Surface penetrations in Passive House

With the Passive House house envelope being completely air-tight, any wall or roof surface penetrations become less than desirable due to a possible thermal bridging or an air leak. But that is not to say that a chimney is out of the question, for instance. With certain precautions and extra insulation, some necessary openings to the exterior can be achieved without compromising Passive House efficiency.

Sealing all points of entry

Our ventilation system required two sets of air intake and exhaust. There are two plumbing vent stacks and one chimney flue coming through the roof. And finally, there is laundry. For the latter, we really tried to go with a very efficient self-condensing unit that does not require exhaust but some well-known drawbacks (mainly the time it takes to wash and dry along with the average unit capacity) took it out of consideration. So we ended up going with a more conventional double-unit with 4” exhaust pipe to the exterior. We pack extra insulation around the in-wall portion of the laundry exhaust to keep condensation away from the walls.

In addition, there were rather small openings for electrical wiring, plumbing, and HVAC equipment. With all wall penetrations taped up tightly with SIGA® adhesive tape, the door-blowing test did not show any significant air leakages at those entry points.

Keep in mind that the number of wall penetrations will vary depending on the dwelling’s square footage, the number of ventilation units, and one’s desire to sacrifice laundry drying time for efficiency.