Passive House
Thank goodness for the warmth of its people, because it can get awfully cold in Saskatchewan. There is way more sky.
In response to the energy crisis created by OPEC in the 1970s, the Government of Saskatchewan instigated a research project to build an ultra-low energy house in the provincial capital, Regina. This was before people much worried about greenhouse gases or global warming; the government wanted to protect the people of the province in the case of a prolonged energy shortage. Using what is now almost primitive technology, the Saskatchewan Conservation House was able to decrease the energy used for heating and cooling by 85% compared to a conventionally-constructed building of the same size built at that time in that city.
The team of Canadians built what is now known as a Passive House, in fact the very first one. The term refers to the lack of active heating and cooling systems; there is no furnace, rather the heat is kept in with high- resistance-value insulation, super-tight construction and a super-efficient heat exchanger that warms incoming air with the air being expelled. In 1990, the Passive House Institute was founded in Darmstadt, Germany by Dr. Wolfgang Feist. Dr. Feist created software (known as PHPP), and refined the building science pioneered in Saskatchewan, that is now used worldwide. To be certified, Passive Houses must meet an ultra-low energy use standard, qualified by testing of air infiltration and heat loss, during and after construction.
Passive Houses (which can be apartment buildings and offices too) are usually built with special high-performance windows and must be detailed to eliminate all possible thermal bridges. The advanced heat exchangers used in Passive Houses can warm (or cool) incoming air with an efficiency of heat transfer approaching 90%. No air is recirculated, the air in every occupied room is completely replaced with fresh outdoor air every 3 hours or so. If it's nice outside, you can open the windows, but it is also simple to adjust the ventilation mechanically. The air is lightly pressurized to force it to circulate in a pattern which at its end point expels the air out from the bathrooms and kitchens, keeping odours and moisture from entering the rest of the house.
Most of the time a Passive House is warmed by heat from the sun, the body heat of the occupants, and the waste heat from the refrigerator compressor, lighting, computers, water-heating system, cooking, the fan motors in the heat exchanger. Sometimes a small split AC or heat pump unit is installed to provide a bit of additional heat if it is required, or some cooling. Rather than the usual leaky building, highly tempered with energy to make it comfortable, building to the Passive House standard creates buildings that are snug, with fresher air quality and the increased human comfort that comes when a room's temperature is consistent, from the rear wall to adjacent to the (much better constructed) windows.
Since the time of the construction of the Saskatchewan Conservation House, we as a society have become much more aware of the impact of greenhouse gases on the Earth's climate. Though we spill a lot of ink worrying about the impact of SUVs and jet planes, the contribution of greenhouse gases by the transportation sector is dwarfed by the contribution of greenhouse gases generated through the operation of buildings, which account for about 45% of all greenhouse gases, more than the transportation and industrial sectors combined. Despite this, there are comparatively few advocates for building better buildings or for retrofitting buildings.
Bitter crunchy cold, no furnace. Yet you find heat.
Saskatoon on frosty day,
Dreamy can you be, alas:
See clouds of leaky money,
And extra greenhouse gas.
The Leadership in Energy and Environmental Design (LEED) program is focused on reducing the impact of buildings, though the highest level of certification, LEED Platinum, can be attained with 30% improvement over the "normal" American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standard. Passive House certification requires an 85% improvement. Thousands of buildings have been built this way, typically at a slightly higher initial cost, that is offset by the capital savings leading from a simplification of the mechanical equipment, and the forever savings of operating a Passive House off into the future. It's the right thing to do, it's what we should be doing. In the end it will cost you less or a tiny bit more.
It seems likely that global warming will bring more difficult storms, and heightened potential for service interuptions. Conventional buildings can become difficult to inhabit within hours or a few days without electric power and other fuel inputs. A winter test without power on a Passive House near Montreal showed that it was almost impossible for the building to freeze; after a month, it barely got cool. Aim for that.
Since up to 90% of the energy used in the life of a typical building will get used after the building is occupied, the focus is on squeezing out every watt that will be needed after the building is occupied. Solar panels, recycled materials etc., the nice "green bling" don't get points, but of course we would still do some of it. Maybe you would want bling. We want to design buildings that are going to be durable, fresh and healthful, that work towards keeping the Earth habitable, that you might want to pass on to your kid.
Passive House is the future. After 2015, most new buildings in Brussels will have to be built to this standard. Allen & Lea is very interested in helping to usher in this building revolution, to build one for you.
If you are interested to learn more about Passive Houses, and the perfect storm that first created this type of building, see Passive House Past and Future by Chris Lea.
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