PASSIVE HOUSE
Warm, quiet, healthy. Designed to last a lifetime. Shouldn't every "forever home"?
Once upon a time in the oil crisis of the late 1970's, energy-efficient homes were all the rage in North America, and new houses were built with far more insulation than they had previously (still not a lot). In the 1980's, builders attempted to make buildings also airtight, with mixed results. In 1988, a German physicist and a Swedish professor developed a construction methodology that used the sun to heat buildings, and they called it Passivhaus.
Don't want to wade through all this explanation?
Get my super-simple summary instead!
A building designed and constructed to the Passive House standard has five key features:
1. Heating is provided mostly by the sun.
2. The building envelope (the shell) is virtually airtight.
3. The building envelope also has far more insulation, and the windows have a higher insulating value.
4. Heat recovery uses the outgoing exhaust air to heat the fresh, incoming air.
5. Junctions where far more heat is lost (thermal bridges) are nearly eliminated.
None of those features is terribly exotic, and the concept would seem pretty logical to the average person. Still, this is all just random trivia - like who cares?
Before I break down the five main features a little, here is a list of SEVEN reasons why you would want to incorporate Passive House into your new house or home remodeling project:
1. A building constructed to the Passive House standard lasts two to three times as long as a conventional building. A typical, well-built house starts to fall apart after 20-25 years. A Passive House building is designed to last 50-100 years.
2. All rooms receive a constant supply of fresh, filtered air. This equates to a healthier interior environment virtually free of allergens and pollutants.
3. The tempered supply air maintains every room at a relatively constant temperature year-round. Forget having cold feet, putting on a sweater in the winter, or overheated upstairs bedrooms in the summer.
4. The total heating and cooling cost can be expected to be roughly one TENTH that of a typical house. Take your yearly heating/cooling bill; now divide it by 10.
5. A Passive House building is stunningly quiet, as the airtightness, extra insulation, and triple-glazed windows block out almost all noise from outside.
6. Every City has a limit on the size of a building on a given lot. The City of Vancouver explicitly allows a Passive House to be larger.
7. British Columbia currently offers rebates for energy-efficient construction - over $10,000 for a house (at the time of writing).
The arcane aspect of the Passive House standard is in the details of how the features are executed.
Solar Heating
The Passive part of the name Passive House relates to the use of sunlight to heat the building passively in lieu of using an active heating system that uses artificially-generated energy. Windows are strategically located and sized to take maximum advantage of the available sunlight for each location.
Insulation
This aspect is obvious to us all: extra insulation helps keep more of the heat in a building during cold weather. What you may not think about is that it also helps keep excess heat out of the building during very hot weather.
Thermal Bridges
Buildings lose huge amounts of heat at structural elements and at junctions of walls, roofs, and floors. These locations are called thermal bridges, and a Passive House building virtually eliminates them.
Airtightness
Most buildings leak a large amount of air through countless tiny holes and cracks; heated air rushes out, and cold air blows in. A sun-based heating strategy is not able to keep up even with extra insulation, but making the building airtight makes it possible.
Heat Recovery Ventilator
A Passive House building will have ventilation equipment that blows fresh air into the house in the same way a furnace does but also transfers just the heat from outgoing air to the stream of incoming air. This heat recovery warms the fresh air and reduces the energy required to heat it to a comfortable temperature.
