1. How does the Passive House Standard compare to Canada’s R-2000 Standard?
2. Do Passive Houses use solar panels, geothermal systems and wind generators to achieve their excellent energy efficiency performance?
3. We tried passive solar houses in the 1970s and 1980s, and they didn’t work: didn’t you hear about that?
4. Why are our Canadian houses so much less efficient than Passive Houses?
5. My builder says putting more insulation into a house than the Building Code requires is uneconomic.
6. I’ve heard straw bale houses are the best for insulation.
7. Isn’t the embodied (grey) energy of the materials one of the most important factors in designing a building? 
8. OK, so the Passive House Standard works in Europe, but our winters are much more severe – why should it work here?
9. I’ve heard you can’t breathe in an airtight house.
10. Can you retrofit a house to the Passive House Standard?
11. Why do you need a ventilation system in a house? Isn’t there a big energy cost to keeping those fans running?
12. 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?
13. Can you open the windows in a Passive House?
14. Wouldn’t a Passive House overheat in summer with lots of insulation and south facing glass?
15. How can a house without a furnace be comfortable in a Winnipeg winter?
16. Can you build apartment units as Passive Houses?  
17. If the Passive House Standard is such a good idea, why doesn’t the Government promote it? Can I get a government grant towards building one?
18. So a Passive House is really a simplified house? Does that mean it’s easy to build?
19. What’s the extra cost of building a house to the Passive House Standard? Is this a good investment for me?

 

1. “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. Compliant houses had to be modeled using a software program (HOT2000 or H2K) to calculate annual energy use, and they also had to have a heat recovery ventilation system as well as a minimum level of airtightness, which was verified by a blower door test.     R-2000 houses achieved energy savings of 25 - 30%, 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. In the past 5 years the Energy Star performance standard has been promoted in Canada in place of    R-2000 since it has less stringent airtightness requirements and is therefore easier to achieve. So you could say that our leading-edge building efficiency standard has actually dropped over the past quarter century. 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 2011 and will likely remain so into the future.

2. “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), windmills 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.        

3. “We tried passive solar houses in the 1970s and 1980s, and they didn’t work: didn’t you hear about that?”

It’s true that thousands of 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.

4. “Why are our Canadian houses so much less efficient than Passive Houses?”

There are several answers to this question; 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 not very efficient). 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 update 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. Standard design practice is to insulate only modestly, as buildings codes allow, theninstall a large furnace (and often an air conditioner).Yet this is a design approach from the 20th century, not the carbon-conscious 21st! The Passive House approach has shown that you don’t need a conventional furnace or boiler to achieve high levels of comfort and indoor air quality in any building, if you design that building correctly in the first place. 

5. “My builder says putting more insulation into a house than the Building Code requires is uneconomic”.

Your builder is correct in pointing out that 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. If you calculate energy savings over any the lifetime of the building then your builder’s logic turns out to be incorrect, since the net extra capital costs are heavily outweighed by the net fuel savings (and that’s without taking into account possible dramatic rises in fuel prices in the future). The bottom line is that it’s uneconomic for Canadian homeowners to spend thousands of dollars each year on heating fuel.

6. “I’ve heard straw bale houses are the best for insulation”

There’s no doubt that a straw bale wall performs much better than a conventional one – a standard “R-20” 2x6 wall actually has a real R-value of about R-12, due to thermal bridging through the wood frame. 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 that of the 2x6 frame wall. In addition, straw clearly has good embodied energy characteristics, as a natural, locally produced material. However, some proponents of straw bale construction greatly exaggerate its performance, often quoting discredited and unverified research data, and suggesting that bales have insulation levels of R-50 or even R-60. Straw is not such a good insulator, however, and it has the further significant disadvantage that it is 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 to the homeowner. In addition, ‘straw bale’ is not a standard or a construction system at all, merely a way of building a wall, and often an expensive one at that. In cold Canadian climates the Passive House Standard requires far more insulation than can be provided by a single layer of straw bales.

7. “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). The materials selected for interior finishing are critical to indoor air quality, however, and in any house should always be chosen to minimize offgassing. Potentially toxic glue-based products (e.g. chipboard), which can offgas formaldehyde and other undesirable products, should be avoided wherever possible.  Indoor air quality can also be improved by choosing low-VOC paints, and by selecting benign finishing materials such as tile, solid wood and natural fibre or wool rugs.

8. “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? And who can be confident today that power and fuel will flow in all regions without interruption over the next 20 years, let alone beyond that time? The Passive House approach works because it’s a pragmatic combination of applied building science and economics. Typical central European solutions (i.e. based on design temperatures of only -15C) must be modified for regions where temperatures often fall below -20C or -30C. All Passive Houses are designed using the PHPP software package, 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 Houses are now being built in many severe climates, from central Russia to Finland, northern Minnesota, northern Norway and Sweden. Canada’s extreme climate actually makes it a perfect fit for the Passive House approach!

9. “I’ve heard you can’t breathe in an airtight house”.

