Steve Hennigan, Credit Human’s president/CEO, was intent on making a healthy interior environment for the company’s employees. This vision, for which Hennigan set ambitious climatic goals, extended to air leakage. While the U.S. Army Corps of Engineers’ standard for airtightness is 0.25 cfm/sf @ 75 pa, project leaders set a target rate of 0.1 cfm/sf @ 75 pa. To ensure that this goal was met, Joeris undertook extensive on-site testing and later documented it in an in-depth case study. (The full deliverable is available online.
To start, curtain wall units were shop water tested prior to installation. The building, which utilized a Carlisle air and vapor barrier along with other sealant products, contained 311 envelope penetrations and utilized 9,184 brick ties, each of which was sealed with Barritech VP to avoid possible air leakage. Flashing and termination sealant were inspected to avoid “fish mouthing,” or crinkling. Basement CMU and core walls were sealed, and waterproofing and an air barrier were installed between the garage levels and upper interior floors. Cold joints on the underside of the roof were also sealed using a fire spray product.
Detailed inspection of waterproofing included water testing and selected demolition to observe water movement below finished surfaces. TSI Energy Solutions conducted tests using a PosiTest air leak tester in addition to blower and water tests carried out by others. Results found that the tops and bottoms of interior walls were the weakest points for air transmission, and floors especially, as dust and debris weren’t cleared before an acoustical sealant was installed, creating a leak, in addition to screwheads that weren’t taped and floated or covered by an air barrier. Additional small gaps were inspected and filled after installation, such as on exterior sills where fire-rated sealant was used.
How did the Credit Human building fare on the whole? Final test results revealed an extremely low amount of air leakage, meeting the goal set by Hennigan. This was paired with other sustainability features, including geothermal wells, rooftop solar installations, and rainwater catchment. Consequently, the LEED Platinum–certified facility uses 96 percent less electricity from the grid and 97 percent less municipal water than a typical building of its size. Diligent air barrier installation reduces operational expenditures for a building over its lifetime. It might be a small savings when compared with global figures, but every bit helps.