Remember that whole “tight is right” insulation discussion?  Multiple blower door tests in the contract?  C-R-U-S-H-I-N-G our 2nd standard on our first try?  Little pigs?

The good news is that we’re well on our way to an incredibly efficient home.  According to a couple of our geothermal engineering estimates, Dash Landing’s heating bill for the average Maine winter should be right around $800.  Words alone cannot convey this amount of awesomeness, nevermind the most excellent karma of a lower environmental footprint.  And that’s before we add solar PVs.

But there’s a potential downside of a tight house — air quality.  Between people, pets and everyday living, there’s a high likelihood that things could get “stale”  — at best.  Even unhealthy.

That’s where our heat recovery ventilator (HRV) comes in.  One of this week’s projects was the completion of our mechanical air exchange system.  There’s a fantastic article here about HRVs with more detail than you’d ever want to know, but this drawing explains the basics :

Stale air circulates into the system where it’s exchanged with fresh air from the outside.  In the process, the heat is recaptured and warms the incoming air.  (There’s something magical in that square core.  We suspect unicorn tears.  Maybe leprechaun wishes.)  We don’t believe these are part of the building code in Maine yet, but there’s no doubt that a mechanical air exchange requirement is coming eventually.  (And please don’t email us with nitwit things like “As soon as we finish fighting the incandescent light bulb ban, we’re going after these things.”  Life is far too short for that nonsense.)

In our case, we’re installing an Imperial 7.15ES HRV made up the road in beautiful New Brunswick, Canada.  It’ll run continuously at a low-speed, but each of the bathrooms will have a timer switch that will kick the HRV into high-speed mode for a fixed amount of time — typically in 20 minute increments.

Together with the air purifier and humidifier that are spec’d in the package and we’d like to think that Dash Landing will be a pretty comfortable place.

Even for W.