Breathing Easy

Dear Tree-Huggers,

One of the issues that super-insulated buildings have that conventional buildings don't have to deal with is indoor air quality. Simply put, if your building doesn't leak, the air inside will eventually grow stale and toxic. Trouble is, if you simply vent the bad air, you're also losing energy because you're expelling the heated (or cooled) air, and you'll have to spend energy heating (or cooling) the makeup air. This is why traditional bathroom fans, kitchen vents, and laundry vents aren't energy efficient. They simply push the air out of the house, and with it, your precious heat.

So how do we replace the stale inside air with fresh air outside without losing the heat? This has to be done mechanically, with a great system called a heat an energy recovery ventilator (ERV). It's sort of like a combination of a super-efficient HVAC and a heat exchanger. I like to think of it as the "lungs" of the house. They breathe fresh air in, exhale the stale air, and they maintain temperature and humidity levels.



After much discussion and research, we decided to install a dedicated ERV rather than a combined HVAC/ERV. This is partly because we're doing radiant heat in the floors, and partly because a dedicated system will exchange the air quickly and more efficiently. The best system available is made by Zehnder. We worked with the fine folks at Zehnder, who designed our system based on the house plans we sent to them. They sent us the ERV units and all the necessary parts, and we had the pleasure of installing them ourselves. (It was terribly difficult to find an HVAC contractor willing to meet our exacting standards at a price we could afford, so yours truly spent vacation days doing the job).

My trusty assistant helping to run the air lines.

I did have help. First, the electrician helped me drill a bunch of 4" holes. Then, my dad and my husband (on different days) helped me to run the supply and return lines to each room. These were like very long wet-vac hoses. Each room in the house gets designated either a "supply" or a "return" room. For example, bedrooms will need fresh air, so they get supply lines. The bathrooms and laundry need to expel air, so they get "return" lines. Each line feeds back to a central location. This was quite labor intensive.  Good news is, the outlets are small and unobtrusive, so the finished look will be really clean.

After the install was completed, the insulators went to work, and then sheetrock covered the whole mess. Next week, a Zehnder rep will make a site visit to balance the system, which involves starting it, programming the machine, and making sure the controllers work properly. Fingers crossed!

Greenly Yours,

Parker