How does the Passive House Standard compare to Canada's R-2000 Standard?
Canada’s R-2000 Standard was a world leader when it was introduced in 1982. R-2000 houses achieved energy savings of around 25%, compared with conventional houses. Unfortunately R-2000 received little industry or political backing and was never introduced as a mandatory part of any Canadian building code, so only a tiny percentage (i.e. below 0.1%) of new houses have been built to this standard since 1982.
The Passive House approach took careful note of credible programs like R-2000 when it was developed in the early 1990s, but it is vastly more ambitious in achieving energy savings. Energy efficiency in buildings is defined as annual energy use per unit of floor area, so it’s easy to compare different standards directly: R-2000 houses use approx. 100 kWh/m2 per year in a typical Canadian climate, while the PH Standard is just 15 kWh/m2 per year. R-2000 was the ‘state of the art’ in 1982, while the Passive House is the state of the art in 2019 and will likely remain so long into the future.
Do Passive Houses use solar panels, geothermal systems and wind generators to achieve their excellent energy efficiency performance?
No they don’t – it’s important to distinguish between the thermal performance or efficiency of a building and the energy source or technology used to heat and cool it. Solar panels (both PV and thermal), wind turbines and geothermal heat pumps are external, bolted-on (and generally expensive) renewable energy systems which do not affect the thermal efficiency of the house itself. In a Passive House the primary goal is to achieve a superbly well-insulated and tightly sealed building envelope, then introduce fresh air in winter via a very high-efficiency heat recovery ventilation system. Of course renewable technologies like solar water heaters can be used on Passive Houses and are often installed if the budget permits. In addition, many cold-climate or cool-climate Passive Houses have a small, low-tech and inexpensive geothermal system for pre-heating incoming ventilation air.
We tried passive solar houses in the 1970s and 1980s. They didn't work. How do these building practices differ?
It’s true that a few hundred passive solar houses were built in Canada and the US at this time, but their performances were often poor: they were drafty, not too comfortable, they cost far more to heat than predicted, and they frequently overheated during summer. These were prototypes, yet their designers were nevertheless correct in recognizing the great potential for solar heating even in a cold Canadian climate. The Passive House approach to construction was developed in part by careful analysis of past mistakes. It uses cutting-edge building science to design buildings of outstanding efficiency, which maximize natural on-site heating and cooling opportunities. Over the past 30 years great progress has been made in developing a better understanding of building science and performance, as well as better design tools. In addition, superior components (e.g. windows, ventilation systems) are now available. If you look in detail at an older ‘passive solar’ house it tends to be full of significant design errors, from serious thermal bridging and under-insulation in walls, floors and roofs to poor air sealing, and from over-glazing on south facades to a dramatic over-emphasis on thermal mass. Such errors and problems are not found in today’s Passive Houses.
Why are Canadian houses so much less efficient than Passive Houses?
In the broad sense all of our infrastructure, including buildings and transportation networks reflect the cultural and economic conditions in which they formed. Canadians have enjoyed decades of cheap and plentiful energy supplies, and so our buildings, vehicles and communities naturally reflect this (i.e. they are very inefficient!). Yet it’s becoming ever clearer that there are serious climate change and energy supply implications to our wasteful use of fossil fuels and electricity. Clearly, it’s time to drastically change the ways in which we use energy. The physical reason why our houses perform much less efficiently is that they’re constructed with insufficient insulation and relatively poor quality standards and components.
My builder says putting more insulation into a house than the Building Code requires is uneconomic.
Every successive inch of insulation applied to a building yields progressively fewer savings, and nobody disputes that each extra inch of insulation has the same cost as the first. He seems to have a point! Yet something surprising happens when you continue adding insulation to a building beyond what seems to be an economic level; at a definable point you reach a level of efficiency where a full-sized furnace is no longer required, because sufficient heat can be delivered to the building in winter by other means. This allows capital cost savings to be realized on the heating (and cooling) system, savings which can be put towards the extra insulation and better windows. This “definable point” happens to be the Passive House Standard.
Is it ‘economic’ for Canadian homeowners to spend thousands of dollars each year on heating fuel? How long can that go on?
I've heard straw bale houses are the best for insulation.
Researchers at Oak Ridge National Laboratories in the US have determined that 19” straw bales have a measured R-value of around R-23, or double the effective performance of a 2×6 frame wall. In addition, straw clearly has good embodied energy characteristics, as a natural, locally produced material. Straw has the further significant disadvantage that it’s subject to attack or decay from rodents, water, moulds and fungi, so it must be well sealed and kept dry throughout the life of the building, or its performance and longevity can easily be destroyed, at huge cost. In addition, ‘straw bale’ is not a standard or a construction system at all, merely a way of building a wall, and an expensive one at that. In cold Canadian climates the Passive House Standard requires far better insulation performance than can be provided by a single layer of straw bales, and Passive House design also addresses many other aspects of the building envelope in a comprehensive, scientific and verifiable manner.
Isn't the embodied (grey) energy of the materials one of the most important factors in designing a building?
No, not in terms of the lifetime environmental impact of the building. Over the past 20 years numerous US, Canadian and European studies of the overall impact of buildings have reached the same conclusion – that annual energy use is by far the largest determinant of environmental impact, amounting to between 70 and 85% of the total lifetime footprint. The materials used are important, of course, but in our severe climate their impact is heavily outweighed by the actual thermal performance of the building. Therefore if you design a building to use dramatically less heating and cooling energy, this will make the most significant reduction on overall environmental impact (this explains the emphasis on energy performance of the Passive House Standard).
