A newly built home in San Francisco, Residence 950, takes indoor air quality very seriously. Built in 2018 by Troon Pacific, the 9,500-square foot home on Russian Hill has hospital grade air filtration via a Zehnder whole-house ventilation system, which changes all the air in the home every two hours; a central whole-house vacuum system that keeps all areas allergen and dust-free and a below-grade air barrier to keep out all allergens and mitigate dust.
Ventilation, it seems, “is the new frontier for making houses healthy,” says Carl Seville, whose Atlanta-based SK Collaborative does green building consulting and certification. The EPA cites indoor air quality (IAQ) as one of the top five environmental risks to public health. And, a recent study shows that people spend 90% of their time indoors – whether in houses, offices, schools, cars. And, recent Berkeley Labs IAQ findings on ventilation suggest that when lots of people gather together in a small space, the CO2 they expel into the air can impact their health and cognitive performance. (So, you might not be able to blame the beer for your actions when you and your friends are packed into your kitchen.) Along with CO2, according to the National Environmental Education Foundation, indoor air is polluted with lead, dust mites, mold, radon, pests, carbon monoxide, pet dander, mold, and second hand smoke. Throw in some humidity and you encourage mold to grow.
Think about that as you take your next breath of indoor air and know that before the day is over you will breathe approximately 2,500 gallons of the stuff. It’s all enough to make you gasp – for fresh air.
While the top-of-the-line Zehnder products can be upwards of $10,000, we mere mortals, or at least those of us who don’t have $45 million for a luxury mansion, can still get fresh air into our homes. As Seville points out though, it’s not just about bringing in outdoor air but bringing in air from the right places. You don’t want to pull in air from your garage, for example.
What most older houses have now for ventilation are bathroom fans and kitchen range hoods to remove the bad air. Older homes may be leaky, so while you are getting some fresh air, you have no control over where it’s coming from. On top of that, your HVAC system won’t work efficiently. Newer homes are more tightly built. So, yes, they’re more efficient from an energy standpoint, but you may not be getting the fresh air you need.
Enter the HRV and ERV. Although they’ve been around a while, many people don’t know about them. But you should get to know them because you’re going to be hearing about them a lot in the next few years as more people focus on IAQ. Basically, these devices pull out the bad air and replace it with good air. (If you have an older home, the first thing you’d need to do is tighten it up for either of these to do their best work.)
An HRV, Heat Recovery Ventilation system, uses the heat from the stale indoor air that’s being exhausted to warm up the incoming fresh air; the two air streams merely pass by each other in the HRV’s core so they never mix. Overall, you are using less energy to bring the outside air to room temp.
The ERV, Energy Recovery Ventilation system, does things a little differently. It captures both heat and moisture, your indoor humidity. In winter, the system transfers the humidity from the indoor air being extracted to the incoming fresh (and dry) air. In summer, it pulls the humidity out of the outside air before it gets inside. You save energy by reducing the load on your air conditioning system and/or dehumidifier.
Talk with an HVAC professional to determine which system will work best in your house, in your climate and for your lifestyle. HRV costs, not including installation, run anywhere from $600 to $1,100 for a mid-size system (this assumes you already have ducts and a central HVAC system.) Similar-sized ERVs may cost $150 to $200 more.
Of course, if you do have a bigger budget for air scrubbing, you can invest in some of these other things that Troon included at Residence 950:
- Vents that look like a covered wall outlet and are flush with the wall, leading to a central location with a HEPA filter (air purifier) to ensure air is as clean as possible
- Various extensions/tools for the whole-house vacuum system located throughout the home, including a dust pan attachment in the kitchen so crumbs can be swept up and sent directly to the central location
- A sub-slab air and water barrier, which helps mitigate the risk of harmful gases such as radon and moisture from entering the home from below grade and influencing air quality.
- Active ventilation from a below-ground air barrier with a fan system releases harmful air outside of the home.
- A mud room with lockers and a built-in ventilated bench and shoe storage – to keep from tracking in allergens and pollutants. Closets and trash areas are also ventilated.
- Hard surface floors only – wood, stone – which are easier to clean than carpet and don’t collect dust or allergens.