BCA and Air Tightness using EM0017 Revision 1 How can one make sense of this mismatch?  In this article, we will discuss how the form of the building and the weather conditions that the building is in, completely discredits the ability for AC/Hr(ACH) to work on commercial buildings. The BCA requires the following infiltration rate … Continue reading EM0017 – BCA and Air Tightness