Replies

1. 
   Trevor_Lambert | May 25, 2019 09:44am | #1

   There is no ACH50 number that will always provide adequate ventilation. It's measured at a pressure differential. No pressure, no air change. Even a very leaky house will have inadequate ventilation with still outside air.

2. 
   Matthew_Salkeld | May 25, 2019 10:51am | #2

   Thanks Trevor, I'm reading https://www.greenbuildingadvisor.com/article/revisiting-ventilation. Under 5.0ACH50 a home is deemed to require whole house ventilation.

3. 
   Jon_R | May 25, 2019 10:52am | #3

   It depends on the definition of "safe". Short term high exposure to pollutants is sometimes compensated for by later low exposure.

   Code uses 5 ACH(50).

   Removing a question after answers are provided is obnoxious.

1. 
   Matthew_Salkeld | May 27, 2019 12:33pm | #4

   Sorry for the offense Jon, I think my question was premature.

   I would like to make some posts about the serious divergence of two realities I see in my practice - code imposed air tightness and that HRVs are not being run properly or at all. It seems to rest on the antiquity of the HRV control strategy.