The idea that a house could generate nearly all the energy needed for heating & cooling onsite seems very futuristic. We often assume that passive house principles can only be incorporated into new designs, often with a decidedly modern feel. That’s an assumption Whitney Architecture and Seattle new home builder Hammer & Hand are working to prove false.
Contrary to what we might believe, the aforementioned builders claim passive house design and construction is all about flexibility. When a client asked them to build a passive house that hearkened back to a traditional aesthetic on a lot rife with shade trees, they knew they would have to be creative, but were excited for the challenge.
For those unfamiliar, a passive house “is a very well-insulated, virtually air-tight building that is primarily heated by passive solar gain and by internal gains from people, electrical equipment, etc, “explains The Passive House Institute US. “Energy losses are minimized. Any remaining heat demand is provided by an extremely small source.”
At first glance, a lot surrounded by beautiful, mature shade trees doesn’t sound like the right place for this type of construction project, but the designers didn’t give up.
“To compensate for these challenges, we will clad the wood framed walls of the Maple Leaf Passive House in a somewhat thicker layer of Polyisocyanurate (poly-iso) foam – four inches instead of three – giving the walls an additional 12% of insulative value when in assembly,” states Hammer & Hand.
The Maple Leaf Passive House will be constructed atop a layer of EPS geofoam using, in this case, a structural raft slab. It “will incorporate an HRV (heat recovery ventilator) for 24/7 fresh air supply and a minisplit heat pump for heating,” continue the designers. “Pervious pavement will reduce stormwater runoff and a 3,000-gallon cistern will capture rainwater for non-potable domestic use.”
The lesson here, according to Whitney Architecture and Hammer & Hand, is that “as long as you hit the mark for airtightness, heating demand/load (and cooling demand/load were we to be in a warmer climate), and primary energy use, you’re golden – any architectural style is okay, any site works.”
Watch their progress on the Maple Leaf Passive House in the video below: