passive houses

One of the original Passive Houses in Darmstadt, Germany

They are the latest buzz in energy-efficient living. There are about 15,000 of them around the world with the majority in German speaking countries or Scandinavia. They are called "a revolution in building design," but what are they?

A recent article in the NY Times attempts to explain them as "...homes as get all the heat and hot water they need from the amount of energy that would be needed to run a hair dryer. Using ultrathick insulation and complex doors and windows, the architect engineers a home encased in an airtight shell, so that barely any heat escapes and barely any cold seeps in. That means a passive house can be warmed not only by the sun, but also by the heat from appliances and even from occupants’ bodies."

Still confused? Me too. Let me clarify. The whole point is for the structures to allow, or rather create, a temperature comfortable space without the use of a radiator or furnace. It's all about sustainability. The buildings are designed using passive solar building design techniques, which means:

- They are compact - about 500 square feet of living space per occupant

- Triple-pane, insulated windows are oriented towards the equator

- A wide range of thermal insulation materials are use

- Special attention is given to eliminating thermal bridges
- They're hermetically sealed (airtight)

- The walls are the same temperature of the floor, which is the same temperature as the air, which is the same in each room

Although it's credibility is considered questionable by many, Wikipedia actually offers quite a bit of info on these structures. I grabbed the following diagrams from their passive house page.

Diagram of passive solar design techniques

Thermogram showing the heat escaping a traditional building (left) versus the containment in the passive house (right)

(thnx Jonathan)