New Codes Mandate Mechanical Ventilation. Here’s Why ERVs Are the Best Option
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A few years ago, you might get by in your home without mechanical ventilation. But walls are tighter, toxins are better understood, and ERVs solve multiple challenges.
If you haven’t heard of an Energy Recovery Ventilator (and many people have not) you may want to catch up. This technology, along with Heat Recovery Ventilators (HRVs), have hit the mainstream in the new home market.
Building science developed these devices decades ago, and manufacturers have refined them. They’re basically multi-layer ventilation devices that “exchange” the energy used to heat or cool your home’s air with fresh outdoor air. As a result, you can bring fresh air into your house all year, with minimal impact on your energy bill.
Newer building codes have set stricter rules for home ventilation. While codes written before about 2000 assumed that “makeup” air could enter the house passively--through leaky walls or windows--the 2021 International Residential Code mandates mechanical ventilation.
Based on ASHRAE standards, this rule is based on a minimum number of air changes per hour (ACH) in a new home. The idea is that a house needs to “exhale” the buildup of VOCs and other airborne pollutants at regular intervals.
ERVs solve what can be tricky balancing problems with the old way of putting in a bath fan and/or kitchen range hood and passive vents. When those one-way fans blow air out of the house, the fresh air that enters is a cold or hot as the outdoor environment. It may also be polluted with wildfire smoke or other particles.
How Residential Ventilation Rules Evolved
Tough Times Call for Better Equipment
Of course, ERVs can (and probably should) be installed in many existing homes, as well. I have installed a few myself, and the effect they have on indoor air quality has been life changing. I put one in a Florida home, for instance, and tracked the impact on CO2 levels in bedrooms. High levels were literally making my family sick, and the problem went away the moment I turned on the ERV switch.
But the case for ERVs goes deeper and wider than you might expect. For example one of the biggest, least known polluters in the typical house is the kitchen range. Homeowners don’t use their range hoods, or use them improperly. They can create a vast imbalance in pressure levels in the home.
Then there’s the dire impacts of outdoor wildfire smoke that seems to reach much of the U.S. for much of the year. Most ERVs contain filtration to catch smoke particles. Some can be put into a “recirculation mode” so they stop sucking smoke into the house.
There’s a lot more to say about ERVs, but rather than ramble on here, I encourage you to join me for an hour-long webinar on the topic on September 18th. It’s sponsored by Panasonic, but I’ll be leading the discussion and we’ll be fielding tough questions like “should I install an ERV or and HRV?” and “why can’t I just run my bath fan all the time?” and so on.
Veteran journalist Matt Power has reported on innovation and sustainability in housing for nearly three decades. An award-winning writer, editor, and filmmaker, he has a long history of asking hard questions and adding depth and context as he unfolds complex issues.
New Codes Mandate Mechanical Ventilation. Here’s Why ERVs Are the Best Option
A few years ago, you might get by in your home without mechanical ventilation. But walls are tighter, toxins are better understood, and ERVs solve multiple challenges.
If you haven’t heard of an Energy Recovery Ventilator (and many people have not) you may want to catch up. This technology, along with Heat Recovery Ventilators (HRVs), have hit the mainstream in the new home market.
Building science developed these devices decades ago, and manufacturers have refined them. They’re basically multi-layer ventilation devices that “exchange” the energy used to heat or cool your home’s air with fresh outdoor air. As a result, you can bring fresh air into your house all year, with minimal impact on your energy bill.
Newer building codes have set stricter rules for home ventilation. While codes written before about 2000 assumed that “makeup” air could enter the house passively--through leaky walls or windows--the 2021 International Residential Code mandates mechanical ventilation.
Based on ASHRAE standards, this rule is based on a minimum number of air changes per hour (ACH) in a new home. The idea is that a house needs to “exhale” the buildup of VOCs and other airborne pollutants at regular intervals.
ERVs solve what can be tricky balancing problems with the old way of putting in a bath fan and/or kitchen range hood and passive vents. When those one-way fans blow air out of the house, the fresh air that enters is a cold or hot as the outdoor environment. It may also be polluted with wildfire smoke or other particles.
How Residential Ventilation Rules Evolved
Tough Times Call for Better Equipment
Of course, ERVs can (and probably should) be installed in many existing homes, as well. I have installed a few myself, and the effect they have on indoor air quality has been life changing. I put one in a Florida home, for instance, and tracked the impact on CO2 levels in bedrooms. High levels were literally making my family sick, and the problem went away the moment I turned on the ERV switch.
But the case for ERVs goes deeper and wider than you might expect. For example one of the biggest, least known polluters in the typical house is the kitchen range. Homeowners don’t use their range hoods, or use them improperly. They can create a vast imbalance in pressure levels in the home.
Then there’s the dire impacts of outdoor wildfire smoke that seems to reach much of the U.S. for much of the year. Most ERVs contain filtration to catch smoke particles. Some can be put into a “recirculation mode” so they stop sucking smoke into the house.
There’s a lot more to say about ERVs, but rather than ramble on here, I encourage you to join me for an hour-long webinar on the topic on September 18th. It’s sponsored by Panasonic, but I’ll be leading the discussion and we’ll be fielding tough questions like “should I install an ERV or and HRV?” and “why can’t I just run my bath fan all the time?” and so on.
Here’s the site where you can sign up for the Webinar. I hope to see you there.
By Matt Power, Editor-In-Chief
Veteran journalist Matt Power has reported on innovation and sustainability in housing for nearly three decades. An award-winning writer, editor, and filmmaker, he has a long history of asking hard questions and adding depth and context as he unfolds complex issues.Also Read