Passive House US

By Glenn Hooper Feb 4,2015

In July 2012 I had the opportunity to attend the first Passive House US + Hers rater training held in the US. I expected to be impressed with the reductions in energy a Passive House usually achieves, but surprisingly was more impressed with the actual construction details. The ease of construction and rather simplistic approach by which many new Passive Homes were being built lead me to believe that this will be the way all new homes will be built in the near future.

Passive House Institute US (“PHIUS”) is a spin off from Germany’s Passive Haus concept which was developed in the early 1990’s. Passive Haus built a home where there was a 60-70% reduction in overall energy and 90-95% reduction in heating and cooling.This is done by first designing the home to need very little cooling or heating, and by using windows to partially heat the home during the winter.

Passive house pays very close attention to the building shell, typically a passive house is under .6 Air changes per hour. To put that in perspective, Energy star homes Version 2 required less than 5 air changes. Getting below 3 is not as easy. Getting below 1 takes special attention to detail. Passive homes also limit thermal bridging by staggering
interior studs and exterior studs. Passive homes are also tested before sheet rocking. Most want to be able to fix issues before they are sealed up.

The most impressive detail about Passive House, generally it will use less than 100 gallons of oil, in a year. The entire homes electric usage for a year is comparable to your refrigerator and dishwasher.

Passive House also pays a lot of attention to ventilation. The standard HRV or heat recovery ventilation is not used and in its place is the more expensive ERV or Energy recovery ventilation. Besides always having fresh clean air, it is ducted to each room of the house so it also acts a distribution system. The few homes I saw in Vermont had one heat pump located in the living room. Because of the efficiency of the home and the distribution, the 1400 sq foot homes were being heated by 15,000 BTU’s. In northern Vermont, that’s impressive to say the least.