ACH50 Question

[dbarry14]

First here's a little background. I'm working on a multi-family residence. I'm trying to figure out how much (if any) continuos ventilation I need to provide for each apartment. In living areas I need at least .35 ACH or 15 cfm/person whichever is greater. Energy Star says that for my climate zone I am required to have infiltration of 4 ACH50 or less for these apartments. How do I convert ACH50 to a standard ACH? I guess what I'm hoping is that if 4 ACH50 ~= to .35 ACH then I won't have to provide any continuous exhaust. I can then use the natural ventilation provision per the mechanical code to prevent having to provide continuous ventilation. There will still be exhaust fans in the bathrooms as required. Any help is greatly appreciated.

 

[imok2]

Natural Air Changes per Hour (ACHnat) shall be less than or equal to .50 Air Changes per Hour
ACH 50 (ACH50), where, ACHnat = LBL Factor . ACH50 shall be determined by a blower door test
in accordance with ASTM Standard E779-87
So when you determine what the ACH50 test is then you devide by the LBL which is determined by the country zone you are talking about.