Passive House: Innovative and Affordable
Last week I had a chance to take a tour of Dwell Development’s Passive House at Columbia Station, near the Columbia City light rail station. Passive house (or Passivhaus) is a concept that I described in an article I wrote for Sustainable Industries a few years ago. Here’s what I wrote then:
Passivhaus buildings have:
- A super-insulated envelope (in our climate, perhaps an R-48 wall, R60 roof);
- High-performance triple-glazed windows (U-value .15 or lower);
- Reduction or elimination of thermal bridging;
- Super airtight construction (has to meet Air Change Rate of .6 ACH @ 50 Pascals, almost unheard of, and probably the hardest part of building a passive house);
- Heat-recovery ventilation; and
- Use of passive sources for heat gain – solar of course, but also lighting, appliances and even people in the building.
Passivhaus design takes advantage of materials to dramatically limit total energy consumption by reducing the need for heating and cooling. It’s ‘passive’ because keeping a building warm or cool doesn’t require flipping a switch or adjusting a thermostat. In other words, it’s self-regulating. The building—because of materials and design—retains heat when it’s needed most without the need to heat up cold air and move it around.
Building a Passive House is a complex undertaking and includes many custom-built and hard to find materials. The windows, for example, are pricey and have to be ordered from a manufacturer in Lithuania. You’d think that a Passive House would be very expensive—but compared to the other homes around it, the Passive House is not expensive at all.
In fact, Dwell’s product at Columbia Station ranges from the high $300,000 range to the low $500,000 range. For a dual income couple earning a combined income of $150,000 the mortgage on any of these homes—including the Passive House—would be 30 percent of their monthly income or less. And that doesn’t take into consideration the energy savings built into all of Dwell’s homes. Passive Houses typically deliver as much as 90 percent savings on energy over regular houses.