Home Indoor Air Quality Monitoring & DIY Automation joined us recently for our Weekly Wednesday Free CEU webinar Series.
If you missed this session, want to rewatch it, or share it with a friend or colleague, you can now do so, as the recording and article on the topic are available below. In addition, Scott answered some of the remaining Q&A below, and your question may have additional follow-up below.
Participants learned that the world of indoor air quality (IAQ) monitoring is far broader, more complex, and more inconsistent than they expected. Many were surprised by the sheer number of available sensors and brands (Awair, Airthings, PurpleAir, Omni, Fubot, etc.), the differences in what each measures, and the reality that sensors often disagree, degrade over time, or aren’t fully reliable. People noted the value of integrating multiple monitors—indoor and outdoor—into a centralized dashboard using Home Assistant, which can automate ventilation, ERVs/HRVs, and other smart devices for whole-house IAQ control. They also learned that monitoring accuracy varies, that apps and connectivity can be unreliable, and that most devices don’t directly detect mold but instead track conditions that support it. Remaining questions center on how to “put it all together”: how to select the right mix of sensors, how to integrate them reliably with Home Assistant, how to automate equipment effectively, how to handle sensor accuracy/maintenance over time, and how to create a simple, homeowner-friendly system in a still-developing ecosystem.
Abstract
Indoor air quality (IAQ) is a cornerstone of human health, comfort, and building performance. As people spend more time indoors—often in homes that are tightly sealed for energy efficiency—the ability to measure and manage pollutants becomes essential. Modern consumer IAQ monitors now offer insights previously available only through specialized testing, allowing sustainability professionals, builders, contractors, and homeowners to better understand the dynamics of their indoor environments. When this monitoring is paired with mechanical ventilation, dehumidification, and home automation platforms, residential spaces can become responsive systems that actively support occupant health. This article explores the current state of IAQ monitoring, what these devices reveal, how to interpret their readings, and how emerging automation strategies can create healthier and more resilient homes, drawing upon practitioner observations and real-world field data.
Understanding the Changing Landscape of Home Indoor Air Quality
Indoor air quality has surged to prominence as scientific literature, public health discussions, and building codes increasingly highlight the connections between air pollutants and human well-being. With individuals spending the vast majority of their time indoors, and with the move toward remote work accelerating this trend, the conditions inside homes have become central to personal health. Many homes, especially older ones or those lacking modern mechanical ventilation strategies, cannot effectively dilute or remove pollutants. Historically, homeowners relied on periodic inspections or professional-grade monitoring to understand indoor conditions. Today, affordable IAQ devices have revolutionized access to real-time environmental data.
These monitors provide visibility into a range of factors—particulate matter, carbon dioxide, total volatile organic compounds, humidity, and temperature—that influence both comfort and health. Even if consumer monitors are not scientifically precise, they reliably indicate changing conditions and pollutant-generating events. Their great strength lies in showing trends and enabling timely action, whether by opening windows, activating exhaust systems, or initiating mechanical ventilation.
As IAQ monitoring becomes more accessible, professionals across the sustainability and building sectors are increasingly integrating these tools into their practice. This reflects a broader recognition that indoor environments are dynamic ecosystems requiring ongoing attention, particularly in energy-efficient homes where mechanical systems play an essential role in air exchange.
Key Pollutants and What Monitoring Reveals
Particulate Matter (PM2.5)
Particulate matter measuring 2.5 microns or smaller is among the most concerning pollutants for indoor environments. Cooking consistently emerges as a major source of PM2.5 emissions in homes. Whether using gas or electric equipment, high-heat cooking releases fine particles from heated oils and food. Range hoods that do not extend over front burners, or over-the-range microwaves with shallow capture zones, often fail to contain these emissions. IAQ monitors detect these spikes quickly, providing clear, visual evidence of when ventilation strategies are insufficient.
Volatile Organic Compounds (VOCs)
VOCs originate from cleaning products, building materials, fragrances, combustion appliances, and even everyday household activities. Certain appliances, such as alcohol-fueled siphon coffee makers, can cause sharp VOC increases. Monitors reveal these episodes clearly, helping users understand when additional ventilation or behavioral adjustments may be necessary.
