Our group is now at the stage where we will begin to focus some of our energy on the design process for our new homes. We have had some discussions about this, and as a whole the group knows that they want our Cohousing units to be attractive, functional, compact and energy efficient.
Our current approach for energy efficiency is to build to the Passivhaus Standard. This standard was first developed in Europe in the early 1990s, and has grown in popularity worldwide. There are now tens of thousands of homes, schools and commercial buildings that have been constructed as Passivhaus buildings.
There are five main features of all Passivhaus buildings:
- Super-insulated Envelopes
The quantity of insulation in floors, walls and roofs is much higher than in conventional construction. Insulation levels are two to three times the levels called for in our current building codes. Walls in our area of the country would typically be 20″ to 24″ thick.
- Airtight Construction
Much of the heat lost from a conventional home is the result of air leakage. Air that can move in our out of the building through cracks, gaps and improperly sealed air barriers can waste heat and cause drafts and moisture problems. A Passivhaus building will be two to three times more airtight than homes built to standards like R2000.
- High Performance Doors and Windows
Doors and windows are chosen for their high levels of air-tightness and insulation. Windows are triple-glazed with argon or krypton filled spaces between panes of glass to reduce heat loss.
- No Thermal Bridges
Thermal bridges are the construction details that have solid materials that join the inside and outside of your home. Those details allow heat to “wick” its way from the heated inside space o the cold outside. Careful details in Passivhaus construction eliminate these sources of heat loss.
- Heat Recovery Ventilation
Living in a house built to high air-tightness standards means we need to ensure proper ventilation to remove stale air and moisture; and to replace that air with fresh outside air. This is done by continuously exhausting inside air to the outside. At the same time, fresh air is continuously drawn into the home. This may seem like an energy-waster, but this process is done using a Heat Recovery Ventilator, which extracts the heat from the air we are exhausting and moves it to the cool outside air we are bringing in. Modern heat recovery ventilators can recover 90% of the heat that would normally have been wasted.
What are the Benefits?
- Low Heating Load and Operating Costs
Homes built to the Passivhaus standard are 80% to 90% more efficient than standard construction. Passivhaus homes are so efficient that they do not require a furnace, boiler or other heating system. The only heat source required to keep your home comfortable is the heat generated by you, your appliances and the sun that shines in your windows. The backup heating system for very cold weather is usually a tiny electric baseboard heater that uses about the same energy as a hair dryer.
- Eco Friendly and Sustainable
As our world grapples with the issue of climate change and fossil fuel consumption, we welcome the opportunity to be part of the solution rather than contributing to the problem.
The Passivhaus standard results in a home that is free from drafts and temperature swings.
- Excellent Air Quality
Continuous ventilation and heat recovery means that we will have much better air quality in our homes. Indoor pollutants, moisture and humidity and cooking odours are quickly removed and replaced with fresh air.
The high levels of insulation and quality windows and doors; and the high standards for fans and ventilations equipment mean that the inside space will be very quiet.
Worried about extended power failures? A house built to Passivhaus standards will remain comfortable, even if power or fuel supplies are interrupted for extended periods of time
Learn More about Passivhaus Construction