Thursday, November 4, 2010

Understanding the Passivhaus Standard

GreenBuildingAdvisor.Com recently posted an interview with Passivhaus founder Dr. Wolfgang Feist. In Musings of an Energy Nerd, writer Martin Holladay conducts a long, in-depth interview.

The 2010 Passive House Conference starts today in Portland and runs through the 7th.

Dr. Feist said that there are five basic elements of Passivhaus, including:
● High levels of insulation
● Reduction of thermal bridges
● Attention to airtightness
● The use of “energy-gain” windows
● Heat-recovery ventilation 

There has been debate about whether or not the standard can become standard in North America, due to our climate. There are great examples of passive solar houses in places like Colorado, but there is no doubt that these are passive solar homes, as the form definitely follows function. There is a beauty in this, but the large bank of sloped southern windows, lack of windows on other sides, stone floor and solar mass walls may not be a very pleasing aesthetic to all. There are variations, though this is probably the most efficient way to build a passive solar house. The owners aesthetic might dictate that some of the elements be left out--this would just mean that they may need to depend on back-up heat more. is packed with photos and information about passive solar. Here is a typical passive solar home under construction.

To build a Passivhaus, you first must purchase the software for $225. A trial version can be viewed here.  In the software you calculate u-values, shading, energy demand, ground characteristics, etc. It's similar to the Washington State Energy Code sheets we are currently using, but much more in depth. It's a very scientific way to design a home, literally designing around the climate and elements of the site, so the design of the house grows from inside out (which is very exciting for us design nerds). 

This may result in more front-end costs for the homeowner, but the environmental benefits help us all. Usually a spec home has absolutely no context to the site or the climate, and styles are borrowed from another vernacular that make no sense in a different place. For instance, charming steep-pitched roofs in the south. The purpose of a steep pitched roof is to shed snow, and the extra heat gain from the surface area makes sense in a cooler climate. They may look great, but in a warm climate the cost (environmentally and on a utility bill) of reducing the heat gain in all those cubic feet of attic under dark shingles is ridiculous.

Not everyone can build their very own custom Passivhaus. But even small tweaks to a design to respond the climate and direction can make a big difference for the environment and your utility bill. For example, spec home developers could have different plans for different street orientations.

Last week we discussed the Living Building Challenge, a very different type of certification.

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