Carbon Dioxide (CO₂)
Carbon dioxide levels are a reliable indicator of whether a home is receiving adequate fresh air. CO₂ tends to rise in occupied spaces, especially bedrooms overnight, when doors are closed and ventilation is minimal. While CO₂ is not toxic at typical indoor levels, elevated concentrations can impair cognitive function and cause fatigue. Many experts consider levels above 800–1,200 ppm to be potential indicators that fresh air should be introduced. It is important to note that some consumer monitors report “CO₂ equivalency” based on VOC levels rather than actual CO₂ measurements. These approximations are often unreliable and should not guide mechanical ventilation decisions.
Humidity, Temperature, and Dew Point
Humidity strongly affects comfort, indoor durability, and mold risk. Sustained high humidity in basements, utility rooms, and poorly ventilated areas can lead to condensation and material deterioration. Dew point readings are particularly useful for identifying whether surfaces are at risk of moisture accumulation, yet few devices report dew point directly. Monitoring humidity and temperature together provides a more complete picture of moisture behavior throughout a home.
Radon and Mold Risk Indicators
Some IAQ devices measure radon, while others calculate mold-risk indicators based on humidity, temperature, and time. Although these tools do not detect mold spores, they highlight conditions conducive to microbial growth. In many cases, IAQ monitoring has uncovered problems such as inactive radon mitigation systems that would otherwise go unnoticed for long periods. When interpreted correctly, these readings help homeowners take preventative action before minor issues escalate.
The Importance and Limitations of Multi-Sensor Strategies
As homeowners add more IAQ devices—often from different manufacturers—they gain a richer understanding of their indoor environment. While individual readings may differ slightly between devices, what matters most is how consistently they respond to real events. When monitors from different brands simultaneously detect PM2.5 spikes during cooking or humidity increases after showers, occupants gain confidence in the accuracy of the trends.
Different monitors excel in different environments. Outdoor sensors mounted in backyards often reveal significant differences from regional air-quality reports, especially when nearby grilling, fire pits, or neighborhood activities influence immediate conditions. Bedroom monitors highlight nighttime CO₂ buildup, while basement sensors track humidity or radon trends that do not affect upper floors. This mosaic of data allows building professionals to diagnose issues in specific zones of a home rather than relying on whole-house averages.
However, having multiple devices also introduces complexity. Many homeowners, even highly engaged ones, rarely check their apps or cloud dashboards consistently. The sheer volume of data becomes overwhelming without a simplified interface or automated response mechanisms. This growing challenge has created the demand for systems that consolidate data and make it operational—either visually or through intelligent control systems.
Source Control and Practical Mitigation Strategies
IAQ monitoring empowers occupants to take corrective actions as soon as issues arise. A consistent theme across field observations is the importance of using available exhaust systems during pollutant-generating activities. Range hoods and bathroom fans, even when imperfect, substantially reduce pollutant levels when operated correctly. Opening windows can assist with flushing out indoor pollutants, especially when outdoor air quality is favorable. Some cultures normalize this practice with morning ventilation rituals designed to refresh indoor spaces.
When pollutants such as CO₂, humidity, or particulates regularly rise above acceptable thresholds, mechanical ventilation becomes essential. Energy recovery ventilators (ERVs) and heat recovery ventilators (HRVs) provide balanced ventilation while preserving heat and moisture, making them suitable for nearly any climate. These systems reliably dilute pollutants and maintain healthier indoor environments, especially when paired with filtration and dehumidification.
It is important to acknowledge that fostering healthy indoor environments can increase energy use. Ventilation, filtration, and dehumidification require electricity, and there are times when maintaining health must take precedence over minimizing energy consumption. This balance is a recurring theme in sustainable building practice: good indoor air quality is part of overall building performance, not an optional add-on.
When high humidity persists, whole-home dehumidifiers become an important element of IAQ management. As fresh air is introduced, especially in humid regions, moisture loads must be controlled to prevent condensation and deterioration. Properly sized and strategically installed dehumidifiers play a critical role in maintaining both IAQ and building durability.
