to ongoing learning and a business model that integrates people, planet, and profit. These professionals approach real estate transactions with a focus on sustainability, always considering the environmental and health impacts of homes, as well as their economic benefits.

Green realtors are adept at sourcing specialized trades, working with appraisers familiar with high-performing homes, and employing a different methodology than conventional practitioners. Their expertise is often sought after by peers for education and for elevating industry standards. For instance, they possess the skills to calculate the value of owned solar systems for listing prices, utilizing tools like PVvalue.com.

The Business Case for Energy Efficiency

Energy efficiency in homes is profitable, but the beneficiaries vary. Builders, trades, and vendors may receive rebates, incentives, and sometimes tax credits, while homeowners typically benefit through utility savings and, potentially, higher appraisals. However, the communication and realization of this value depend heavily on the knowledge and actions of the realtor.

Many realtors lack familiarity with energy efficiency and sustainable features. Nationwide, only a small fraction have earned green designations; in Arizona, for example, fewer than 100 out of over 88,000 realtors possess such credentials. This knowledge gap often leads to missed opportunities in marketing, valuation, and buyer education.

Core Responsibilities of a Green Realtor

Educating Clients and Industry

Green realtors play a continual educational role, informing clients, peers, and the public about the benefits and specifics of high-performance housing. They clarify what makes new or retrofitted homes energy efficient, interpret certifications and ratings, and explain the relevance of local and national programs. In Arizona, for example, programs like the Scottsdale Green Building Program and Pearl Certification offer third-party verification of performance.

Navigating the MLS and Marketing Green Homes

Green realtors maximize the visibility and value of sustainability features by leveraging Multiple Listing Service (MLS) tools. They understand the importance of accurately listing features such as Energy Star appliances, SEER ratings, insulation levels, renewable energy systems, water-saving fixtures, and indoor air quality improvements. Features must be documented clearly and, where possible, with dates of installation and cost, as appraisers cannot assign value without such detail.

Marketing strategies are tailored to highlight energy efficiency in public remarks, photographs, and documentation tabs, always mindful of the limitations and rules specific to each MLS. The placement and wording of green features are strategic, as studies have shown buyers focus primarily on the first sentences of property descriptions.

Addressing Greenwashing and Liability

A persistent challenge is greenwashing: the overstatement of environmental benefits or mislabeling of features. Green realtors take care to avoid broad, unsubstantiated claims, instead providing specific, fact-based descriptions. They also clarify distinctions between realtors and real estate agents, particularly regarding the use of professional designations and the associated ethical obligations.

Advising on Home Upgrades and Retrofits

When advising clients on upgrades, green realtors advocate for a “start small” approach, focusing first on practical improvements such as insulation, duct sealing, efficient HVAC systems, and water-saving devices before considering larger investments like solar panels. They emphasize the importance of energy audits to identify the most cost-effective measures and to provide a roadmap for future improvements.

Spotting Red Flags in Resale and Retrofit Homes

Green realtors are trained to identify potential issues in both new and retrofitted homes, from missing insulation in room additions to indoor air quality problems related to mold, asbestos, or volatile organic compounds. They utilize historical listing data, infrared imaging, and collaboration with home inspectors to uncover hidden defects that could impact comfort, safety, or efficiency.

Appraising and Valuing Green Features

The appraisal of high-performance homes remains a complex issue. Green features, including owned solar systems, upgraded insulation, and advanced HVAC, require thorough documentation to be considered in valuation. Appraisers must be qualified—ideally certified in green appraisal practices—and provided with detailed lists of features, specifications, and utility data.

Tools such as the Residential Green and Energy Efficient Addendum and PVvalue.com are essential for substantiating claims and assigning value to specific upgrades. However, leased or financed solar panels generally do not contribute value in appraisals due to legal and title constraints.

Realtors play a proactive role by contacting lenders early in the transaction to request green-certified appraisers, preparing comprehensive documentation, and educating all parties involved about the nuances of valuing high-performance homes.

Case Studies: Real-World Impact

The article includes examples of successful transactions where green realtors have added value through careful documentation and marketing of sustainability features. In one case, a home that previously failed to sell was relisted with detailed feature lists and supporting documentation, resulting in a sale at the appraised value. These successes underscore the importance of preparation, transparency, and collaboration among realtors, appraisers, and clients.

The Future of Green Real Estate

The housing market is evolving, with increasing demand for transparency, efficiency, and sustainability. Tools like the U.S. Green Building Registry and evolving software standards (such as UAD 3.6) are making it easier to track and communicate green features. Nonetheless, the expertise of green realtors remains critical in translating technical details into market value and in overcoming persistent barriers in the appraisal and sales process.

Green realtors also advocate for ongoing education within the profession, encouraging peers to pursue green designations and to stay current with innovations in building science, marketing, and policy.

As for realtors providing a HES score to clients – it would be a better idea for them to earn a green designation first to have a base of knowledge and to understand the terms and benefits of features.  By earning a GREEN designation first, they stand a better chance of understanding the terms used in a HES and providing useful information to clients.  They would also be more included to recommend a HES score for a homeowner.  Remember, realtors are sales people not trained in EE.  If no one is offering HES in AZ, it’s less likely a realtor would seek that kind of information. 

Estimating the number of solar panels needed to charge an EV can be difficult. You’d need a full year of utility bills to understand how your EV’s energy use changes with the seasons.

In Arizona’s extreme heat, we use a lot more electricity and often charge daily when we’re showing homes back-to-back. On 115-degree days, the air conditioning runs before, during, and after appointments. Because our service area spans about 500 square miles, we may need to charge every day—unlike in the winter, when we enjoy much milder weather.

EV energy use isn’t consistent throughout the year, so there’s no reliable year-round average.  Besides, a realtor may sell 10 homes one year and 20 the next.

Visit this link to search for a green certified appraiser.  Make sure to click on the state so they are in Alpha order.  Share that list when seeking a green appraiser.

https://ai.appraisalinstitute.org/eweb/Dynamicpage.aspx?webcode=AIPDPDirectory&key=428cdb90-9814-47e4-9256-a4113c815862

For the survey and response: 

Adding education green designations to my business has been a huge asset. Clients value additional knowledge, and I feel it helps build trust. They’re reading testimonials more often, and several have found me through AI—not just through my most recent sale in Phoenix.

In January, I’ll be selling a $2.3 million home referred to me by a local Realtor who has retired. After 15 years of seeing the knowledge I’ve shared, she trusts me to take good care of her clients.  The Canadian seller has researched me and feels comfortable selling his home remotely.  The seller works in IT so I’m sure he’s vetted me extensively.  Trust is huge in real estate.

This retired agent could have easily referred this client to anyone else, and she knows many in the real estate industry.  But she chose me over other realtors.  It’s advanced knowledge and others see it as an asset above a traditional agent, not just that I’ve sought and earned green credentials.  It’s the level of expertise in real estate and /knowledge that is seen as an advantage over other agents.

Please clarify that the Residential Green & Energy Efficient Addendum was created and shared live on the Appraisal Institute website in about June 2010.  The UAD 3.6 software is going live on 11/2/26, depending on software availability. 

Every person passing the real estate exam in their respective state is a real estate agent.  Only those becoming members of the National Association of REALTORS® become REALTORS®.  REALTORS® subscribe to NAR’s strict Code of Ethics and benefit from education and credentials, including the GREEN designation.

Follow up summary:

The U.S. housing market has never offered such a wide range of homes. It’s up to industry professionals to stay educated and informed so they can best serve the public.

Before choosing a real estate agent, buyers and sellers should interview them. Ask how many homes they sell each year, what advanced education they’ve pursued to stay current with today’s market, and how they use that knowledge to benefit their clients.

Without an interview, how can buyers and sellers know what level of service to expect?

Q&A: Insights from Industry Discussion

Q: How do you get clients to care about sustainability and energy efficiency? Are you seeing higher listing or sales prices?

A: Energy efficiency and sustainability are introduced at the very first meeting with buyers and sellers, with emphasis on health, utility savings, and long-term value. Documented features and clear explanations often lead to increased interest and, in some cases, higher appraisals.

Q: What advice do you have for home inspectors or energy auditors seeking to collaborate with realtors?

A: Real estate agents should encourage home inspectors to study building science and earn energy-auditor credentials. These qualifications can benefit inspectors, agents, and clients, while a bundled inspection and energy-audit service adds value for homebuyers and advances the industry. Although offering this additional service may increase inspectors’ liability, more detailed information about a home’s performance could also help reduce it.

Q: Does solar ever hurt a home’s value?

A: Leased and 3rd party financed solar panels DO NOT add value, and both can complicate transactions.  Owned systems, properly documented, can increase appraisal value using tools like PVValue.com.

Q: How should green features be documented for appraisers?

A: Provide detailed, itemized lists of all upgrades, dates of installation, costs, and supporting documents such as utility bills and certifications. Upload these to the MLS and present them directly to appraisers.

Q: What is the role of artificial intelligence (AI) in green real estate?

