“Every Passive House building is a savings factory offering future security against rising energy prices.” – from the Canadian Passive House Institute website
I’ve just come back from a really exciting weekend training program in Passive House Design taught by Dr. Guido Wimmers. This renowned Austrian architect came to Whistler to create the Austria Passive House during the 2010 Winter Olympics. Now he’s spreading the word to other industry professionals about the many benefits of the Passive House. The class comprised a cross-section of architects and designers, builders, planners, and provincial policy people. Sharing ideas with my colleagues, engaging in discussion, bouncing around numbers and relating them back to practical values and needs – well, let’s just say that this stuff is my oxygen.
The course introduced us to the concepts of the Passive House, but led quickly into the nuances of highly energy-efficient buildings. We approached PH design from a systems point of view that incorporated every aspect of the house: the building envelope, the windows and doors, the mechanical systems, and more. The course was built on a vast amount of practical experience: about 30-40,000 built projects in Europe, with extensive analysis, monitoring, and refinement.
As a result, I’ve come to understand the optimal way to design an energy-efficient envelope – one that’s built on science and experience, and that isn’t prohibitively expensive. The main tool for modeling the passive building and calculating its energy use is the PHPP design software, a complex, Excel-based program that is essential in modeling these dwellings better and faster. I’m looking forward to further exploring the capacity of this incredibly useful software, and have already made some modifications to our Damn-Near Passive House project in Kaslo.
In order to earn designation as a Passive House, a design must meet some criteria: air-tightness and overall primary energy demand, including heating/cooling, hot water, plugs, etc. The primary criterion is energy-efficiency: either the total heat energy used in a year (less than 14 kW hrs/m2), or the maximum heat load for the whole house on the coldest day anticipated. Let’s translate that into practical numbers: for a 2000 square foot Passive House, the total heat energy would cost about $208 per year; on the coldest day, it would take about 1.8 kW to heat, which is just a bit more than it takes to power a hair dryer. Have I got your attention yet?
What does a Passive House look like? There’s a widespread perception that these buildings are boxy and plain – and to be fair, sometimes they are. That’s because the more the design deviates from a simple form with four corners, the greater the potential for heat loss. That said, with good design there’s lots of room for nuance, and a Passive House can assume either a modern or traditional form. You can view examples at the International Passive House database at: http://passivhausprojekte.de/index.php?lang=en#k_ .
For many people, the question of cost is uppermost. The ultimate goal of PH design is to reach an optimal point where a house no longer needs a heating system. Think about that for a second. PH design may add 5-10% to upfront building costs, but that’s offset from the very first day by saving 80-90% of energy use. BC has been known for having relatively cheap hydro, but that’s about to change. Our province also continues to buy fossil fuel energy from Alberta. Passive house design offers one of the most effective ways to reduce our carbon footprint.
There are other benefits too. One of the design criteria is “passive survivability” –what happens when the power goes out. A Passive House takes a whole week to cool from an operating temperature of 20-21°C to its stationary level of 15-16°C. It offers great thermal comfort, with no drafts, cold spots, or heat stratification anywhere. The ventilation system continuously replenishes the air supply, minimizing the levels of CO2, humidity, cooking smells, and off-gassing from furniture or carpets. Air quality is enhanced to the point where it’s possible to have an allergen-free home.
If renovating your current home, you might consider energy upgrades. Some parts of the house are hard to bring up to PH standard retroactively, especially with heat loss through the foundation or slab. Still, it’s been proven that with careful planning, energy costs can be reduced by up to 80%. Government-sponsored incentive programs seem to come and go, but it’s worthwhile to take advantage of them when you can. We hope that Canada will follow the lead of Europe, where PH is being adopted widely as the building standard at the municipal and national level.
For more information, here’s a link to some FAQs at CanPHI website: http://www.passivehouse.ca/faq/
You can also watch a great short video called “Passive house explained in 90seconds” at http://www.passivehouse.ca/videos/