This blog follows the latest trends in high performance housing from an insider's perspective. I am the General Manager of one of Ottawa's leading homebuilders - Urbandale Construction, and it gives me a firsthand view of how the industry is changing. I've seen the barriers that builders face when trying to market new technologies and I've been working directly to overcome these barriers to bring new energy efficient designs into Urbandale homes.

December 8, 2011 7 Comments

Passive House VS Active House: Two Competing Visions for the Future of Homes

Passive House is a building standard originally developed in Germany that can reduce heating needs by an astonishing 90%. They reach this target by making the house extremely well insulated, virtually air-tight, and by orienting and designing the house to maximize passive solar gain. Although this concept has been slow to take off in North America, it’s extremely popular in Europe, with over 15,000 buildings registered to the Passive House standard.

The easiest way to make homes super-insulated and air-tight is to reduce the number of windows, especially non-south facing windows, since they don’t let in solar heat gains. So who has the most to lose with the increased popularity of Passive House homes? Window manufacturers of course! That’s why Velux, the world’s largest manufacturer of skylights, created a competing building standard called Active House as an alternative vision for energy efficient homes of the future.

The Active House building standard incorporates some of the same concepts of Passive House, such as insulation, air-tightness and optimal solar exposure. However, it also promotes increased natural light and ventilation through the use of, you guessed it, Velux skylights and windows. Their products feature automated controls to bring in fresh air when needed, as well as automated blinds and exterior awnings to control shading. Due to the additional windows, Active Houses cannot be as well insulated as Passive Houses and typically require renewable energy systems, such as solar water heaters and/or geothermal heat pumps, to reach similar energy targets.

Which approach is better? Well, if you’re asking me which house I would rather live in, the answer is simple, Active House hands down. While the Passive House has a singular focus on energy efficiency, the Active House expands the focus to quality of life issues, such as indoor air quality, fresh air, and natural sunlight. A cave in a mountain with one south facing window and a toaster as a heater could essentially pass as a Passive House. The flip side of course is that a Passive House could be built much more economically than an Active House. The need for expensive cutting-edge technology in an Active House makes it far too expensive for most homeowners. To date, Active Houses have primarily been built as show-homes or demonstration homes to prove the concept. Most people cannot afford this type of home until the price of the technologies used decline.

So, will Urbandale build homes to either of these standards in the future? Honestly, it’s not likely. In my opinion, neither standard is appropriate for our market. The central criteria for the Passive House standard is that a house cannot use more than 15 kWh/m2/year in heating. This benchmark was developed with Germany’s climate in mind and is very difficult to achieve with Canada’s much colder winters. For example, our walls have R-22 insulation, and to reach the Passive House standard R-60 is required, making the walls almost three times thicker. Thicker walls mean less floor space, and with today’s high land prices I think few people would be willing to make this tradeoff. On top of this, both the Passive House and Active House rely heavily on solar orientation, meaning the house must be set south facing on the lot to maximize free heating energy from the sun. This approach works very well for custom builders who build a few homes on empty lots in the country. When you are building hundreds of homes a year and developing full subdivisions, it is next to impossible to ensure that every home is optimized for Southern sun exposure.

Urbandale’s approach is to design well insulated and air-tight homes with high efficiency heating and ventilation equipment that use less energy regardless of how the home is oriented. We are mindful that there is a limit to what purchasers can afford to spend on even the most energy efficient homes, and have a package of efficiency upgrades that are both effective and affordable. The Passive House and Active House standards have their niches and may be appropriate for other builders in different markets. Any approach that reduces the amount of energy used in new homes is beneficial, regardless of how it’s branded or packaged.

Posted by Matthew

7 Responses to "Passive House VS Active House: Two Competing Visions for the Future of Homes"

  1. Hibbs Homes says:

    One of the main goals for the active house usa project is to develop a prototype that works for mixed climate, which may make that top-runner a more feasible option for Urbandale in the future.

  2. Matthew Sachs says:

    I’m not familiar with the Active House USA project, but it would be great to see more of these houses built in North America. By the way, I checked out your website. You build some very beautiful custom homes.

  3. Hans Eich says:

    Hi Matthew,

    great write up, I think you’ve got some of the facts wrong about the passive house though. The passive house starts out with the ideal living conditions/requirements (fresh air, ideal relative humidity and very little temperature differences/variations) and then sees how it can be accomplished _affordably_ at a drastic reduction of the energy that this requires. The active house is thus (ideally) more of a logic continuation of the passive house, adding some automation and alternative energy generation (similar to a net zero or energy plus house).

    The main shift that needs to happen though is a rethinking of wwhat a subdivision really is and what it needs to provide to its inhabitants. Passive house subdivisions (with cleverly designed row houses) are actually easier to realize than single PH family dwellings.

    Some active houses are just a standard houses packed full of automation, but that’s generally not the idea and ruins it for us all, passive or active. I’d love to chat.

    Hans 905-321-3905

  4. Matthew Sachs says:

    Hi Hans,
    Your point about rethinking subdivisions is well taken. One of the challenges that I’ve faced is that traditional subdivisions are not laid out well for solar orientation, so you have to design the house for the worst case scenario which adds to costs. I could imagine a developer taking a small project and designing it all for passive solar, but I couldn’t see this approach working on a large scale because it isn’t feasible for every house to have proper solar orientation. There are also legitimate reasons why subdivisions are built with curved streets instead of as a grid, and going against the grain on that raises some new market challenges.
    I’m glad to see you out there promoting passive houses though! Anything that raises awareness for energy efficient building is a positive step.
    Matthew

  5. sara says:

    Hi Matthew,
    thanks a lot for the interesting article. I am very interested in the subject Active vs Passive houses and I was wondering if you know where one could find some estimates of the costs relative to these two building standards.
    Thanks!

  6. Matthew Sachs says:

    Hi Sara,
    Unfortunately I don’t know where you can find specific cost information. Some Passive House resources claim zero incremental cost, but I don’t believe them. Perhaps it’s possible if you sacrifice all your non-South facing windows! There really is a lot of variability in costs because there are many different ways to design a home to achieve this standard. The Active Houses that I have seen are all multi-million dollar (Euro??) demonstration homes. Again, it’s hard to look at just the incremental cost because there is no baseline house that they are comparing to.
    Matthew

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ABOUT THE AUTHOR:

Matthew Sachs

B. Eng. LEED AP

  • General Manager of Urbandale Construction since May 2008
  • Vice-Chair R-2000 Renewal Committee
  • Member of Energy Star Technical Advisory Committee
  • Greater Ottawa Homebuilders Green Committee
  • Recipient of Canadian Homebuilder’s Association 2009 R-2000 Builder of the Year Award
  • Participant in Natural Resources Canada’s Technology Roadmap for Sustainable Housing
  • Energy Consultant with Marbek Resource Consultants (Feb 2002 – May 2006)

ABOUT URBANDALE CONSTRUCTION:

Ottawa's Quality Homebuilder for 30 Years. Building R-2000 and Energy Star Homes in Kanata Lakes, Riverside South, & Bridlewood in Ottawa, and in eQuinelle in Kemptville. For more information on Urbandale Construction, please visit www.urbandale.com.