Cold-Climate Passivhaus Construction Costs
Three new homes cast doubt on the idea that it’s too expensive to build to the Passivhaus standard in cold climates
Now, that’s not to say that meeting the Passivhaus standard in certain localities is a walk in the park – it’s certainly difficult in many places, like Siberia; the north slope of a steep, east-west valley (Graubünden!); Fairbanks… That being said, there are projects (certified, even) that meet the Passivhaus standard in climates north of 7,000 heating degree days (HDDs) – and with the advent of something like Super Windows - well, much of that nonsense could become completely moot.
In the next year, I’m certain we’ll see several more projects that disprove the cost-ineffectiveness of meeting 15 kWh per square meter in cold climates. It is definitely something that merits debate – but hey, it’s not like anyone’s been censoring posts, or anything…
Chris Corson's Maine Passivhaus
The first project is the house that Chris Corson (the owner of EcoCor Design/Build) recently wrapped up in Knox, Maine. The project has seen some good press (including a GBA story) and great praise recently – I ran into many people at the recent Passivhaus conference in Hannover, Germany, discussing it, including some Canadians and Germans.
The 1,600-square-foot two-bedroom house sports a treated floor area of 1,140 square feet (106 m²), which some would say falls under the “small” category. It also happens to be a detached home in a really cold climate (modeled at 7,345 HDDs). Chris was able to bring the cost of construction to under $130/sf.
The modeling bests the specific space heating demand, coming in at 3.11 kBTU1,000 Btus/ft²a (9.82 kWh/m²a). This was done through a combination of superinsulation, phenomenal windows (from Intus) and a phenomenally low blower door test of 0.286 ach50.
The most impressive bit about getting the space heating demand so low, outside of achieving affordability in a difficult climate, was leaving wiggle room for future additions or modifications. Furthermore, cost savings may have been realized by dialing back the insulation closer to 4.75 kBtu/ft²a.
G•O Logic's red house
The second project is G•O Logic’s 1,500-square-foot, three-bedroom Passivhaus in Belfast, Maine – just down the road from the project above (by the way… WTF is up with Maine?!?).
This one also garnered lots of press, and recently snagged a LEED for Homes Project of the Year award. Yup, they were able to garner PH and LEED Platinum certifications for ~$160/sf. You can read up more on the project at Maine Home + Design.
The NewenHouse Passivhaus in Wisconsin
The third project throwing a wrench in the ever-weakening argument is the über-compact NewenHouse in Viroqua, Wisconsin (7,795 HDDs), with Carly Coulson as the certified Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. designer. This tiny (968-square-foot) kit house has a treated floor area of 888 square feet (82.5 m²).
This project sports local windows and Cardinal triple-pane glass, while the doors are Energate. Like the Knox, Maine, Passivhaus, the NewenHouse is wrapped in a jacket of cellulose – and similarly comes in well under the specific space heating demand.
Carly recently presented the project at the Hannover Passivhaus conference. Here are some of the project specs:
- Space heating demand: 11.4 kWh/m²a (3.61 kBTU/ft²a)
- Primary energy demand: 104 kWh/m²a (32.9 kBTU/ft²a)
- Blower door: 0.51 ach50
- Wall U-factorMeasure of the heat conducted through a given product or material—the number of British thermal units (Btus) of heat that move through a square foot of the material in one hour for every 1 degree Fahrenheit difference in temperature across the material (Btu/ft2°F hr). U-factor is the inverse of R-value. : 0.09 W/m²K (R-63)
- Slab U-factor: 0.10 W/m²K (R-57)
- Roof U-factor: 0.06 W/m²K (R-94)
The project is also rocking a solar domestic hot water system (Velux) that is expected to provide nearly two-thirds of the domestic hot water needs, and a PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow. system for site net zeroProducing as much energy on an annual basis as one consumes on site, usually with renewable energy sources such as photovoltaics or small-scale wind turbines. Calculating net-zero energy can be difficult, particularly in grid-tied renewable energy systems, because of transmission losses in power lines and other considerations. energy.
The project went through BRE in Watford, UK, for Passivhaus certification, is Energy StarLabeling system sponsored by the Environmental Protection Agency and the US Department of Energy for labeling the most energy-efficient products on the market; applies to a wide range of products, from computers and office equipment to refrigerators and air conditioners. certified, and is expected to hit LEED for Homes Platinum.
Total cost for NewenHouse – including solar DHW, PV, and accessory structures – is a whopping $173/sf. If there was a LEED Titanium, this über-tiny Passivhaus in an “extreme” environment would surely qualify.
While these may not be the modernist jewels we tend to drool over – these are sound, extremely cost-effective houses and further proof that there is more of a bad design/shoehorning penalty in extremely cold climates – rather than a detached housing one. And if locally made PH windows and glass ever become available, that cost-effectiveness will only improve.
Mike Eliason is a designer at Brute Force Collaborative in Seattle, Washington.
- Naomi C.O. Beal
- G•O Logic
- Sonya Newenhouse
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