Home Assistant: A Flexible Open-Source Platform
Home Assistant, an open-source home automation environment, has emerged as one of the most adaptable and powerful tools available for integrating indoor air quality monitoring with whole-home controls. Although it requires a modest level of technical comfort, the platform offers nearly unlimited configurability. Users have successfully brought together an array of IAQ sensors from different manufacturers, allowing carbon dioxide levels, particulate matter trends, volatile organic compound readings, and other environmental data streams to appear side by side in a single unified interface. The system also supports the integration of smart thermostats such as Ecobee, making it possible for occupants to view and adjust temperature or ventilation settings directly within Home Assistant without needing to toggle between multiple proprietary apps.
Beyond sensors and thermostats, Home Assistant can control a range of mechanical devices. Energy recovery ventilators and whole-home dehumidifiers can be connected through smart relays, enabling automated operation even when the original equipment does not include smart-enabled features. This allows the platform to respond dynamically to changing conditions—for example, by activating a ventilation boost mode whenever indoor CO₂ surpasses a selected threshold, or by increasing airflow in response to elevated particulate levels. Home Assistant can also incorporate data from external sources, such as outdoor air quality indexes or real-time electricity pricing, enabling load-shifting strategies or pollutant-aware ventilation schedules that balance health needs with energy considerations.
The heart of the platform’s value lies in its ability to weave these disparate inputs into conditional logic. Complex rules governing equipment performance can be created through a user-friendly interface, allowing homeowners and professionals to define exactly how the mechanical systems should behave under different indoor or outdoor environmental scenarios. When conditions are met—such as a spike in PM2.5 or a stagnant period of overnight CO₂ accumulation—the platform automatically executes predefined actions. This capacity transforms Home Assistant into a central nervous system for the home, coordinating the operation of ventilation, filtration, and dehumidification equipment in ways that were previously possible only through high-end commercial building automation solutions.
Equally important is the visual component. Home Assistant supports detailed dashboards that allow users to compare sensors, track pollutant trends, and observe how equipment responds over time. CO₂ patterns across bedrooms, VOC fluctuations in living areas, PM2.5 behavior during cooking, or humidity changes in basements can all be plotted together. These charts help reveal underlying issues—such as an underperforming range hood, a radon mitigation system that has shut down, or a bedroom that accumulates excessive CO₂ during sleep—allowing both troubleshooting and long-term optimization. For sustainability professionals, this unified visualization transforms scattered device data into clear, actionable intelligence.
While Home Assistant is not the only platform capable of managing IAQ-related automation, its openness, flexibility, and active development community make it an especially powerful option for those willing to explore its capabilities. For users who prefer a more turnkey experience, integrated commercial systems such as Haven IAQ offer simplified but less customizable alternatives. In either direction, the convergence of monitoring and automated control signals a future in which residential indoor environments become increasingly intelligent and responsive to real-time conditions.
Professional Applications and the Future of IAQ Management
As IAQ monitoring becomes more common, professionals across the building and sustainability fields are exploring new ways to incorporate it into practice. Builders sometimes leave behind monitors in new homes as part of a client education strategy. HVAC contractors are beginning to package sensors with ventilation equipment, providing homeowners with remote insights into system performance. Some consultants are experimenting with replicable Home Assistant configurations that can be deployed across multiple homes, although long-term maintenance and troubleshooting remain challenges.
Despite these hurdles, the direction of the industry is clear. Residential IAQ monitoring and control will continue to evolve toward integrated systems that provide both visibility and automation. As this convergence accelerates, homeowners will increasingly expect buildings to respond intelligently to environmental conditions, providing health-protective air quality with minimal effort. For sustainability professionals, builders, and contractors, this shift offers both an opportunity and a responsibility: to ensure that healthier homes are not only technically achievable but accessible, maintainable, and grounded in sound building science.
The Green Home Institute remains committed to supporting this transition by offering education and resources that empower people to make healthier, more sustainable choices in the places they live.
Key Takeaways
- Indoor air quality has major impacts on health and building durability, and affordable monitoring technologies now make it easier to assess pollutant levels in real time.
