Increasing the occupants’ comfort and ability to do their job by reducing noise and drafts while also reducing utility bills.
A preliminary blower door test revealed major air leaks in the existing masonry. These gaps were not obvious from a visual inspection and would have created huge problems with water leaks, uncomfortable drafts, noise transfer, and a high risk of condensation and mold growth. Fortunately we discovered them before the drywall went up so that the contractors could patch them.
After the test, the contractor installed regular fans in the windows to create a pressure differential to reveal where the air leaks were. Sophisticated equipment is required to measure the rate of air leakage but not to simply find the leaks.
The next step after installing the mineral wool installation is to put up a vapor retarder—on the warm side—that also acts as the primary air barrier. Intello, available from 475 High Performance Building Supply in Brooklyn, is a “smart” vapor retarder that prevents moisture transfer into the wall assembly while allowing it to dry out if it becomes accidentally saturated. After the air barrier is complete, but before the drywall is up, we will conduct another blower door test to make sure that the building’s airtightness is below the Passive House retrofit standard of 1 ACH50. Finally we will install a service cavity of 1-5/8″ furring to protect the airtight membrane.
Below is a view of the building from the F train platfrom with the old plumbing supply sign painted on the brick and One World Trade Center in the background.
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and check out video of a successful blower door test from our friends at Dwell Development in Seattle.