Saskatchewan

How do you choose between 3.2 ACH & 2.5 ACH?

Buildings can be constructed to meet either 3.2 air changers/hour (ACH) at 50 pascals or 2.5 ACH@50 pa (if blower door tested, but not required) in accordance to NBC (below). The details below specify the differences required in order to meet the air tightness requirements. At 3.2 ACH, the building envelope will leak (if blower door tested) 3.2 x the volume of the home through the building envelope within one hour. At 2.5 ACH, it will leak 2.5x. A 3.2 ACH built house will be leakier and have an energy penalty applied. This means that your project may require you to compensate for the additional heat/energy loss through various measures taken through performance energy modelling (increasing insulation, higher efficiency appliances, better quality windows, etc).

For projects located in Saskatchewan, we recommend running your project at 3.2 ACH if you are not familiar with the below requirements needed in order to meet 2.5 ACH. If less than 3.2 air exchanges are used in the proposed model, provide vapour barrier installation details to the authority having jurisdiction.