17 May 2011
Reducing a building’s heating energy use by 70 to 90 percent can be achieved with three basic ingredients: (1) highly insulated walls and windows, (2
Reducing a building’s heating energy use by 70 to 90 percent can be achieved with three basic ingredients: (1) highly insulated walls and windows, (2) a tightly sealed envelope, and (3) heat recovery ventilation. Not rocket science, but common sense applications of the principle of “efficiency first.”
And those are the three key components of “Passivhaus” design, a highly energy efficient building construction standard that has been successfully applied in more than 25,000 buildings in Europe. So far, only a handful have been built in the U.S. You might wonder—as I have written previously—what’s our excuse?
The photo above shows Dan Whitmore’s nearly completed Courtland Place Passive Project, Seattle’s first permanent building designed to the Passivhaus standard (the Mini-B Passive House isn’t a permanent structure).
The mother-in-law unit has been occupied for two months, and according to Whitmore so far the heat was turned on for a grand total of about five minutes on one especially frosty morning in March. Aside from that brief lapse, the excess heat generated by appliances, people, and the sunlight coming through the windows was enough to keep it comfortably warm inside. I can attest that the space was warm, almost too warm, on the partly sunny but cool spring day of the Ecobuilding Guild’s recent green home tour.
And yes, the heat recovery ventilator has to run 24×7 in cold weather when the windows are closed, but it only consumes about as much as a 50 watt light bulb. Whitmore’s house has no furnace—a significant up front cost savings. On the coldest days it can be heated with two small baseboard electric heaters, or by running water from the domestic hot water tank through the heat recovery ventilator.
But is it expensive? A recently completed Passivhaus in Portland reportedly had a 10 percent cost premium over conventional construction (the windows are a major part of that premium). In Germany where contractors have experience with the standard, typical cost premiums run five to eight percent.
But the reduction in energy use provides both a direct cost payback that is guaranteed to sweeten as energy prices inevitably rise, and a public benefit payback from a reduction of the myriad externalized costs associated with energy consumption. And then there’s the potential payback in “green jobs.” What if all those triple pane windows were manufactured locally?
Furthermore, the impact of “efficiency first” strategies like Passivhaus tend to have broad, positive repercussions across systems. For example, would there be any need for a major investment in district heating systems at Yesler Terrace if most of the buildings were designed to the Passivhaus standard? Seattle City Light gives away fluorescent light bulbs for the same underlying reason.
At this stage in the climate change/peak oil game, projects like Whitmore’s Passivhaus ought to be the norm for new construction. And to help make that happen we desperately need meaningful incentives at the local, State, and Federal levels. Preferably yesterday, please, if not sooner.