Cambridge Day at the dasHAUS Exhibit
I am neither an architect nor a contractor, so forgive me if I misunderstand any of the passive house details—but please also correct me!
I spent this morning at MIT, for the dasHAUS exhibit’s Cambridge Day events. Presented by the German American Chamber of Commerce, dasHAUS is a traveling tour demonstrating technologies used in passive house design, which Germany is known worldwide for. If you’re not familiar with the passive house standard (which I really wasn’t before this), at heart it’s a super-tight building envelope that requires up to 95% less energy to heat than a normal design (38.1 kBtu/sf/yr, to be precise, compared to the national average of 65). In order to do this, it uses innovative insulation, an energy-recovery ventilation system, and windows with as little heat loss as possible.
The dasHAUS pavilion is not a full house, but a single airtight room with examples of different kinds of insulation, windows, and solar panels that can be used in passive house design. It’s based on Germany’s winning entries in the 2007 and 2009 Solar Decathlon, a college competition sponsored by the U.S. Department of Energy.
Possible components of the passive house design include:
- Exterior Insulating Finishing System (EIFS) - This is a continuous insulating system of rigid polystyrene, with a layer of thermal insulating plaster over it that looks vaguely pockmarked, increasing the surface area.
- Vacuum-Insulated Panels (VIPS) - These are rigid vacuum cores enclosed by reflective foil, with an amazing R value of 30, and just an inch wide. (Compare to rigid polystyrene’s R value of 5 and fiberglass’s 3.5.) The only drawback: if it’s punctured, the vacuum is destroyed, and it’s no longer super insulating.
- Heat-recovery ventilation (HRV) - This acts as both climate control and mechanical ventilation. Ducts with colder outside air and warmer inside air pass by each other over an aluminum membrane, bringing the outside air up to temperature. This keeps the house a constant temperature (stabilizing at 59 degrees F in northern European winters) and prevents moisture and mold issues. A heating coil can be added to this to further warm the incoming air.
- Triple-paned argon-filled windows with low-e coating - The argon 90 is a better insulator than regular air, and the two cavities double its insulation. The low-emissivity (metal!) coating reflects infrared light (or, as we know it, heat).
There were lots of other energy-saving details, including thin solar panels on the louvered blinds—too many to go into here. But be sure to read through the self-guided tour for more info. And I’ll be back later this week with more posts about the presentations at the legislative breakfast and green residential building panels.