|MarketManager » Modeling HVAC Systems|
The Outside Air that MarketManager uses in its hourly energy calculations is the greater of:
- the Outside Air % as determined by the Outside Air Schedule, the Economizer and the Min Outside Air Field in the System | Outs Air Data Form, and
- Exhaust Air
From a conservation of mass standpoint, by increasing Exhaust Air, you are reducing Return Air, and thus increasing Outside Air%.
As you cut down on Exhaust CFM, you are cutting down on Outside Air as well, which reduces the heating energy required to heat the Outside Air, which could lead to a reduction in Unmet Heating Hours.
Two additional issues arise:
- The Exhaust Fan CFM from a Zone is the sum of the Exhaust Fan CFM and Equipment Exhaust flows if any.
- Why are there Unmet Hours in the first place? Unmet Hours can occur for a number of reasons, for example because MarketManagers Design Calculations do not take into account Exhaust Air flows, while the Simulation does.
Otherwise feel free to contact our Tech Support staff at (805) 329-6565, or via email at email@example.com.