Unfortunately, the words Passive House often, incorrectly, evokes images of out-there home designs of the 70′s and 80′s… sporting Trombe Walls and double-pane windows that fill with styrofoam beads when the sun goes down.
For clarity, there’s a Passive House and there’s a passive solar house (what I described above goes with the latter). A Passive House is designed and built to exacting standards, performance tested, then certified versus a passive solar house built to take advantage of the sunshine that we don’t have.
Here we go, in a nutshell.
Passive House: Passive House, is an approach to design and construction that relies on a super efficient envelope, essentially minimizing losses to optimize gains (like body heat, cooking heat, and drying clothes), with a super efficient envelope, you get to keep all that heat. There is a component of optimizing solar gains to Passive House, it shares this in common with the solar movement, but its primary focus is conservation and minimizing of energy demands. The Passive approach yields (in any climate with any level of exposure, I might add) 75%-90% more efficient structures, combine this with the other elements necessary to a Passive House, like ample fresh air delivery, and high performing windows, you end up with a substantially more comfortable, affordable and healthy house.
Passive solar house: Passive solar houses rely on optimal orientation to collect the sun’s heat, large thermal masses to store that heat, and climates with dramatic diurnal swings. The caveat to the approach is that we don’t all have ideal sun exposures, and suitable climates, not to mention that those windows that let the heat in, will also let the heat out.
When I was studying building science in school, back in the mid 80′s, I happened to live in Colorado where they get 370 days of sunshine per year, and lots of snow… a wonderful venue for applying passive solar. I remember one field trip where we went to a home that was built to maximize solar gain and had sufficient thermal mass that the home had a year round temperature swing of 4 degrees. Pretty impressive. Colorado is the mecca where passive solar design really shines, forgive the pun.
Now, the Passive House design standards allow all the non-mecca states to achieve a level of passive comfort unheard of in the building trades. Noteworthy is the outstanding payback period of an upgrade to Passive House standards. In most cases, it’s under 6 years.
That’s the very basic difference between the two. Hope that clarifies things for some of you, if you have questions, leave a comment or give us a call!