A: Ai is a useful tool to help define public remarks, especially when it comes to energy efficient features.  Our limit for public remarks in Arizona is 800 characters.  Ai can help concisely describe features, but make sure you aren’t abusing greenwashing by misrepresenting the features.  My advice to agents is to have a seller explain each feature so you understand it and can share that knowledge.”

Key Takeaways

  • Green realtors bring specialized knowledge to the marketing, valuation, and sale of high-performance homes.
  • Accurate documentation and transparent communication of green features are essential for realizing value in real estate transactions.
  • Energy audits and phased improvements provide the best return on investment for homeowners.
  • Appraising green homes requires collaboration, qualified appraisers, and detailed supporting materials.
  • Leased or financed solar systems do not contribute to home value; owned systems, properly documented, can.
  • Ongoing education and industry engagement are critical for advancing sustainability in real estate.
  • Artificial intelligence can support but does not replace the need for professional expertise in green real estate.
  • The role of the green realtor is increasingly important as demand for sustainable housing grows.
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ClearlyEnergy Partnership to Make Home Energy Score Easier

This year, we are celebrating our 10-year anniversary of running the US DOE Home Energy Score program.

Over that time, our trained assessors have overseen 2,000 scored homes!



Now we are thrilled to announce a collaboration ClearlyEnergy to support our Home Energy Score (HES) assessment and training workflows using the Remotely application.

The Remotely tool is a smartphone-based virtual home energy assessment application designed to overcome the limitations of traditional home energy assessments, high costs, time-consuming processes, and a limited assessor workforce. As the application has evolved, it has become a holistic home energy tool that guides homeowners, contractors, home inspectors, realtors, appraisers, assessors, and program implementers through the entire home energy retrofit process.

Remotely, a Department of Energy (DOE) certified Home Energy Score software solution guides users through the full DOE HES assessment with innovative features like augmented reality measurements of windows and floor area, built-in tutorial videos, photo capture, and offline data collection, helping assessors and trainees collect complete, accurate data in less time.

Please visit our DOE Home Energy Score training page to submit and begin your virtual, remote Home Energy Score training on your schedule.


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What Happens to the Old Appliances When a Home Goes All-Electric

Article by Eric Hinderager – Top Shelf Junk Removal

Going all-electric usually gets talked about in terms of what’s coming into the house. A heat pump. A heat pump water heater. An induction range, maybe a new fridge while you’re at it.

Much less gets said about what’s going out. The gas furnace, the old tank water heater, the range, the second refrigerator humming away in the garage. None of that disappears when the installer packs up, and how it’s handled is part of the project’s environmental footprint, just like the efficiency rating on the new equipment.

Why Old Appliances Deserve a Plan

Major appliances are mostly metal: steel cabinets, copper lines, aluminum, motors and compressors. That makes them some of the most recyclable things in a house, but only if they actually reach a recycler instead of a landfill.

Cooling appliances bring an extra concern. Refrigerators, freezers, window units and central air conditioners all hold refrigerant, and older equipment often uses gases with a high global warming potential. The insulation foam inside older refrigerator and freezer cabinets was also made with blowing agents that EPA has since moved the industry away from. Crush that cabinet without capturing what’s inside and those gases go straight into the air.

So the question isn’t just whether the old furnace gets hauled away. It’s where it goes, and whether anyone along the way is handling the refrigerant and recoverable material properly.

What the Rules Actually Require

EPA’s Section 608 rules spell out who is responsible. For appliances that enter the waste stream with their charge intact, like household refrigerators, freezers and window AC units, the final person in the disposal chain, usually a scrap recycler or landfill, has to make sure the refrigerant is recovered before final disposal. Equipment that’s dismantled on site, such as a central residential air conditioner, needs its refrigerant recovered before disposal under the same requirements technicians follow during servicing.

For homeowners, the practical version is simple. When a heat pump replaces a central AC system, ask the installer how they’re handling the old refrigerant. And when an old fridge or freezer leaves the house, know where it’s headed.

Reuse Comes Before Recycling

Not everything that comes out of an electrification project is junk. A working gas range or a fairly new refrigerator can have years of life left in someone else’s kitchen.

Habitat for Humanity ReStores accept many appliances, cabinets and building materials and resell them to help fund housing. What each store takes varies, so it’s worth calling yours before you load anything up.

That order of operations matches how EPA approaches construction and demolition materials in general: reduce and reuse first, then recycle what’s left. A reused appliance also spares the next owner the embodied carbon of manufacturing a brand-new one.

Working Removal Into the Project Schedule

Disposal goes a lot smoother when it’s planned up front instead of left for the last day. A few things that help:

  • List everything being replaced before work starts, and sort it into reuse, recycle and scrap.
  • Have gas appliances disconnected and capped by a licensed professional before anyone moves them.
  • Confirm in writing whether your installer takes the old equipment. Some include the old furnace or water heater in the job, but rarely the fridge, washer or range you swapped out at the same time.
  • Keep anything still holding refrigerant upright and intact until it’s picked up.

For whatever’s left, find a hauler who recycles and can tell you where each item ends up. That’s the whole idea behind hauling off old appliances for recycling around Boise. The heavy lifting is the easy part. The useful question is where each piece ends up once it leaves the driveway.

Counting the Exit, Not Just the Entrance

Green building programs ask a lot of questions about what goes into a home, from material sources to the efficiency of a new heat pump water heater. The equipment coming out deserves the same attention.

A retrofit that cuts a home’s energy use but sends a load of refrigerant, foam and scrap metal to the landfill hasn’t finished the job. Plan the exit as carefully as the install, and the whole project lines up with the reasons you started it.

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Ventilation without renovation – Window ERVs

Austin Riesenberger joined us recently on our weekly free CEU webinar series to talk about Ventilation Without Renovation: Solving High CO2 and Poor Air Exchange in Existing Homes.

Review a summary of attendee feedback below, watch the recording, and/or read an article on the topic below.

Webinar attendees learned extensively about indoor air quality and the importance of proper ventilation in homes. Many were surprised to discover how high CO2 and VOC (volatile organic compound) levels can become in bedrooms, especially at night, and how indoor air can be significantly worse than outdoor air. The session highlighted that code requirements for ventilation can vary by jurisdiction and emphasized the value of actively monitoring indoor air quality using available sensors. Attendees also learned that typical store-bought air purifiers may not be effective against VOCs and that balanced ventilation, such as that provided by ERVs (Energy Recovery Ventilators), is crucial for healthy indoor environments.

Ventilation remains a critical but often overlooked aspect of residential building health and sustainability. As energy codes tighten and buildings become more airtight, achieving optimal indoor air quality in both new and existing homes becomes increasingly challenging. This article explores the evolution of residential ventilation, with a focus on affordable, scalable solutions for existing buildings—particularly the emergence of window-based energy recovery ventilators (ERVs) and smart ventilation technologies. Drawing exclusively from expert discussion and industry experience, the article provides a comprehensive, educational overview suitable for housing professionals and an interested general audience. Key considerations include technical standards, device comparisons, installation challenges, energy and health trade-offs, and the future direction of residential air quality management. A dedicated Q&A section addresses common concerns regarding maintenance, monitoring, filtration, and practical deployment.

Ventilation in the Modern Home: Challenges, Solutions, and the Future of Indoor Air Quality

The importance of ventilation in residential buildings has grown substantially as codes, green certification programs, and occupant health priorities have evolved. Today, ventilation is not only a code requirement in many jurisdictions but is also central to programs such as LEED, Green Star, and others that incentivize better air quality and energy performance. However, the reality for much of the housing stock—especially existing homes—is that effective, efficient ventilation remains a significant challenge. This article examines the underlying science and technology of residential ventilation, the barriers homeowners and housing agencies face, and the innovations that are reshaping what is possible for both professionals and the public.

The Ventilation Pyramid: From Baseline to Best Practice

A useful conceptual model for understanding residential ventilation is the “Ventilation Pyramid,” which mirrors the approach used in home energy efficiency. At its base are local code requirements, which increasingly include minimum ventilation standards. These are often derived from ASHRAE standards, specifically the 62.2 series, which has evolved over the years to define minimum rates for fresh air exchange in residential settings. Depending on region, these requirements may be triggered by state energy rebates or weatherization programs, and are now extending into renovations, not just new constructions.

Above code minimums are the requirements of green building programs, such as LEED for Homes and similar certifications. These typically mandate devices that either continuously or intermittently bring in fresh air or exhaust stale air—most often via bath fans, furnace intakes, or similar systems. While these approaches fulfill foundational standards, they are not always optimized for occupant health, nor do they always consider energy efficiency holistically.

The next tier in the pyramid is “balanced ventilation,” which involves systems that bring in and exhaust air in equal measures. Balanced systems are widely regarded as best for health and comfort, as they offer consistent, controlled air exchange. Verification and testing are critical at this level to ensure that systems are indeed delivering the intended rates of air change. However, balanced ventilation—especially when verified—can be energy-intensive, as the process of exchanging indoor and outdoor air often results in substantial heat loss.

