Consider whether your HVAC system will be able to power a flush-out while maintaining temperature and humidity levels during seasonal extremes in a timely fashion, without major scheduling impacts. A total of 14,000 cubic feet of outside air must be exchanged for every square foot of floor area. The amount of outside air prescribed during a phased flush-out (0.3 CFM) may be several times greater than the normal rate required for a project’s occupancy, based on ASHRAE 62.1-2007, as required by IEQp1: Minimum IAQ Performance.
Depending on your climate and the time of year the flush-out will be completed, the energy costs of doing a flush-out could vary significantly. Estimate this early on, to help inform your chosen compliance path.
Many teams consider Option 1, but ultimately choose Option 2 for one of two practical reasons:
Scheduling the flush-out is not possible.
The building’s HVAC will not be able to maintain the required temperature and humidity levels for the duration of the flush-out. Doing so will also be energy-intensive.
If you follow the flush-out procedures required under Option 1, you will earn this credit, while if you follow the testing procedures under Option 2, you may earn the credit if your project passes the tests. This lack of certainty under Option 2 leads many project teams to pursue Option 1.