Ok, so the Passive House Standard works in Europe, but our winters are much more severe. Why should it work here?
Surely Canadians should be asking themselves why they currently live in houses which have little insulation and no passive survivability? How many Canadian houses remain habitable for more than a few hours in the event of a power cut in January? The Passive House approach works because it’s a pragmatic combination of applied building science and economics. Canada’s extreme climate actually makes it a perfect fit for the Passive House approach – the extra insulation, high-performance components and air sealing work in our favour both winter and summer, and this approach works better here than in Europe!
I've heard you can't breathe in an airtight house.
Actually, air quality is lowest in a ‘conventional’ unventilated house. Given the amount of time Canadians spend indoors, we should be more concerned about indoor air quality (IAQ) than we are. Most of us are exposed indoors on a daily basis to high CO2 levels and a wide array of potentially toxic chemicals and other pollutants, including cleaners, solvents, furnishings, moulds, offgassing materials and fire retardants. In a highly efficient Passive House building air quality is maintained throughout the heating season via a whole-house ventilation system with excellent heat recovery.
There are other IAQ advantages of building to a very high level of energy performance; for example by eliminating poor building details and thermal bridging, cold spots are avoided on the interior surfaces, which in turn eliminates moisture condensation – a limiting condition for interior mould growth.
Can you retrofit a house to the Passive House Standard?
Yes you can – our new online training course features a dramatic example of a century-old New Brunswick farmhouse, where the owners retrofitted to the Passive House Standard and achieved an astonishing (and fully documented) 92% energy savings before and after the Reno. If this can be achieved affordably on a small building, in a harsh climate, it proves anything is possible!
Why do you need a ventilation system in a house? Isn't there a big energy cost to keeping those fans running?
To some it sounds plain wrong to have a ventilation unit running all winter in a house, when the houses they grew up in didn’t seem to need this. The reality is that 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. This is just physics. 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.
In terms of the cost, Certified Passive House ventilation units have exceptional fan energy performance of no more than 0.45 Watt-hours per cubic metre of ventilation air, so the cost of running one of these very high-efficiency units is pennies per day, From an energy perspective as well as an air quality perspective this is an excellent investment with extremely high payback!
If a Passive House uses over 80% less energy than a normal Canadian house, that's still not as efficient as a Zero Net Energy house, right? So why don't we just build ZNE houses?
You’re confusing efficiency with overall energy use. Zero Net Energy buildings sound like an ideal solution to the person in the street, but they have always been and will likely remain unaffordable for the average homebuyer. This is quite a deterrent! The Passive House approach, with its greatly increased insulation levels and much higher-quality windows and ventilation systems IS an affordable option for homeowners, however. CanPHI is not against the Zero Net Energy approach, but we say “the road to ZNE should lead through Passive House” – i.e. if more ZNE houses are built in Canada they should be required to reach Passive House performance levels first, in order to minimize the necessary investments in expensive renewable energy systems.
Can you open the windows in a Passive House?
Yes, of course you can open the windows. Passive Houses are simpler to live in than most other houses – there’s no need to get the furnace guy in each year, or to get the refrigerant replaced in the air conditioner.
Wouldn't a Passive House overheat in summer with lots of insulation and south facing glass?
One of the design requirements for any Passive House is to ensure summer comfort, and the PHPP software permits detailed calculations of summer cooling loads. Buildings must be designed with appropriate summer shading on exposed glazing, especially on East and West facades. 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 glazing on each facade, like every other building component, is determined by the designer according to client requirements and the PHPP.
How can a house without a furnace be comfortable in a Winnipeg winter?
Why we don’t already build much better-insulated houses, given our severe climate? How is it that we accept having just a few inches of fibreglass between our warm interior spaces and a minus-35C winter night in Winnipeg? With such minimal thermal protection it’s hardly surprising we’re a nation of furnace-huggers, who can’t quite imagine a house without one. In most parts of Canada the Passive House approach needs a wall insulation performance of between three and seven times that of a standard “R-20” 2×6 wall. Who wouldn’t prefer to be on the inside of an R-60 wall in Winnipeg, rather than an R-12 wall?
Can you build apartment units as Passive Houses?
Yes – you can design any type of building this way. Around the world there are Passive House schools, office buildings, supermarkets, retail centres, gymnasiums, health clubs – and thousands of Passive House apartment units, including some large multi-unit developments here in Canada!
If the Passive House Standard is such a good idea, then why doesn't the Governement promote it? Can I get a government grant towards building a Passive House?
Good question; for a full answer please contact the Canadian government directly. Passive House performance goes well beyond any existing program, and yet in most locations it is not currently supported, although some provinces offer substantial rebates for new houses which qualify as high-efficiency. If you think your government should support a progressive, appropriate and dynamic energy conservation policy by offering incentives to builders and owners of Passive Houses, please contact your local MP, CMHC or the Prime Minister’s office and tell them so.
If a Passive House is really a simplified house, does it mean it's easy to build?
Passive House buildings don’t look especially different from other buildings – this approach to construction is a performance standard, not a prescriptive style of building, therefore Passive House solutions will differ significantly from region to region. You can access a wealth of information on appropriate design and construction by registering on our new online Passive House training program.
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 can be minimal and it depends on many factors, including the severity of the climate, the type of building and the availability of high quality building components, while the cost-effectiveness of doing so in any location will obviously be affected by the local price of energy and by local building energy standards. Numerous studies have shown there is little or no added overall cost to building and operating a Passive House, assuming you make wise decisions on the approach. Our new online training program is designed to help you make appropriate choices.