At the pyramid’s apex are energy recovery ventilators (ERVs) and smart ventilation systems. ERVs reclaim thermal energy from outgoing air, using it to temper incoming air, thereby reducing the energy penalty of ventilation. Smart ventilation systems go a step further, using sensors to activate ventilation only when indoor pollutant levels (such as CO2, VOCs, or particulates) exceed healthy thresholds. This approach aligns ventilation rates with real-time need, maximizing both air quality and energy efficiency.

Why Ventilation Matters: Beyond Compliance

While meeting code and certification requirements is essential, the true value of effective ventilation lies in its impact on human health and cognitive function. Elevated indoor CO2 levels have been directly linked to poor sleep, headaches, brain fog, and reduced productivity. In tightly sealed homes, CO2 and other indoor pollutants can quickly accumulate to levels well above outdoor baselines, particularly in bedrooms and other spaces with limited natural air exchange.

Volatile organic compounds (VOCs), radon, particulate matter, and moisture are also common indoor contaminants. While air purifiers can address some particulates and odors, they do not remove CO2 or radon and are not substitutes for actual air exchange. In older homes, natural infiltration once provided a degree of ventilation, but modern weatherization practices have reduced this effect, making mechanical ventilation more critical than ever.

Current Solutions: Windows, Fans, and ERVs

The simplest form of ventilation remains opening windows, which is effective but highly dependent on outdoor conditions. High humidity, extreme temperatures, pollution, allergens, and noise are all factors that can make window ventilation impractical for much of the year. Bath fans and furnace intakes provide a mechanical solution, but these are often “supply only” or “exhaust only,” meaning they can create pressure imbalances and are not always energy efficient.

Central ERV systems are the gold standard in new construction, providing balanced, energy-recovering ventilation throughout the home. However, retrofitting these systems into existing buildings is typically expensive and invasive, requiring ductwork, wall penetrations, and skilled labor. For renters, housing agencies, or owners of smaller homes and apartments, these solutions are often out of reach.

Emerging Technologies: Window ERVs and Smart Ventilation

Recent advances have led to the development of window-based ERVs—compact, ductless devices that can be installed much like a window air conditioner. These units combine the core benefits of ERVs (energy recovery, balanced exchange) with the accessibility and affordability needed for existing residences. They are especially valuable for applications where traditional ducted ERVs are impractical, such as in rental units or older buildings without easy access for renovation.

Window ERVs use heat exchanger cores to transfer thermal energy between outgoing and incoming air streams, minimizing heat loss or gain depending on the season. Some models employ a “regenerator” type core, which can offer higher efficiency in a smaller package. These devices may operate in different modes, including continuous, dual (simultaneous supply and exhaust), and smart modes that adjust operation based on real-time air quality measurements.

Smart ventilation, increasingly integrated into modern devices, uses sensors to monitor CO2, temperature, humidity, and sometimes particulates. These systems can throttle ventilation up or down as needed, preventing both under- and over-ventilation. Automated controls, combined with user override options, allow for both energy savings and occupant empowerment—a critical requirement under many green building standards.

Technical Considerations: Installation, Filtration, and Controls

Installation of window ERVs typically involves a foam block and bracket system to ensure a tight, insulated fit within a variety of window types—most commonly double-hung or sliding windows. While some customization is possible, compatibility with casement windows remains a limitation for many devices on the market. Security concerns are addressed through the use of window locks and careful installation to prevent tampering or forced entry, especially on ground floors.

Filtration is another key aspect of modern ventilation devices. MERV 13 filters with embedded activated carbon are increasingly standard, providing protection against particulate pollution, smoke, and odors. Maintenance requirements are minimal, usually limited to filter replacement every six months and occasional cleaning of pre-filters or cores. Some devices include washable components, though care must be taken not to damage sensitive coatings or electronics.

Controls on smart ERVs often include manual settings, auto modes, and the ability to integrate with mobile apps for data tracking and remote management. Some systems can connect to local weather and air quality APIs, providing additional context for operation. Importantly, user control is mandated by many building standards, ensuring occupants can override automated operation as needed.

Performance and Validation: Measuring Success

Verification of ventilation system performance is a critical step in both compliance and real-world efficacy. In the field, airflow can be measured using anemometers and hoods to confirm that devices are delivering the design-specified cubic feet per minute (CFM). However, real-world factors such as stack effect, wind, and building pressure differences can impact performance, making ongoing monitoring valuable.

Increasingly, experts argue for a shift from one-time airflow testing to continuous air quality monitoring—using CO2 levels as a direct proxy for effective ventilation. This approach recognizes that prescribed CFM rates may under- or overestimate actual needs due to occupancy patterns, building characteristics, and environmental conditions. Alerts and notifications can be integrated into smart systems to inform users if air quality falls outside acceptable ranges.

Cost and Accessibility: Making Ventilation Work for All

One of the most significant barriers to improved residential ventilation is cost—both for equipment and installation. Central ERVs and ducted systems can easily run into thousands of dollars, with installation often costing more than the device itself. Wall-mounted ERVs, while less expensive, still require specialized tools and expertise. In contrast, window ERVs offer a dramatically lower installed cost. Most can be installed by a homeowner or with minimal professional assistance, with contractors typically charging $200–$500 per unit for installation if needed. This accessibility opens the door for widespread adoption in both single-family and multifamily settings, including rentals and affordable housing.

The Role of User Experience and Future Directions

As residential ventilation technology matures, user experience is coming to the forefront. Occupants must be able to control, monitor, and maintain their systems easily. Devices that are difficult to access, require specialized knowledge, or limit user intervention risk non-compliance and poor long-term outcomes. Modern ERVs address this by providing accessible controls, modular components, and clear maintenance instructions.

Looking ahead, further integration of predictive controls and AI-driven optimization is likely. However, user override and manual control will remain essential, both for compliance and occupant trust. Additionally, the field is moving toward “permanent commissioning,” where continuous monitoring and alerting ensure that ventilation remains effective throughout a building’s lifecycle.

Question and Answer Discussion

Q: Can window ERVs be installed in homes with casement windows or other non-standard window types? A: Most current window ERV models are designed for double-hung or sliding windows. Compatibility with casement windows is limited, though future models and adapters may expand options. For now, custom installation is possible but not generally recommended unless undertaken by a skilled professional.

Q: What is the best location in a home for installing a window ERV? A: The ideal placement is in the room where the occupant spends the most time and where air quality is poorest—typically bedrooms or home offices. Bathrooms and kitchens, while important for moisture and odor control, are not prime candidates for these devices.

Q: Are window ERVs compatible with horizontal sliding windows? A: Yes, most modern window ERVs are fully compatible with horizontal sliding windows as well as vertically sliding double-hung and single-hung windows.

Q: How is security addressed when installing a window ERV? A: Security can be maintained using specialized window locks that prevent the window from opening further once the ERV is installed. These locks are available for different window types and can be matched to the installation for added safety.

Q: What are the filtration options, and how often should filters be replaced? A: Most window ERVs use a MERV 13 filter with activated carbon, replaced approximately every six months. Pre-filters may be washed or vacuumed as needed. Running the unit without a filter is not recommended, as it increases dust accumulation and noise.

Q: Can third-party air quality sensors be integrated with window ERVs? A: Currently, most devices do not support direct integration with third-party sensors. However, standalone sensors (such as AirThings View Plus or Air Gradient 1) can be used for independent monitoring. Future models may offer more integrated solutions.

Q: What are the sensible and latent heat recovery efficiencies of window ERVs? A: Sensible heat recovery is typically around 85% at standard test conditions (32°F, 0°C), peaking at up to 90% at optimal fan speeds. Latent recovery (moisture transfer) is slightly lower, generally between 80–83%. Higher fan speeds reduce efficiency.

Q: How do window ERVs handle wind-driven rain or condensation? A: Devices are designed with a slight tilt and drainage channels to direct water away from the interior. Field testing in various climates has not revealed significant issues with ingress, but ongoing monitoring continues as more units are deployed.

Q: What is the ongoing maintenance required? A: Maintenance is minimal: filters are replaced every six months, pre-filters may be washed, and the core may be wiped down if needed. Full washing or hosing of the core is not recommended as it may damage sensitive parts.

Q: What are typical installation costs for window ERVs? A: Professional installation ranges from $200–$500 per unit, though most homeowners can install the devices themselves. The process is generally easier than installing a window air conditioner.

Q: I have an older home but upgraded with casement windows that rotate outward. Can you make a unit for a bedroom that can be mounted to a wall using a customized sheet metal housing to fit the mechanism of your window device?
A: Unfortunately, the SWERV is not currently compatible with casement windows. It is only designed for sliding windows that are at least 23″ wide.

Q: My SWERV just arrived yesterday! Would you recommend I install it in my office or my bedroom?
A: The bedroom is a great option, but a home office is also a good choice—anywhere you spend the most time and want better air quality.

Q: I’m concerned about security if the ERV unit is installed in a first-floor window, as the window would no longer be lockable. Is there a way to secure the window after the ERV is installed?
A: Yes, retrofit window locks are available at hardware stores or online. Different types of locks work better with different window types, so make sure they are compatible. We also offer window locks on our site as an option at checkout.

