Prospect Architecture is currently finishing the construction of one of the first Passive Houses in NYC (see NYPH project directory for other projects under construction). Since the project is a gut rehab of a landmarked brownstone, all the insulation and airsealing had to be accomplished on the interior of the brick shell. Getting the building up to Passive House air tightness standards (0.6 Air Changes per Hour at 50 Pascal pressure) has proven to be a challenge.
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There are multiple ways to do find leaks once you start sucking into the house at that pressure. The larger leaks can be detected by running your hands along window and wall edges. Smaller ones can be found by using a lighter on the inside of wall and corners, if the flame starts to bend/flicker, a leak has been detected. Lastly a commercial smoke machine (think disco) is used on the outside of the house to produce a large smoke cloud. The pressure in the house created by the blowerdoor, will suck the smoke into the house through smallest cracks. Thus where smoke appears, a crack is present and can be detected. During the first two hours, the entire crew walked all 5 floors of the house and using these methods marked all the leaks with blue painters tape.
Different crews started to fix the found leaks be performing specific tasks throughout the house. Large holes, for example the newly installed exhaust for the (back up) instant hot water heater, had to be sealed with spray foam. The plumber had made a big hole in the wall to run his pipes.
Most leaks were much smaller, however they all add up so were addressed as well. The original wainscoting and window frames had many leaks among the edges of the original woodwork. These were all caulked in a matching color. Airtight cover plates were put on all electrical outlets. Duct-work terminations were sealed to the structure with mastic. And a variety of other leaks were addressed (hatch, windows) or marked to be fixed in the next weeks.
After pizza lunch, some additional sealing was completed and it was determined that all spray foam that had been applied earlier in the day was sufficiently cured, the blowerdoor test was performed for the second time. As it was know that the custom build airtight doors in the basement were missing thresholds and would thus leaks significant amounts of air, the airchanges were not up to Passive House standards yet, but a 15% improvement had been made during this one day. It is the expectation that once the few remaining big leaks are addressed that the house will meet the standard and that this event had provided a big push to get the building that tight.