- Cooking is a significant source of particulate matter, and effective ventilation is essential regardless of whether homes use gas or electric appliances.
- CO₂ readings provide crucial insights into ventilation adequacy, while VOCs and humidity trends reveal additional indoor air patterns.
- No consumer device presently detects mold spores directly; instead, they report the environmental conditions that support mold growth.
- Mechanical ventilation systems such as ERVs and HRVs help manage CO₂ and humidity, but they may increase energy use—indicating that health sometimes takes precedence over efficiency.
- Home Assistant offers a flexible, open-source pathway to integrating multiple IAQ sensors and mechanical systems into automated environmental control.
- Dashboard visualizations in Home Assistant help identify patterns, diagnose equipment failures, and monitor pollutant behavior across rooms.
- Turnkey IAQ automation platforms such as Haven IAQ exist for users who prefer less technical customization.
- Builders and contractors increasingly view IAQ monitoring as part of modern high-performance home design.
- The future of IAQ management lies in homes that automatically respond to pollutant events, occupancy patterns, and changing indoor conditions.
Question and Answer Responses from the Webinar
Q: Are you using an electric stove or gas? Does that make a difference?
A: Scott is using gas, and Brett is using electric resistance. These make a huge difference. Check out the webinar recording, and you will see the results of Pm2.5 from gas, and for Brett, there is still some Pm2.5, but it is a lot lower.
A: Scott is using gas, and Brett is using electric resistance. These make a huge difference. Check out the webinar recording, and you will see the results of Pm2.5 from gas, and for Brett, there is still some Pm2.5, but it is a lot lower.
Q: Have you found that certain monitors are less effective over time? That the sensors deteriorate and become inaccurate?
A: Scott – Yes, for example, the Kaiterra shows sensor health and tells you when to replace. That is really the best way to approach it. Otherwise, sensors will drift over time. I haven’t seen a replacement protocol for the typical consumer devices though. Brett – I have seen both with PM2.5 get dusty and escalate the pm2.5 numbers higher than what is true, but it has not happened to all the devices.
A: Scott – Yes, for example, the Kaiterra shows sensor health and tells you when to replace. That is really the best way to approach it. Otherwise, sensors will drift over time. I haven’t seen a replacement protocol for the typical consumer devices though. Brett – I have seen both with PM2.5 get dusty and escalate the pm2.5 numbers higher than what is true, but it has not happened to all the devices.
Q: Are there devices that check for mold?
A: Usually, samples are sent to a lab for testing. There is an electronic tool mold contractors use called InstaScope that will pick up mold spores on-site but not an IAQ monitor that gives a mold score
A: Usually, samples are sent to a lab for testing. There is an electronic tool mold contractors use called InstaScope that will pick up mold spores on-site but not an IAQ monitor that gives a mold score
Q: Can you shed some light on the Blower Door test, and when the home is too tight, and what that does to IAQ?
A: A blower door test will tell you how leaky a home is. From there you can use https://redcalc.pnnl.gov/ to look at what the ventilation is, depending on how leaky the home is. The good news is that with IAQ monitors, you’ll get real data on what is needed, and then use ventilation to adjust it to a healthy level.
A: A blower door test will tell you how leaky a home is. From there you can use https://redcalc.pnnl.gov/ to look at what the ventilation is, depending on how leaky the home is. The good news is that with IAQ monitors, you’ll get real data on what is needed, and then use ventilation to adjust it to a healthy level.
Q: Do you have suggestions for air quality sensors that are more detailed with specific VOC groups, not only a total VOC measurement?
A: Scott – Sadly, I don’t think this exists yet, at least at the residential consumer level. I suggest a guess and check method – for example, if you are using a product that increases the VOC levels, look more closely at that product and see if you can discern what chemical it is from the Safety Data Sheet. Brett – I do believe some sensors do detect formaldehyde now, though, which is usually the most concerning VOC.
A: Scott – Sadly, I don’t think this exists yet, at least at the residential consumer level. I suggest a guess and check method – for example, if you are using a product that increases the VOC levels, look more closely at that product and see if you can discern what chemical it is from the Safety Data Sheet. Brett – I do believe some sensors do detect formaldehyde now, though, which is usually the most concerning VOC.