Q: Which CO2 monitors do you recommend?
A: We recommend the Airthings View Plus for its high reliability, clean app user interface, and its ability to measure CO2, temperature, humidity, pressure, particulate matter, radon, and VOCs.

Q: What is the sensible heat recovery at standard test temperatures of 32°F (0°C) at different CFMs?
A: Sensible heat recovery is around 85–90%, depending on fan speed. Lower fan speeds have higher efficiency (about 90–94%), while higher fan speeds (e.g., 120 CFM) can go down to about 75%.

Q: Is there a rule of thumb for the number of window ERV units required based on apartment square footage? For example, is one unit sufficient for a 900 sq. ft. living space with 9′ ceilings? If only one, should it be placed in a central window?
A: You should run a 62.2 calculation to determine the exact requirement. If you have blower door test data, that helps, but generally, two units are recommended. Each unit can serve one room up to 1,000 sq. ft.

Q: Is there a risk of wind-driven rain ingress when a window has a window ERV, AC, or heat pump installed?
A: Window ERVs and heat pumps tend to seal much better than window ACs, as they are designed for year-round use, including winter. They provide better protection against sideways rain, and we haven’t had issues with rain intrusion, though it is possible.

Q: What is the price point for these units?
A: The price starts at $799. Two extra filters are $49, and sensors that measure temperature, humidity, and CO2 (both inside and outside) for autonomous operation and app dashboard are $99.

Q: Is the ERV core washable?
A: The cores do not need cleaning if you keep the filters installed, but you can blow or wipe them off if needed.

Q: What size options are available?
A: Currently, there is only one size available, but we plan to offer multiple sizes in the future.

Q: Can you have custom sizes made?
A: Not at this time. However, the foam blocks are cut to size for any sliding window at least 23″ wide, and airflow is adjustable from 10–120 CFM.

Key Takeaways

  • Ventilation is essential for both health and energy efficiency in residential buildings, especially as airtightness increases.
  • Existing homes face unique challenges in achieving effective ventilation due to cost, complexity, and building constraints.
  • Window ERVs provide a practical, affordable solution for balanced, energy-recovering ventilation in a range of settings.
  • Smart ventilation technologies enable demand-controlled operation, optimizing air quality and energy use.
  • Installation and maintenance are accessible to most homeowners, with minimal ongoing costs and user-friendly design.
  • Verification of performance is shifting from one-time tests to continuous monitoring of air quality metrics, especially CO2.
  • User control remains critical, with manual override and accessible controls required by many building standards.
  • The future of residential ventilation will integrate predictive controls, ongoing commissioning, and a broader range of compatible devices.

 

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How Do Whole-Home Water Filtration Systems Work?

Article by Jane Marsh – environment co

Stained fixtures, an odd taste from the tap and a faint chemical smell after showering are all subtle clues of a larger water quality issue. A whole-home water filtration system offers a comprehensive solution by treating water at its point of entry. Long’s Eco Water, a company serving Eastern Pennsylvania since 1949, provides insights into the mechanics of this technology.

How Whole-Home Water Filtration Systems Treat Incoming Water

Point-of-entry systems are installed directly at the main water line, where municipal or well water enters a home. This positioning ensures that treated water flows to every outlet, from kitchen faucets to bathroom showers and laundry appliances, eliminating the need for individual fixture-level filters.

 

Multiple treatment stages work in sequence, with early phases removing larger sediment particles while later stages target taste, odor and chemical issues. According to Long’s Eco Water, properly designed systems can “eliminate these common issues, leaving homeowners with healthy, good-tasting water straight from the tap.”

The Hidden Contaminants Targeted by These Systems

Whole-home water filtration technology typically addresses several pollutant categories, including the following:

 

  • Sediment and particulates: Capture visible debris that causes cloudiness or buildup in pipes.
  • Chlorine and chloramines: Remove the disinfectants municipalities add that create taste or odor problems.
  • Heavy metals: Filter out substances like lead that leach from aging infrastructure.
  • Emerging pollutants: Focus on newer issues, including per- and polyfluoroalkyl substances (PFAS), which are found in trace amounts.

 

Two of these categories face particularly stringent federal oversight due to documented health risks. The Environmental Protection Agency (EPA) established new national drinking water limits in 2024 that specifically target six PFAS, marking the first legally enforceable standards for these compounds.

 

The federal thresholds for two specific PFAS, PFOA and PFOS, are set at extremely low allowable levels of 4.0 nanograms per liter — or parts per trillion — reflecting the seriousness of these emerging contaminants. Similarly, lead remains closely regulated decades after initial EPA monitoring began.

 

The Lead and Copper Rule requires utilities to take corrective action when levels exceed 15 parts per billion in more than 10% of tested samples, while whole-home filters generally handle problems affecting multiple outlets simultaneously. As Long’s Eco Water notes, “point-of-entry systems excel at addressing problems like hard water or chlorine that affect multiple fixtures” throughout a property.

Certifications That Separate Fact From Marketing

Third-party certification tests claims about filtration performance rather than relying on manufacturers’ self-reporting. This verification process helps homeowners and professionals build confidence that a product delivers on its promises rather than simply accepting marketing language at face value.

 

Among these testing organizations, Long’s Eco Water points to NSF International as particularly significant. The company explains, “NSF certification is a leading standard for water filtration systems,” with NSF International serving as the “independent body that tests and certifies products” against public health requirements.

 

NSF International administers these three primary benchmarks that provide the framework for evaluating filtration capabilities:

 

  • NSF/ANSI 42: Addresses aesthetic problems like chlorine taste, odor and general water clarity without targeting health threats.
  • NSF/ANSI 53: Addresses health-related pollutants such as lead and certain organic compounds that pose documented risks.
  • NSF/ANSI 401: Addresses emerging pollutants found in trace amounts, including some pharmaceuticals and industrial compounds.

 

When selecting a system, homeowners benefit from starting with a water test to identify which specific contaminants are present. The results then guide the search toward systems with certifications that match the pollutants in question.

Frequently Asked Questions

These common questions reinforce the core concepts behind whole-home treatment technology and performance verification.

What does whole-home water filtration actually do?

Filters installed at the main water line treat incoming water before it reaches individual outlets throughout a home. This whole-house approach resolves quality problems at the source instead of addressing isolated fixtures one at a time, which would require separate filters at each location. Multiple treatment stages operate in sequence to first remove sediment, then address taste and odor issues.

Why does certification matter when choosing a system?

Benchmarks such as NSF/ANSI requirements provide independent verification of performance claims, helping buyers identify systems tested for their specific water quality issues. NSF International administers three distinct certification levels that address aesthetic concerns, health-related pollutants and emerging compounds.

Can these systems address contaminants like lead and PFAS?

Lead and PFAS pose significant health risks in drinking water. Both contaminants are subject to strict federal regulation, with specific thresholds that utilities must meet. The EPA established a 4.0 nanogram-per-liter limit for PFAS in 2024, while the Lead and Copper Rule sets a 15 parts-per-billion threshold for lead. Whole-home systems handle these pollutants at the point of entry, ensuring treatment reaches every outlet simultaneously.

 

GreenStar Homes Gold Water Filtration 

 

GreenStar Homes Certification is one of the first green certifications to require higher water-quality standards. Check out the requirements for this at the Gold and Platinum level. 

The Bigger Picture for Whole-Home Water Quality

Grasping how whole-home water filtration works through staged treatment and certification verification builds confidence in making an informed decision. Point-of-entry technology handles multiple contaminant categories simultaneously, from sediment and chlorine to federally regulated substances like lead and PFAS. As treatment technology advances alongside evolving regulatory requirements, these systems remain integral to sustainable building practices prioritizing both water quality and long-term health.





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Making a 1980s ME home resistant to high power bills and power outages

We recently interviewed JB on our free weekly CEU webinar series about his home and what he did; below, you’ll find the attendee survey summary, recording, and an article from the discussion to learn what he did and how you can, too.

During the webinar, attendees learned about the many options available for home energy resilience, including the integration of solar panels, battery storage, and backup generators such as those from Generac. Many were surprised to discover that Generac is not only a generator manufacturer but also offers battery storage solutions that can recharge from generators, integrate with solar, and provide smart load management during outages. The discussion also covered the complexities of managing energy flows—like load shifting and shedding, source cycling between batteries and generators, and the importance of smart controls for optimizing home energy use. Attendees appreciated real-world examples of site-specific power generation and the evolution of home energy systems, including the critical role of insulation and the need for consulting with professionals during upgrades or remodeling.

Participants also gained insight into broader issues such as the increasing frequency of power outages, the incentive structures influenced by state and local regulations, and the challenges of making homes more resilient, especially for vulnerable populations. The value of technological advancements—like AI-driven home management, virtual power plants (VPP), and smart circuit management—was also highlighted. Attendees noted the importance of considering both immediate and long-term benefits of energy upgrades, with many emphasizing that investing in insulation should be a top priority. Overall, the webinar emphasized a holistic approach to energy resilience, combining technical knowledge with practical, incremental steps toward greater sustainability and reliability.

