Finally residential building codes have decided to adress the issue of duct tightness.
Now, duct tightness shall be verified through testing when all or even a part exits the building envelope. Why? Supply or return ducts leaking outside the building envelope can created pressure planes in various rooms of a building. Such planes can cause temperature & humidification differences between individual rooms. Duct leakage will make mechanical systems work harder than need be, wasting the precious heating/cooling dollar$ of your customers. We all like rooms that are all relatively in the same climate? Yes.
Unlike commercial buildings where room air circulation is tested and balanced, residential buildings are not. Duct tightness limits are a step in the right direction. 2009 IECC 403.2.2 now contains provisions for verified leakage limits. Where duct systems run outside the building envelope, the 2009 IECC(tm) provides FOUR options for compliance:
1. Post construction testing:
Leakage to outdoors shall be less than or equal to 8cfm/100sq.ft.
2. Post construction testing w/ air handler installed:
Total leakage less than or equal to 12cfm/100sq.ft.
3. Rough-in testing
Leakage to outdoors shall be less than or equal to 4cfm/100sq.ft.
4. Rough-in testing w/ air handler installed.
Total leakage less than or equal to 6cfm/100sq.ft.
RKS Energy Consulting is prepared to test your ducts and document your compliance. If your ducts leak too much, we will be there to pinpoint the defects.