Passive House

In a recent issue of Dwell magazine, there was a home featured which was certified as a Passive House. For those of you who are not familiar with this term, it is a European system for creating and certifying energy efficient homes which has recently come to the US. As one who has studied LEED in depth and frequently lamented the inelegance of LEED for Homes, I was initially seduced by the simplicity of the Passive House system and their consistent results in performance.

A closer look makes it clear, however, why Passive House is so neat where LEED for Homes is so messy: it focuses almost entirely on one aspect of green building, the heating and cooling load. While LEED attempts to cover every relevant topic from sustainable site selection to reusing materials, Passive House is primarily concerned with making the building envelope (ext. walls, roof, windows, doors, and accompanying insulation) as efficient as possible.

While this focus has led Passive House to generate a much easier to follow program with much more consistent results, it can by no means be considered a complete guide to green building. LEED still offer the only comprehensive guide that I know of for addressing all of the many concerns of sustainability (even if it addresses each imperfectly).

That being said, Passive House is still an excellent program. They boast a measured and verified energy savings of about 90% over conventional construction, and many Passive House homes can be heated sufficiently by the waste heat of a hair dryer, or even just the body heat of the occupants. Since Buildings consume a whopping 60% of electricity consumed in this country, that kind of efficiency has a substantial and direct impact on sustainability.

The home featured in Dwell, for example, used a form of passive geo-thermal heating (as opposed to a ground source heat pump), in which the air intake ran through buried coils to be warmed without any energy consumption before it even entered the house. The temperature was maintained with an extremely efficient insulation system. This simple, elegant solution to thermal comfort can be implemented in any climate (coils are buried below the frost line) and works for both heating and cooling, because the temp. below the topsoil is constant, and conveniently a pretty comfortable 60ish degrees F. If the incoming air is that warm, it requires only the slightest additional push to reach cozy levels (hence heating with a hairdryer).

In summary, passive house offers an in depth analysis of one important aspect of green building, and in its focus provides excellent solutions. In conjunction with a more holistic approach like LEED, the result is a vastly more sustainable building.

And after all that serious stuff, here is another BB post about what may be the cutest thing that you will ever see, ever. A little tip: it gets better the more you watch it.