This article explores the comprehensive retrofit of a 1980s home in Maine, detailing the transformation from a conventional residence into a resilient, electrified, and energy-efficient dwelling capable of weathering grid outages and adapting to modern energy demands. Drawing exclusively from lived experience and project details provided by the presenter, the article delivers actionable insights for housing professionals, builders, contractors, and the general public, blending technical depth with accessible explanations. The journey covers solar upgrades, battery integration, heat pump adoption, insulation improvements, smart controls, and the evolving role of generators, all in the context of real-world challenges and solutions.

From Vintage to Visionary: Transforming an 80s Home for Energy Resilience and Electrification

The transformation of existing housing stock into high-performance, resilient, and electrified homes is a central challenge and opportunity for the construction and housing industries. This article presents an in-depth case study of a 1980s home in southern Maine—a region known for its harsh winters, power outages, and evolving building codes—showcasing a stepwise retrofit that addresses decarbonization, energy efficiency, and grid resiliency. The technical narrative is grounded in real project experience, offering lessons and considerations for professionals and homeowners navigating similar journeys.

Site and Orientation: Harnessing Passive Solar Principles

The journey began not with new construction, but with the purchase of a “used” home—a term that carries its own quirks in the real estate world. The 1980s-era house, though relatively new by local standards, benefitted from an instinctively good orientation: a south-facing sunroom designed for winter solar gain and summer shading, thanks to thoughtful roof overhangs. This passive solar strategy, achieved more by intuition than by reference to modern standards at the time, created a foundation for ongoing efficiency improvements. The sunroom’s dramatic seasonal light shifts provided not only comfort but also set the stage for integrating active solar technologies.

Early Solar Adoption and Challenges with Solar Thermal

Early on, the drive to decarbonize led to the installation of a solar thermal system—a technology more common in past decades, but now less familiar to many practitioners. The system utilized 40 evacuated glass tubes and a recirculating antifreeze loop to supply domestic hot water. While initially a source of pride, the solar thermal system presented challenges: maintenance of the vacuum tubes, fluid management, and eventual system “boil-over” during a roof replacement. Ultimately, the solar thermal system was decommissioned and donated to a local program, illustrating both the promise and complexity of legacy solar thermal technology.

The Move to Photovoltaics: Two Generations of Solar PV

Photovoltaics emerged as the next logical step. The initial PV installation featured 24 panels with modest wattage by today’s standards, paired with an Enphase system. This first phase of PV provided reliable, if limited, self-generation. With advances in panel and inverter technology, a subsequent upgrade replaced the original panels with higher-wattage units and integrated modern microinverters with advanced monitoring and optimization. This not only increased total system output but also improved resilience and diagnostic capability—crucial for both homeowners and service providers in remote or outage-prone areas.

Battery Storage: Enabling True Resilience

The integration of battery storage marked a pivotal shift in the home’s energy profile. An 18 kWh stationary battery system was installed in the basement, compliant with local code and without the need for special enclosures. This stationary storage, paired with the PV system, enabled the house to maintain core services during grid outages, a necessity for homes located at the end of rural feeder lines. Additionally, the presence of an electric vehicle (EV) with its own substantial battery capacity hinted at the future convergence of stationary and mobile storage, though vehicle-to-grid technology was not yet implemented in this case.

Electrification of Heating and Cooling

A critical element in the decarbonization process was the electrification of space conditioning. The original forced hot air oil furnace—noisy, dusty, and increasingly inefficient—was replaced with mini-split heat pumps. These systems, common in New England’s “heat pump mania,” offer both heating and cooling with greater efficiency and less maintenance. The addition of a radiant electric floor in the sunroom further improved thermal comfort. Over time, the complete removal of the oil furnace freed up valuable basement space and improved indoor air quality, while a wood stove and a backup gas heater provided additional redundancy for extreme weather events.

Water Heating: Transitioning to Heat Pump Solutions

The transition away from solar thermal for water heating was supported by the adoption of a heat pump water heater. This system, installed in the basement, provided efficient hot water production and offered the ancillary benefit of dehumidifying the basement space. The hybrid operation of the heater ensured reliability during periods of high demand or limited solar input, further reducing reliance on fossil fuels.

Envelope Upgrades: Insulation and Air Sealing

Despite familiarity with the maxim, “before you spend a dime on solar, spend a dollar on insulation,” the insulation upgrade came later in the retrofit process. The attic’s aging fiberglass batts—contaminated and underperforming—were removed and replaced with 16 inches of blown-in cellulose. Spray foam was applied to the rim joists and exterior basement walls. Comprehensive air sealing was performed with contractor support, following best practices verified by blower door testing and third-party inspection via state efficiency programs. This upgrade stabilized indoor temperatures, reduced heating and cooling loads, and enhanced the performance of all subsequent investments.

Smart Controls, Load Management, and Optimization

A defining feature of the retrofit was the integration of smart controls and load management. Ecobee smart thermostats, installed with custom wiring to interface with mini-split systems, allowed precise zone control and remote management. Beyond simple scheduling, these thermostats enabled “load shifting” during outages—automatically adjusting temperature setpoints to maximize battery life while maintaining minimum comfort and safety thresholds. The addition of a dedicated power manager device provided granular control over major 240V loads (well pump, water heater, EV charger, clothes dryer) and permitted dynamic prioritization based on real-time conditions and user input. This system, combined with app-based monitoring, empowered both proactive and reactive energy management.

Resilience Testing and Outage Simulation

One of the most instructive aspects of the project was the willingness to rigorously test the home’s resilience. By simulating grid outages, the system demonstrated the ability to “yo-yo” between solar and battery storage for up to sixteen days, contingent on weather, insulation, and behavioral adjustments. Strategic use of thermal mass, pre-heating/cooling, and staged load reduction extended battery autonomy. Real-world challenges, such as snow accumulation on panels and evolving family occupancy, provided valuable feedback on system limitations and optimization opportunities.

The Role and Timing of Generators

While the primary goal was electrification and decarbonization, the realities of long-duration outages and winter conditions led to a nuanced view of backup generation. The home was designed to integrate seamlessly with a generator as a last-resort power source, programmed to activate only when battery reserves reached critical thresholds. The system’s intelligence allowed cycling between solar, battery, and generator based on resource availability and household needs, minimizing fossil fuel use while ensuring safety and continuity.

Economic and Regulatory Context: Incentives, Rates, and Program Participation

The retrofit leveraged state-level efficiency programs for both insulation and heat pump upgrades, as well as rebates for battery systems (where available). Participation in virtual power plant (VPP) programs, time-of-use (TOU) rates, and net energy billing was explored, though outcomes varied by utility territory and regulatory environment. The article emphasizes the importance of local context—code requirements, incentive structures, and utility policies—when planning similar projects.

Health, Comfort, and Indoor Air Quality

Beyond efficiency and resilience, the upgrades produced measurable improvements in comfort and health. The removal of contaminated insulation, improved air sealing, and the shift to electric heating reduced indoor pollutants and allergens. Smart sensors and monitoring provided real-time feedback on air quality and humidity, informing decisions about ventilation and system operation. The careful balance between airtightness and healthy ventilation was maintained through professional consultation and iterative testing.

Lessons Learned and Best Practices for Professionals

This comprehensive retrofit offers several core takeaways for housing professionals, builders, and contractors:

  • Begin with a holistic assessment of the building: orientation, envelope, and existing systems.
  • Prioritize envelope improvements (insulation, air sealing, passive solar gains) before investing in active systems.
  • Integrate electrification measures—heat pumps for space and water heating, induction cooking—while retaining redundancy for extreme events.
  • Size and phase PV and battery systems to match both current and projected loads, considering future EV integration and evolving family needs.
  • Employ smart controls and load management systems to maximize performance, resilience, and user engagement.
  • Rigorously test system operation under simulated outage conditions to validate design assumptions and user preparedness.
  • Stay current with local codes, incentive programs, and technological advances, adapting designs as the regulatory and product landscape evolves.
  • Approach projects consultatively, recognizing that every home and client will have unique priorities and constraints.

Questions & Answers: Expert Discussion

Q: How did utility savings play out as you transitioned through different phases of electrification and solar adoption? Did you benefit from special rates or programs?

A: Utility savings improved as each phase of the retrofit was completed, particularly after envelope upgrades and the addition of solar and battery storage. While net energy billing and virtual power plant (VPP) participation are valuable, outcomes depend on local utility offerings and regulatory frameworks. Time-of-use (TOU) rates in Maine, for example, provided less pronounced cost differentials than in some other states. The key lesson is to analyze utility programs carefully and integrate them into the retrofit plan where possible.

Q: What trade-offs were considered in removing old insulation versus adding new layers?

A: The decision to remove old fiberglass insulation was influenced by health considerations—contamination and potential air quality issues—outweighed the embodied carbon argument for leaving it in place. Removing the old batts allowed for proper air sealing and installation of high-performance cellulose, resulting in superior comfort and efficiency.

Q: How did the smart thermostat and load management systems perform in real-world outage scenarios?

