This blog explores changes in the energy industry from an insider’s perspective as it transitions from the old centralized utility model to the new paradigm of distributed generation.
This blog was previously called Inside the Housing Evolution and focused on energy efficient homes. Ultimately, it’s all linked. Soon, every building will have the potential to generate, store, and sell energy. Welcome to the era of the transactive grid – the greatest shift the electricity sector has seen in over 100 years!
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.
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