Passive House FAQ
Here are a few FAQ from the Passive House Canada Website: http://www.passivehousecanada.
Do Passive House buildings use solar panels, geothermal systems and wind generators to achieve their excellent energy efficiency performance?
No. The thermal performance or efficiency of a building, and the energy source or technology used supply heat or electricity, are two different things. Renewable energy systems do not affect the thermal efficiency of the house itself. In a Passive House building the primary goal is to achieve a superbly well-insulated and tightly sealed building envelope, then introduce fresh air via a very high-efficiency heat recovery ventilation system. Renewable energy technologies can be used on Passive Houses and are often installed if the budget permits.
My builder says putting more insulation into a house than the Building Code requires is uneconomic.
When you continue adding insulation to a building beyond what seems economic, there is definable level of efficiency where a full-sized furnace is no longer required because sufficient heat can be delivered to the building by other means. This allows capital cost savings to be realized on the heating and cooling system. Savings that can be put towards extra insulation and higher efficiency windows. This “definable point” is how the Passive House Standard is measured and achieved.
The Passive House Standard works in Europe but our winters are more severe. Does it work in Canada?
The Passive House approach works because it’s a pragmatic combination of applied building science and economics. Central European solutions must be modified for regions where temperatures often fall below -20 degrees C or -30 degrees C. All Passive Houses are designed using PHPP software, which allows an architect or builder to specify the combination of insulation and components required to bring any building to the required performance standard in their own climate zone. Passive House buildings have been completed in many severe climates, from central Russia to Finland, northern Minnesota, and northern Sweden.
Can you retrofit a building to the Passive House Standard?
Passive House retrofit is becoming a viable and increasingly common option in Europe, especially for low-rise apartment buildings. Canadian houses are generally built without good passive design characteristics – they often have inefficient shapes (i.e. high area to volume ratios), they’re generally not oriented towards the sun or they experience significant winter shading. They may have a lot of north-facing glass as well as serious thermal bridges, and their interior layouts may be difficult to change. Often a significant part of the value of the house may be invested in exterior brick or stonework, making re-insulation from the exterior non-viable. So, although it can be possible to dramatically cut the energy consumption of a house or building, perhaps close to Passive House levels, it may not be cost-effective to do so, depending on the state, shape, size and age of the house.
Why do you need a ventilation system in a house? Isn’t there a big energy cost to keeping those fans running?
A lot of energy is required to heat air, or cool it during summer, yet very little energy is needed to move air around via an efficient fan. Therefore in order to achieve low energy use in a building, air leakage has to be minimized, or the heating energy you pay for just ends up leaking outdoors. All Passive Houses must achieve a stringent airtightness requirement of 0.6 air changes per hour (ach) at 50 Pascals pressure. Certified Passive House ventilation units have exceptional ECM fan energy performance of no more than 0.45 Watt-hours per cubic metre of ventilation air, so the cost of running one is $50 – $70 per heating season, with much of this energy cost recovered in the form of heat.
Wouldn’t a Passive House building overheat in summer with lots of insulation and south facing glass?
One of the design requirements for any Passive House building is to ensure summer comfort. Buildings must be designed with appropriate summer shading on south-facing glazing. In areas of high summer temperatures where cooling loads predominate, e.g. southern US states, it often becomes necessary to minimize east- and west-facing glazing, as well as using spectrally selective glass to reduce summer overheating. The amount of south-facing glass, like every other building component, is determined by the designer according to client requirements and the PHPP.
Can you build large buildings to the Passive House Standard?
Yes, any type of building can be built to the Passive House standard. In Europe there are Passive House schools, office buildings, supermarkets, retail centres, gymnasiums, health clubs, and thousands of Passive House apartment units. The largest current apartment development is the Lodenareal complex in Innsbruck, Austria, which has 354 rental apartments and 128 condominiums, all built and certified to the Passive House Standard.
What’s the extra cost of building a house to the Passive House Standard? Is this a good investment for me?
The incremental cost of reaching Passive House performance depends on several factors, including the severity of the climate, the type of building and the availability of high quality building components. The cost effectiveness of doing so in any location will be affected by the local price of energy and by local building energy standards. In Canada building energy standards are lower than in many parts of Europe, and it is relatively difficult to source high quality components here, so the incremental cost of building a Passive House would typically be 10%, assuming that the builder has some experience and training in this type of construction. Are Passive Houses a good investment? Absolutely, with an 80 – 90% reduction in annual heating/cooling fuel consumption the energy savings will cancel out much of the increased up-front investment cost of increased insulation, better-quality windows and ventilation systems. Even at current Canadian energy prices the total monthly cost of owning a Passive House will be very similar to the total monthly cost of owning a conventional house. However the Passive House owner will also enjoy higher indoor air quality and comfort, and will have security against rising fuel prices in the future.
For more information on this topic and others, please contact our office:
The TLJ Team