A: Smart thermostats enabled automated temperature adjustments and prioritized battery life during outages. Integrated power managers provided granular control over large loads, allowing real-time user decisions based on available battery capacity and household priorities. The system also provided predictive feedback on remaining battery duration, helping occupants plan and adapt during extended outages.

Q: Are there special considerations for power quality and sensitive electronics with modern battery systems?

A: Yes. Battery inverters provide clean, conditioned sine wave power, often superior to long rural grid feeds. In practice, sensitive appliances and electronics operated more smoothly on battery power, with less noise and voltage fluctuation, as verified by direct measurement and data logging.

Q: Would you change the sequencing of retrofit measures if starting over?

A: Yes, earlier investment in insulation and air sealing would have yielded earlier and greater benefits. Each step built upon the last, but prioritizing the envelope would have improved the performance of all subsequent upgrades.

Q: Can these retrofit strategies be adapted for other regions or climates?

A: Absolutely, but local code, climate, utility structure, and occupant priorities must be factored into system design. Some technologies (e.g., battery placement, heat pump sizing) require adjustment based on regional conditions. Consultative planning is essential.

 

Q: What type of gas heater do you use—methane (natural gas) from a utility or propane from a tank?
A: I have a Rinnai propane direct vent heater on the main floor and a 120-gallon propane tank located outside.

Q: What was the cost of installing a hybrid water heater, and what was the length of the condensate line run?
A: My hybrid heat pump water heater was installed after I removed my solar domestic hot water system, so the plumbing and 240V electrical were already in place. At the time of purchase, Efficiency Maine offered a $750 point-of-sale instant rebate (now up to $1,200). My plumber is a neighbor, and I handled the removal of the old system myself, so I do not recall the exact net cost, but it was approximately $800 USD. For the condensate line, my laundry area is nearby, so we used a 120V Little Giant condensate pump to route condensate to the laundry drain. The installation was straightforward.

Q: How do you maintain power during grid shutdowns with a grid-tied system? Do you have a disconnect or transfer switch?
A: Yes, I have a transfer switch, specifically the Generac SDS. All grid-forming backup power solutions require a transfer switch.

Q: Is there an alternative to batteries for maintaining some backup power with grid-tied systems?
A: Enphase introduced a “sunlight backup” option without batteries in 2022 or 2023. Please check with Enphase directly to see if this option is still supported.

Q: Do you monitor voltage drops, especially given the sensitivity of modern electronics?
A: Yes. My PWRcell 2 system transfers over in milliseconds and provides a clean 60 Hz output. We monitored my house with a Fluke power quality recorder, which captured detailed data including THD (total harmonic distortion), voltage, and current.

Q: If you could redo your home electrification process, what sequencing would you recommend for maximum efficiency?
A: Insulation should come first for efficiency, although real-life projects do not always proceed in a linear order.

Q: Does having an on-premises Power Manager eliminate the monthly subscription required for a natural gas generator, especially if WiFi access is sufficient for the homeowner?
A: The PWRmanager manages loads during outages by shedding or prioritizing them; it is not a generator. I do not have a home standby generator, but those systems often carry a subscription fee for fleet monitoring. There are lease options available that include all costs, including the monthly fee.

Q: Have you tried staying off-grid for an entire year, and if so, how many days were you able to remain off-grid?
A: My solar system is grid-tied, allowing me to earn net energy billing credits with my utility. I am not aiming to be off-grid year-round; instead, I have tested grid outage scenarios as part of a product reliability trial. I have demonstrated backup power capability in all four seasons in New England but primarily rely on grid power.

Q: What is your experience with removing old attic insulation in an older house, particularly regarding indoor air quality (IAQ) and electrical safety?
A: Removing old attic insulation was critical. In addition to addressing IAQ concerns, I discovered and repaired mouse damage to electrical wiring, which was essential before any further work. Starting with a clean attic allowed me to inspect wiring and prepare the space for new insulation, which I strongly recommend for other retrofits.

Q: Regarding off-grid capability, have you tracked how many days per year you could remain off-grid (e.g., 16 days off, 2 days on-grid, etc.)?
A: I can back up my house year-round and have experienced both simulated and actual outages in all four seasons. However, I benefit from grid-tied net metering, which allows me to rely on backup power when needed, while primarily using utility power.

Key Takeaways

  • Passive solar design and orientation provide a durable foundation for efficiency.
  • Removing obsolete systems and electrifying heating, cooling, and water heating enhances comfort, air quality, and resilience.
  • Battery storage, when integrated with solar PV and intelligent controls, transforms homes into microgrids capable of weathering long outages.
  • Smart thermostats and power managers are critical for dynamic load management and user engagement.
  • Envelope upgrades, including insulation and air sealing, should precede or accompany electrification for optimal results.
  • Real-world outage simulation and iterative testing are vital for validating system performance.
  • Utility programs, codes, and incentives play a significant role in project economics and design.
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Uncategorized

Cohasset Habitat Home Tour: Low Carbon Building Solutions for Affordable Housing

Low-Carbon Building Solutions for Affordable Housing: Lessons from a Northern Minnesota Case Study

Below the article is the webinar recording, and the article is an article generated from the webinar

Abstract: This article explores innovative, replicable strategies for constructing affordable, sustainable housing in cold climates, as demonstrated by a recent Habitat for Humanity project in northern Minnesota. Drawing directly from the insights and experiences of the project team, the article examines the technical and practical aspects of designing high-performance homes that balance cost, efficiency, resilience, and occupant health. It provides a comprehensive overview of wall assembly innovations, HVAC simplification, embodied carbon reduction, and the challenges and opportunities for wider adoption. The article concludes with a focused Q&A discussion and a summary of key takeaways for housing professionals and the general public.

Introduction: The Challenge of Affordable, Sustainable Housing

The need for affordable housing is urgent, but so is the imperative to ensure that such housing is sustainable, resilient, and healthy for occupants. Traditionally, the pursuit of affordability has sometimes been seen as being at odds with sustainability goals, leading to a perceived trade-off between initial construction costs and long-term environmental and health outcomes. Recent advances, however, show that these priorities can be aligned through thoughtful design, innovative construction practices, and careful attention to both upfront and lifecycle costs.

A recent project in northern Minnesota provides a compelling example of how these challenges can be met. Built by a local Habitat for Humanity affiliate in partnership with the Youth Build program, this 1,292-square-foot, three-bedroom, two-bathroom home achieves exceptional performance metrics while remaining within the constraints of a nonprofit affordable housing model. The lessons learned from this project offer valuable guidance for housing professionals, policymakers, and anyone interested in advancing the field of sustainable, affordable housing.

Project Overview and Performance Metrics

Located in climate zone seven, the featured home exemplifies the integration of affordability and high performance. The building envelope boasts R20 subslab insulation, R44 walls, R70 attic insulation, and 0.17 U-value triple-pane windows. Airtightness testing yielded results between 0.7 and 1.25 ACH50—levels typically associated with passive house standards. The home’s Energy Rating Index (ERI) falls between 33 and 38, underscoring its exceptional energy efficiency.

The house is fully electric, relying on an all-in-one HVAC system that provides ventilation, heating, cooling, and dehumidification within a single unit. Additional features include a heat pump water heater and standard electric appliances. Notably, the project team was able to achieve these performance outcomes through careful material selection and advanced framing techniques, without incurring unsustainable cost premiums.

The Habitat for Humanity Model and Lifecycle Affordability

A critical element of the project’s success is the Habitat for Humanity model itself, which leverages partnerships, volunteer labor, and local expertise to control costs. Contrary to common misconceptions, Habitat does not give away homes but sells them at an affordable mortgage to families who would not otherwise qualify for conventional financing. The organization’s approach emphasizes not only low initial costs but also the minimization of operating expenses over the life of the home, including insurance, taxes, utilities, maintenance, and resilience against disasters.

Design decisions made at the outset—such as enhanced insulation, durable materials, and systems capable of adapting to changing climatic conditions—help ensure that families benefit from lower bills and more comfortable, safer homes over decades. Designing to meet or exceed anticipated future building codes further protects the long-term value and relevance of the homes.

Reimagining the Building Envelope: The Minnesota Wall

Central to the project’s approach is an innovative wall assembly dubbed the “Minnesota Wall.” This assembly uses a deep 2×10 framing bay, allowing for the use of cost-effective, “light and fluffy” insulation products that can be dense-packed or blown into place. By applying the continuous insulation layer to the interior of the wall rather than the exterior, the design simplifies both construction and air sealing, while minimizing the need for specialized materials or labor.

The use of 2×10 framing is particularly efficient in Minnesota, where the lumber supply chain is well-suited to producing this size. The assembly is further refined with a cross-strapping layer—providing what the team humorously refers to as “continuish” insulation—and careful notching of studs and headers to standardize and simplify construction.

