Passive House Ventilation

The Montessori School in Erding, near Munich, uses a very low amount of energy to heat because it is constructed to Passive House standards. Preconditioning the fresh ventilation air is one way the building achieves this high level of energy efficiency. The two ducts shown in the third picture above bring in preconditioned fresh air through earth tubes. While earth tubes use modern technology such as antimicrobial nano-silver coatings, the basic idea is nothing new. In Pecos, New Mexico the underground circular kiva ceremonial rooms used passive earth tube ventilation hundreds of years ago to provide fresh air.

Building owners should run ventilation air continuously through earth tubes to avoid mold growth. In Europe, where earth tubes are relatively common, there have not been significant problems with mold. However, many people in the United States are concerned that higher humidity—outside the Southwest, of course—could lead to mold problems if the earth tubes are not properly maintained.

Fortunately for owners in New York, earth tubes are not necessary to achieve the Passive House standard. Good insulation, air tightness, high-performance windows, and the proper orientation are enough.

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