1. The Passive House standard comes from Germany. Can it be applied to the climate zones in Canada?
The new PHIUS + Climate Adjusted Passive Building Standard sets targets specific to our Canadian climate zones. These targets insure the energy conservation is optimized financially to the point where adding renewable technologies is practical. Our firm has 9 project certified in Canada with several more going through the certification process, and the first building to be certified in Atlantic Canada was our Hawkins House.
The idea of “super-insulated” houses began in Canada with the Saskatchewan House in 1978, but the idea fell out of favour when energy prices dropped. Continued high utility rates in Germany generated a market for ultra-efficient building envelopes, and the idea of super-insulated houses developed into Passive House. With the federal government Low Carbon Economy action plan with building efficiency as a key strategy, we are seeing a rapid uptake in Passive House. Careful design and construction have proven Passive Houses successful in our cold Canadian climate.
2. Is Passive House an experimental concept?
No. Passive House has scientific and engineering validity as well as tried-and-true practical success. There are currently more than 45,000 Passive House buildings worldwide. The oldest among them have been operating since 1991. Many Passive Houses have been monitored and their performance validated, with average overall energy consumption proved to be on target. The European and American successes serve as a great resource for Passive House design in Canada, and we take time to attend the annual Passive House conference in order to share our experiences while staying on top of the most efficient and effective materials and methods.
3. Can Passive House's air-tight construction lead to moisture or air quality problems?
This is the concern we hear most frequently. We are passionate about building science and design all our envelopes to contain appropriate air and vapor barriers, and use breathable assemblies to ensure moisture cannot be trapped inside. People are often very concerned that the very air-tight envelope of a Passive House will result in poor indoor air quality. However, the majority of moisture and mold problems in a house is due to poorly controlled air movement, and not vapor diffusion. Moisture generated inside the house is handled by a balanced mechanical ventilation system with heat recovery, which assures superior air-quality and comfort by continually exchanging the indoor air. By constantly replacing stale air, moisture is safely removed, as well as other potentially unhealthy pollutants. And yes, you can open your windows in a Passive House.
4. How does the cost of Passive House construction compare to that of standard building?
We have found that Passive House construction in Canada costs an additional 5 - 10%. Finished costs for our houses range from $180-$225 /sqft for heated space and $80-$100 /sqft for unheated space. Added insulation and high performance windows and doors increase the cost while downsized mechanical systems decrease costs. Both added insulation and smaller mechanical systems decrease operating costs both in energy and maintenance costs. In addition, rebates are often available for very high-efficiency homes. While the high quality of Passive House building components will be reflected in higher up-front costs, the life-cycle costs of owning and operating a Passive House are much lower. Our experiences have shown that the combined mortgage and utility costs are the same when comparing a new Passive House and an identical code-built home at today’s energy rates which we expect will continue to rise in the future.
5. Is a Passive House a complicated, high-tech house that is difficult to operate and maintain?
No. Passive House is focused on a very high-performance building envelope. Without any complex systems needed to generate electricity and heat, mechanical systems that are easy to operate and maintain. We try to think of the house less as a machine and more like a warm duvet.
6. Does the Passive House concept limit the design possibilities of the home?
In theory, there are no limits for design in a Passive House. In practice, the difficult climates of Canada combined with the realities of client budgets tend to favor simple, regular forms for the envelope of our houses. These designs can then be enlivened with unheated spaces: screen porches, decks and verandas, etc. Large windows are needed on the south side, with fewer small windows on the north. The majority of energy savings come from design strategies, and once the Passive House principles are considered, the particular style of a house is unlimited. Finishes and materials can be freely chosen. The future of architecture is high-performance sustainable building: we believe that building to the Passive House standard is an opportunity rather than a limitation.
7. Can the Passive House Concept be used to retrofit or remodel existing buildings?
Passive House standard can be utilized for existing buildings and has successfully been applied to retrofit projects in Europe. The air-tightness standard of the retrofit is slightly lower than the new construction standard due to existing air leaks in the building envelope. However, the cost of these projects is substantial and making the financial model more difficult for home unless it requires major renovations in other areas. Rising energy prices are likely to make Passive House retrofits more economical going forward and we certainly need to address the energy use in existing building as part of our Climate Change action plans.
8. Is a Passive House also a Zero Energy House?
The Passive House standard is focused on energy conservation. Without adding some type of renewable power generation, a Passive House will require a small amount of energy to provide heating and electricity. Because a Passive House is so efficient, it provides an excellent foundation in the move toward Net Zero Energy homes. To a high degree, it is more cost effective to save energy within the building envelope than it is to generate energy onsite. We have several passive house projects that are also net zero and off grid designs. As costs of wind, solar and other renewable technologies are reduced in the future, a well-built Passive House is ready for Zero Energy.