This advanced framing approach yields several benefits:

  • Lower material costs by optimizing the use of standard, locally available products
  • Faster, more predictable assembly, which is especially valuable for volunteer-driven construction
  • Improved air sealing, as all electrical work occurs inside the thermal envelope
  • Enhanced resilience, as demonstrated by hygrothermal modeling (WUFI) that shows superior moisture management compared to code-minimum walls

Embodied Carbon and Lifecycle Emissions

Beyond operational energy, the project also sought to minimize embodied carbon—the greenhouse gas emissions associated with the manufacture, transport, and installation of building materials. By using off-the-shelf carbon-storing materials, low-carbon concrete with fly ash, and optimizing framing, the embodied emissions of the wall assembly were cut by more than half compared to conventional approaches.

A lifecycle assessment of the home’s emissions (over 25 years) reveals that as operational emissions are reduced through energy efficiency and electrification, embodied carbon becomes a larger share of the total footprint. In the case of this project, the embodied carbon of the building assembly could account for up to 80% of total emissions if HVAC is included. This underscores the importance of material choices and the potential for further reductions through design and procurement.

Simplified HVAC and Electrical Systems

One of the most significant advantages of high-performance envelopes is the ability to dramatically downsize heating and cooling systems. The project’s all-in-one HVAC unit replaces traditional, complex ducted systems with a streamlined, integrated approach. This not only reduces initial costs for equipment and installation but also cuts ongoing maintenance expenses and embodied carbon (through lower refrigerant volumes and less ductwork).

By minimizing the number of circuits required for major appliances and eliminating the need for outdoor condenser units, the electrical system is also simplified. This brings further cost savings and can ease the integration of rooftop solar and future resilience upgrades.

Resilience, Health, and Occupant Benefits

Resilience is a multifaceted consideration in home design, encompassing the ability to withstand climate extremes, maintain comfortable and safe conditions during power outages, and minimize disaster recovery costs. The Minnesota Wall’s high thermal inertia allows the home to retain heat for extended periods during winter outages, while large roof overhangs, carefully oriented windows, and passive solar design mitigate summer overheating.

Indoor air quality is also prioritized. The airtight envelope and filtered ventilation system protect residents from outdoor air hazards such as wildfire smoke, allergens, and smog—an increasingly important consideration in light of recent air quality events across North America.

Economic Analysis and Replicability

While the up-front cost of enhanced insulation and triple-pane windows added approximately $11,000 to the project, this was offset by savings from reduced HVAC complexity, fewer electrical circuits, and the elimination of many traditional construction steps. Available rebates for affordable housing construction can further tip the balance in favor of the high-performance approach, making it not only affordable but potentially less expensive than conventional alternatives.

Importantly, the construction process is designed to be accessible for volunteer labor, with standardized components and assemblies that reduce the need for specialized skills. This supports broader adoption among nonprofit builders, and the approach is already being replicated on additional projects in the region.

Challenges to Broader Adoption

Despite its many advantages, the approach is not universally applicable. Local availability of materials, volunteer training, climate conditions, and the capacity of the contractor workforce all influence which building systems are most appropriate. Electrification, for instance, is easiest in areas with favorable grid rates, solar access, and a skilled installer base. Water heating remains a particular challenge in some markets, especially where gas is cheap and electric resistance water heaters are costly to operate.

Existing buildings, especially masonry or historic structures, present further complexities. Deep energy retrofits are possible, but require careful planning to avoid moisture problems and may not always be cost-effective. Habitat for Humanity affiliates currently undertake relatively few full gut rehabs, focusing more on new construction and targeted home repair programs.

Q&A Discussion

Q: How important is third-party verification for these advanced building systems, and where should builders start? A: Third-party verification, such as that provided by HERS raters or Energy Star programs, is crucial for ensuring that high-performance features are properly installed and deliver the promised benefits. While funding sources may dictate specific requirements, starting with a HERS rating is often recommended, as it serves as a “measuring stick” for energy performance and provides a foundation for additional certifications.

Q: Why was continuous insulation applied to the interior rather than the exterior, and what are the labor and cost implications? A: The decision was driven by the desire to simplify installation, reduce costs, and make the process more accessible to volunteer labor. Applying insulation inside allows work to proceed in controlled conditions, accelerates the timeline for getting the building dried in, and leverages cost-effective materials. It also simplifies air sealing and reduces weather-related delays.

Q: How does the cost of the all-in-one HVAC system compare to other options? A: The all-in-one unit was marginally less expensive than separate ERV/dehumidifier systems with traditional ductwork, especially after accounting for reduced labor, fewer controls, and less ducting. In some markets, with applicable rebates, the overall approach could be less expensive than conventional code-minimum construction.

Q: Does the home’s solar system include battery storage, and how does this affect resilience? A: The project did not include battery storage, but the home’s high thermal inertia provides resilience during outages by maintaining safe indoor temperatures for extended periods. Advances in “plug-and-play” battery systems may offer additional options in the future, especially as technology and policy develop.

Q: What is being done to replicate this model, and what are the main barriers? A: There is significant interest in the Minnesota Wall approach, with additional homes planned in the local service area. The main challenges involve training volunteers and staff, adapting the model to different regional contexts, and overcoming inertia in established building practices. Mechanical system electrification is also spreading, but faces hurdles in areas without strong solar resources, off-peak electric rates, or a skilled installer base.

Q: Can these strategies be applied to existing homes or masonry retrofits? A: Deep energy retrofits are possible, but complex. The process is most feasible in homes already undergoing major renovations. For historic masonry buildings, additional challenges arise related to moisture management and preserving structural integrity. Habitat affiliates undertake a small number of acquisition-rehab projects, but the bulk of their work remains focused on new construction and owner-occupied repair programs, where efficiency upgrades are paired with health and safety improvements.

Key Takeaways

  • High-performance, low-carbon homes can be built affordably through advanced framing, efficient insulation, and simplified mechanical systems.
  • Lifecycle affordability depends not just on initial mortgage costs, but on minimizing utility, maintenance, and disaster recovery expenses.
  • The “Minnesota Wall” demonstrates that standard materials and volunteer-friendly assemblies can deliver both efficiency and resilience.
  • Embodied carbon is a growing share of total building emissions as operational energy use declines—material selection matters.
  • Simplified, integrated HVAC and electrical systems cut costs, reduce complexity, and improve reliability.
  • Resilience features—including thermal inertia, passive solar, and airtight construction—protect occupants from climate extremes and air quality events.
  • Third-party verification is essential for quality assurance and compliance with funding requirements.
  • Replication depends on local materials, contractor capacity, and climate—but the principles are widely applicable.
  • Deep energy retrofits for existing buildings are challenging, but targeted repairs and efficiency upgrades can deliver meaningful benefits.

This project stands as a replicable model for advancing both affordability and sustainability in housing, offering practical insights for builders, designers, and communities committed to healthier, more resilient homes.

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My experience: 10 years of ongoing sustainable & solar updates