Q: What does “make it tight, ventilate right” mean?
A: It means make your home as air-tight as possible through good construction and air sealing, and then follow the ventilation protocols of ASHRAE 62.2 to do proper ventilation.
A: It means make your home as air-tight as possible through good construction and air sealing, and then follow the ventilation protocols of ASHRAE 62.2 to do proper ventilation.
Q: What do you recommend to track outdoor air quality, especially for a house near a busy street?
A: There are several manufacturers. I have a PurpleAir and like it!
A: There are several manufacturers. I have a PurpleAir and like it!
Q: Isn’t a zero PM2.5 reading a bit suspicious?
A: In many cases, modern low-cost sensors can’t distinguish low concentrations of PM2.5, so manufacturers opt to display zero.
A: In many cases, modern low-cost sensors can’t distinguish low concentrations of PM2.5, so manufacturers opt to display zero.
Q: Do you have any CO2 or VOC data I can show my girlfriend about burning a bunch of candles?
A: Scott – Sadly no, we stopped using candles once we knew they were bad for IAQ! Brett – I have found that most candles put out mild VOCs sometimes and high PM 2.5 often when you blow them out, which is short-lived.
A: Scott – Sadly no, we stopped using candles once we knew they were bad for IAQ! Brett – I have found that most candles put out mild VOCs sometimes and high PM 2.5 often when you blow them out, which is short-lived.
Q: What brand of Wi-Fi relays should I consider for use with Home Assistant, and where can I source them?
A: Shelly is what the Home Assistant community loves and recommends. Amazon has them!
A: Shelly is what the Home Assistant community loves and recommends. Amazon has them!
Q: How can I trust the data from multiple IAQ monitors in my mechanical room? What are these different sensors reporting? (Awair, Kidde, CERV)
A: I’d look at the spec sheets, compare the sensor types, and their +/- reporting range. And always make sure to calibrate per manufacturer’s recommendations!
A: I’d look at the spec sheets, compare the sensor types, and their +/- reporting range. And always make sure to calibrate per manufacturer’s recommendations!
Q: Which systems support Matter over Thread protocols to facilitate management, automation, and alarms? Which manufacturers are advancing Matter-over-Thread to integrate their systems with other building systems?
A: I haven’t gotten into Matter over Thread yet. I’m using primarily Wi-Fi and Zigbee control devices. I have had great luck with Shelly relays to do this.
A: I haven’t gotten into Matter over Thread yet. I’m using primarily Wi-Fi and Zigbee control devices. I have had great luck with Shelly relays to do this.
Q: Which IAQ device is the front runner without using home automation software?
A: I generally recommend Airthings View Plus.
A: I generally recommend Airthings View Plus.
Q: Can the PurpleAir be integrated with an ERV?
A: It can be if you integrate it in the DIY Home Assistant way like I have done.
A: It can be if you integrate it in the DIY Home Assistant way like I have done.
Q: What would be the investment cost for a system like the ones discussed?
A: My system is quite expansive, but to get off the ground you’re looking at approx: $50-$100 for a computer to run Home Assistant (can be a Raspberry Pi), $100-$200 for a smart thermostat, $200-$300 for an IAQ monitor. From here, it depends where you want to go… an ERV can be several thousand dollars, etc.
A: My system is quite expansive, but to get off the ground you’re looking at approx: $50-$100 for a computer to run Home Assistant (can be a Raspberry Pi), $100-$200 for a smart thermostat, $200-$300 for an IAQ monitor. From here, it depends where you want to go… an ERV can be several thousand dollars, etc.
Q: Do you have a how-to guide online?
A: Intro article I wrote is here: https://www.linkedin.com/pulse/smart-living-how-i-use-home-assistant-optimize-my-life-scott-farbman-srxgc
A: Intro article I wrote is here: https://www.linkedin.com/pulse/smart-living-how-i-use-home-assistant-optimize-my-life-scott-farbman-srxgc
Content editing was done by ChatGPT and Zoom
