After insulation is complete we typically test houses for air tightness. This is done by a blower door test. The required tightness by code is 3 ACH (or air changes per hour). We are typically targeting around 1 ACH. During this test, we typically find several “weak links” in the envelope. Often one can feel the draft around windows, at the plate or around masonry fireplaces.
Our HERs rater is locally based in Sagamore Beach Home Energy Raters. http://energycodehelp.com/
They are a 3rd party meaning they aren’t connected to the builder or architect and therefore have an independent role in evaluating the tightness of the house. They provide us with a final HERs certificate required by building code, effectively proving the home is in compliance with the current energy code.
In addition to testing air tightness, the HERs rater typically tests duct tightness. They also provide an independent visual inspection of insulation and mechanical systems. After their feedback we typically tighten up a few areas and have them test again at the final inspection.
- Area of Conditioned Space: 3,437 ft2
- Volume of Conditioned Space: 35,233 ft3
- Loss: CFM at 50pascals
- ACH 1 1/2*
*This test was done after insulation, but before drywall was installed. We found some areas that needed additional insulation and air sealing. The contractor will address these areas and another blower door test will be performed when the house is near completion. We expect the final test to be around 1 ACH.