Given the amount of time Canadians spend indoors, we should probably be more concerned about indoor air quality (IAQ) than we are. Most of us are exposed indoors on a daily basis to a wide array of potentially toxic chemicals and other pollutants, including cleaners, solvents, furnishings, moulds, offgassing materials and fire retardants. Poor IAQ is very likely implicated in the increasing levels of asthma, allergies and respiratory problems being experienced amongst Canadians of all age groups. In order to achieve high levels of energy efficiency in any building it’s imperative to make that building as airtight as possible, yet this should clearly not happen at the cost of sacrificing air quality! In an efficient building air quality is maintained throughout the heating season via a whole-house ventilation system with good heat recovery.  Therefore all houses which are certified to higher efficency standards, including R-2000 and Energy Star houses, will typically have higher levels of indoor air quality than houses without ventilation systems. This is also true of Passive Houses, which are 3 – 5 times more airtight than levels defined in the R-2000/Energy Star programs. 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.

10. “Can you retrofit a house to the Passive House Standard?”

That’s a good question. Passive House retrofit is becoming a viable and increasingly common option in Europe, especially for low-rise apartment buildings, and in that part of the world a strong market has emerged for the supply of the necessary very-high-performance building components such as windows, doors and ventilation systems. It’s been shown in Europe that all major retrofits should use such high quality (Passive House Certified) components, because the chance to significantly retrofit a building is a rare opportunity, generally affordable only every 50 years or so. 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.

11. “Why do you need a ventilation system in a house? Isn’t there a big energy cost to keeping those fans running?”

To some people 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. 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 (the R-2000 standard is 1.5 ach). In terms of the cost, 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 of these very high-efficiency units is $50 - $70 per heating season, depending on your electricity price, with much of this energy cost recovered in the form of heat. Therefore from an energy perspective as well as an air quality perspective this is an excellent investment with extremely high payback!

12. “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 (see Q.1). No ZNE house yet built in Canada likely comes near the energy efficiency performance of a Certified Passive House, as measured in terms of annual heating energy per square foot, because to date none (as far as we know) have been designed using Passive House tools, solutions or components. ZNE 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. Specifically to demonstrate the cost-effectiveness of this approach, several Passive Houses have been built in the U.S. since 2006 on social housing budgets! (contact PHIUS for details of these projects). The bottom line; for the same incremental investment in a single ZNE house it is  likelypossible to upgrade 5 or more similar-sized houses to the Passive House Standard. From a social perspective this would obviously yield a far better solution to our growing energy and climate problems. CanPHI is not against the Zero Net Energy approach, but we feel that “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.

13. “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. 

14. “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 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.

15. “How can a house without a furnace be comfortable in a Winnipeg winter?”

Perhaps a more interesting question is to turn this around and ask why we don’t already build much better-insulated houses, given our severe climate? How is it that we’ve come to accept having just a few inches of fibreglass between our warm interior spaces and a minus-33C winter night in Winnipeg? Given this minimal thermal protection it’s hardly surprising that 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 will require a wall insulation performance of between three and seven times that of a standard “R-20” 2x6 wall (effectively an R-12 wall due to thermal bridging through framing members, a value which degrades over time). Who wouldn’t prefer to be on the inside of an R-60 wall in Winnipeg, rather than an R-12 wall? 

16. “Can you build apartment units as Passive Houses?”  

Yes – you can design any type of building this way. 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.

17. “If the Passive House Standard is such a good idea, why doesn’t the Government promote it? Can I get a government grant towards building a Passive House?”

Good question; for a full answer you would have to contact the Canadian government directly, and we would encourage you to do so. Although you can get a grant under the federal Energuide program to assist in energy-saving renovations, Passive House performance goes well beyond any existing program, and yet it is not currently supported. It seems you can get some assistance in saving 5% of your energy costs, but not for saving 80%. Some provinces offer substantial rebates for new houses which qualify as high-efficiency e.g. Alberta presently offers a $10k grant for achieving the ERS 86 rating, which is well below the performance of a Passive House. 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.

18. “So a Passive House is really a simplified house? Does that mean it’s easy to build?”

As you can see from photos on this website, 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. Each country and indeed each region has its own construction traditions, architectural styles and local materials, as well as specific climate conditions. Therefore Passive House solutions will differ significantly from region to region. In Canada we have yet to clearly define the best ways to build to this standard, a situation which offers rich challenges for any architect, builder or designer who wants to work on truly sustainable buildings.  Although all Passive Houses have non-complex shapes and simplified mechanical systems, this apparent simplicity conceals a wealth of refined architectural/engineering planning and detailing throughout the building envelope. Consequently Passive House design requires specialized professional training and experience, even for the most experienced architect or builder. It’s safe to say that not a single building envelope detail in the current Canadian Building Code is thermally adequate to attain Passive House performance – so our current challenge is to define workable and affordable building solutions which meet these demanding criteria. CanPHI is working to develop viable, affordable construction solutions for Passive House projects in Canada, and we many of these solutions are now outlined in ourweek-long training courses in Passive House design and construction.

19. What’s the extra cost of building a house to the Passive House Standard? Is this a good investment for me?

This is another good question: since there are now over 20,000 Passive House units in Europe and elsewhere, much attention has been focused in recent years on assessing the cost-effectiveness of building to this advanced standard. 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, 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. In Europe the incremental cost of building Passive Houses continues to drop, as fuel prices and building energy standards rise, and as Passive House-quality building components become more and more mainstream, and therefore cheaper. For an apartment building the incremental cost for Passive House is around 3 – 5%, while for single detached houses in northern Europe the extra cost is typically higher, between 6 – 9%. 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? Yes, 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.