When I bought my house in West Michigan in 2016, I saw it as a blank canvas—a chance to transform a typical early-2000s home into a model of modern sustainability. Over the last decade, I’ve tackled nearly every system and detail, driven by a desire for health, comfort, resilience, and climate action. Here is the full story of my sustainable upgrades, told in first person and with as much detail as possible. Below the article is a full virtual tour I lead. 
Getting Started: The Green Home Inspection (2016)
The very first step I took was commissioning a green home inspection, which included a DOE Home Energy Score, a blower door test (to assess air leakage), and a full review of water management, durability, and electrification potential. The home, built in 2002, performed slightly above code for its time, but had obvious deficiencies—especially in water management (no gutters, poor grading, problematic eaves) and some aging systems.
The inspection flagged missing carbon monoxide detectors, incandescent lighting, and recirculating kitchen ventilation that recirculated cooking pollutants. I also learned my HVAC was a 70% efficient gas furnace and an undersized, inefficient AC that struggled to cool the whole house. The water heater was an old natural-draft methane gas unit.
Immediate Fixes and Quick Wins (2016-2017)
My first actions were about safety and quick efficiency gains:
  • I installed low-level CO detectors.
  • I swapped every bulb for LEDs and installed 0.5 GPM aerators on bathroom faucets.
  • I upgraded my HVAC filter from MERV4 to MERV8 and set the furnace fan to run continuously for 24/7 filtration. I also ran the bath fan for continuous exhaust ventilation, getting about 80 CFM.
When my old top-loading washer failed in 2017, I replaced it with a front-loading Energy Star washer. I installed steel-braided hoses (90% less leak risk than rubber) and learned to keep the washer door open after use to prevent mold, plus started using the time-of-use setting to wash with cleaner/cheaper grid power.
First Big Upgrade: Heat Pump Water Heater (2018)
In 2018, my gas water heater started leaking. Instead of frustration, I saw opportunity. I replaced it with a 240V Rheem Prestige heat pump water heater, the highest efficiency model available. This unit features leak detection, remote control, and energy monitoring, and allowed me to lock it into heat pump mode only (no resistance backup). I used the app to track usage, set the temperature to 140°F off-peak and 120°F on-peak, and learned the importance of regular maintenance—flushing the tank and condensate line, and cleaning the filter.
While I didn’t save much in utility bills (electricity is expensive here, gas is artificially cheap), my motivation was to electrify, improve health, and showcase new tech. The upgrade bumped my DOE Home Energy Score from 7 to 8. I saw no measurable difference in humidity, low or high depending on the season, from the unit’s “dehumidification” feature, and the unit has been very quiet despite what people say about them.
Major Overhaul: Full Electrification & Ventilation (2020-2021)
By 2020, I was ready for a complete overhaul. I did extensive planning: manual J load calculations using my energy audit data, multiple HVAC system and solar quotes, and careful financial modeling. I weighed a high-efficiency gas furnace/AC, a dual-fuel heat pump, ground-source (geothermal), and air-source heat pumps. Geothermal would have required killing mature trees and came with a high upfront cost. Air-source (cold climate) offered nearly the same performance for much less, so I went all in: I removed the gas furnace and AC, installed a cold-climate air-source heat pump, and went 100% electric with no backup resistance for heating. With that being said, for many households in Michigan on most of the utility grids, the current electric utility rates could make winter heating very expensive; thus, until we can get electric utility rate reform, the best option is to attach a cold-climate heat pump outdoors, similar to an AC to an indoor high-efficiency gas furnace.
I also replaced old bath fans with Panasonic WhisperGreen Energy Star models (modulating up to 100 CFM), and installed a new range hood with smart controls tied to an air quality monitor—so it automatically ramps up if smoke or particulates (PM2.5) are detected. To ensure healthy indoor air, I added a Panasonic cold-climate ERV (energy recovery ventilator) after testing my air quality during a summer heatwave and seeing my CO2 rise excessively. The ERV is rated at 100 CFM of balanced, filtered fresh air through MERV 13, ducted into my existing HVAC system. I tested and calibrated all ventilation with RedCalc software, using data from my blower door test and aiming for ASHRAE 62.2 standards.
Solar and Battery (2021-2025)
Once I’d addressed energy efficiency and electrification as much as I could, in 2021I had Green Panel install 3.96 kW of Panasonic panels (south-facing garage) with Enphase microinverters for granular monitoring and reliability. Later in 2025, as it became clear the tax credit would expire sooner and I needed a new roof, I expanded by an additional 6.1 kW for a full 9.7 kW system, having Green Panel add panels to the east and west after a new roof and removing the now-unneeded chimney (thanks to electrification). In both cases, Green Panel accurately predicted the solar energy savings I got in both projects.
During my first solar project, in 2021, the goal was to go for the full system on the roof originally. Still, because of frequent power outages, the utility’s new time-of-use peak program, and trouble getting the financing I needed for a full solar project, I removed the east and west panels from the scope. I added a whole-home battery (13.5 kWh) instead to the project to protect against power outages since solar does not work when the grid is down, and to help me stay off-peak during summer days to save money, which solar usually does unless a cloud passes by or I need an extra midday afternoon boost of power load.
One thing of note is that in the 2025 solar update, I had just over 10 kW planned; the installers showed up to install it too and could not fit it, and we had to remove it from the cost and the house, and out of pure luck that worked out because the utility late in the game decided to try to charge me like $5,000 for a new utility pole transformer to handle the 10 kW load! So with the panel removed, I dropped below 10 kW.
Another major reason I added more solar later in 2025 was that, in 2021, right as my solar project wrapped up, one of my fossil gas cars broke down permanently. While I wanted to go all electric at that time, I could not find anything in my budget that would get enough winter miles, so I picked up a 2017 Volt, which is a PHEV, and so that added a major unexpected electrical load to my house, which sometimes, in the middle of winter at night especially, or while running many appliances and charging the car, I can reach loads of 12 kW; contrast that with the average home that is probably running less than 1 kW.  Thankfully, the home had a nice 200-amp panel, and the decommissioned hot tub freed up enough spaces for the level two car charger. But where the extra solar comes into play is that it is more cost-efficient to charge your home or vehicle with solar than to send it to your battery or the grid, and so now in the summer of 2025 I could fully charge my car in the middle of the day and power my house all the same time.
Water Conservation and Monitoring
Although I’m on a well (no direct water bill), I wanted to reduce aquifer drawdown and the water pump’s energy use. I replaced every toilet with a vacuum-assisted model: one single-flush at .8 gallons per flush and one dual-flush at .9 / .5 gallons per flush. These use less than half the current average flush rate of an existing home toilet, and toilets use the most water in a home. I replaced showerheads with 1.25 GPM units, and all appliances with Energy Star. I also installed a real-time water monitor with leak detection and temperature sensing. My Home Water Score improved from 1 (baseline) to 6 (Green Star Platinum level). My outdoor water use is effectively zero, as I don’t irrigate my Kentucky bluegrass or landscaped areas, and I shut down the automatic in-ground sprinkler system on the house had when I bought it; if another person owned this house, yard water usage would likely go up with more intentional watering. Over the last 5 years, I see our actual usage per year was roughly 53,000 gallons, compared to the average usage of 80,000 gallons for American households.
Air Quality, Radon, and Health
With COVID, wildfires, high CO2, and humidity issues, air quality became a science project for me. I got multiple air quality monitors tracking CO2, PM2.5, VOCs, humidity, radon, temp, pressure, and even mold risk, and tracked pre/post-upgrades. My first air quality monitor, added back in 2018, was so small I lost it, but it tracked and reported dew point, so I knew early on I had summer humidity issues in the basement and generally dry air in the winter, like most MI homes.  I also ran a cheap radon test when I bought the home, and it came back under the American action level of 4 but above the rest of the world and the WHO, which suggests action at 2.4. And it was in the 3’s. My radon monitoring system confirmed that levels spiked, especially in the wintertime as expected, at times above safe levels (despite being outside the EPA risk zone). So, as part of my project, I invested in major indoor air quality system upgrades as reviewed above. One of those systems was a radon mitigation system, and I was reminded that just because a system is installed doesn’t mean it works. Before I got my battery, a power outage knocked out the radon fan, and I would have never known if my air quality radon monitor hadn’t alerted me to levels exceeding the safe threshold!
Additionally, I upgraded to MERV16 filtration on my main HVAC and MERV13 on the ERV intake. I monitor humidity and mold risk with sensors in the basement and utility room; after seeing persistently high dew points, I added a whole-home dehumidifier (I should have done it as part of the main project, not as an add-on). It keeps the basement at 40-45% RH. According to the monitor, mold risk is now virtually zero, and I get automated alerts if anything spikes.
Noise, Comfort, and Other Upgrades
I measured noise before and after upgrades: my old gas furnace ran at nearly 59 dBA in the living room; the new heat pump, even at full speed, is under 35 dBA. The sound of my heat pump water heater hasn’t been that loud for being in a utility closet off the main living area. The dishwasher I got is also low dBA rated and is very quiet despite the open floor plan.  But the biggest issue was the range hood vent, which was installed rectangularly instead of round. This caused high static pressure, raising the dBA rating and sound levels above what the device is rated for, and it was very annoying when cooking. The HVAC came back and fixed it, and now it’s much quieter.
Another part of my roofing and solar project in 2025 included replacing two drafty entry doors with insulated fiberglass units, foaming and sealing the frame, and repairing some flooring. I immediately noticed the entryway was no longer too cold or warm, and it wasn’t as humid in the summer.  Since the entry is near the main living room, this helped the space stay cooler in the hot summer sun.
Lessons Learned and what I would like to do next
Looking back, I regret spending on motion sensor switches for all my lights because LED’s in general, use so little energy it didn’t matter. With the same amount of money I spent on that, I could have budgeted for a heat pump dryer (instead of condensing electric resistance, which uses a lot of energy and overheats the house in summer). In addition, during my first project I wish I had prioritized humidity reduction in my basement, perhaps spending funding on sealing a sump pump to prevent moisture and re-insulating and airsealing the exposed rim band joist in my crawlspace, which currently just has fiberglass batt shoved into it.
Looking ahead, dealing with crawlspace humidity and condensate while air sealing is my next priority; this should let me reduce dehumidifier use, significantly cut energy use, and extend its life.  Once that is taken care of, I could duct the dehumidifier into the ductwork to help maintain whole-home humidity and perhaps turn up the heat pump AC in the summer.
From there, I would like to switch my remaining gas vehicle to an all-electric car and then someday maybe insulate my house with two inches of rigid wood insulation and either add triple-pane windows or add interior storm windows to my current windows.
If the new electric car I get cannot do Vehicle-to-Home power, I’d like to consider another whole-home battery system to avoid sending so much power back to the grid in the summer and instead stay off the grid entirely throughout the summer.
Not including the dehumidifier at the outset was another oversight.
Financing
I funded all this through a blend of:
I worked with a lender willing to count the value of green upgrades in the appraisal, and Michigan law prohibits higher property taxes for these energy improvements, keeping my home mortgage payments down.
Results and Looking Ahead
My home is now GreenStar Homes Platinum Certified, DOE Home Energy Score 10/10, and Pearl Platinum certified. Home Water Score of 6 out of 10. Combined home and vehicle energy costs are a third of the US average, and my carbon footprint has plummeted. Every system is monitored, and I continue to share data, lessons, and updates on my blog and through the GreenHome Institute.
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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.

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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.

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