Why Insulation and Good Design Beat Green Gizmos
Green building can be so confusing; there's Passivhaus, Passive House US, Net Zero and Near Zero energy buildings. Fundamentally, it comes down to two different philosophies: in Passivhaus, you want to put in so much insulation and such high quality windows that you barely need to heat or cool at all, minimizing energy use; In Net Zero, you want to generate enough power on site to heat, cool and light your house; it could be a draughty barn, but if you put enough green gizmos on the roof to generate enough green energy to feed it, who cares?
It may be worth mentioning that I view this as an apples v. brownies issue (I’ll leave you, dear reader, to decide which is which). On one hand, extreme comfort and consumption reduction (Passivhaus); on the other, energy production (which may or may not entail significant energy conservation measures).
© Mike Eliason/ Any crappy old house can be net zero if you put enough stuff on the roof
I am not certain that they are so far apart that they are not even apples vs oranges, but there is an important distinction between the two: One is simple and well, passive. The other is very active, requiring maintenance and monitoring. Eliason goes through a lot of reasons why he thinks that the Passive first approach makes sense, but ultimately the most convincing one for me is its resilience:
A grid-tied PV won’t keep you warm at night during a blackout. Roger Lin’s Arlington Passivhaus lost power for nearly two insanely hot and muggy days last summer. How’d the house perform? Extremely well: “While the outdoor temperature was 92 degrees, the basement was a comfortable 73 degrees. First floor was a warm but not unpleasant 81 degrees. Second floor was 79 degrees… Insulation really works.....
And, as Greg Duncan recently tweeted, the “Winter of ‘extreme storms’ is new norm. Passivhaus ensures comfort from drafts, cold; resilience against outages and respite from loud winds.”
Whether it’s holding in heat, keeping the heat at bay, or reducing external noise, Passivhaus bests a zero-energy building in nearly every case. Another way to think about it: Don’t like living next to that loud street or in that airport approach? Maybe you could use your solar panel as a sound barrier!
There is, of course, the compromise: The Passive House (or near passive house) with a little PV array on top, like the Belfield by Onion Flats shown above. You don't need a whole lot of the stuff to keep the lights on.
I have never been a fan of Green Gizmo design, where everything gets so complicated and expensive. But there are also issues with Passive Houses, and questions about whether so much insulation is serious overkill. Perhaps the compromise we need is closer to what is becoming my favorite standard, the Pretty Good House. (PGH)
Read it all at Green Building Advisor