https://communities.bentley.com/products/building/performance/f/hevacomp-forum/110414/frequency-simulation---fresh-air-ventilation-multi-zone-air-flow-modelHi All, I am carrying out a frequency simulation calculation and want to add in an amount of fresh air to see the effect this has on overheating - either via air change rate or fresh air for occupants. I know that the methodology for this is eitheren-USTelligent Community 12https://communities.bentley.com/thread/336532?ContentTypeID=1Tue, 01 Sep 2015 10:12:52 GMT6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:4f43743a-c4c7-4a4e-8ce8-a6c358fc1905Duncan BrownHi Kevin - With regards your first query - If you choose to &quot;Use Equipment for Fresh Air Only&quot; this will turn off all other aspects of any defined plant, other than the fresh air component. If you are only wishing to consider the fresh air component then this option is fine. The addition fresh air option is separate to any considerations of plant. The option is the most straight forward and can be considered for most cases.<br /> <br /> With regards the query on fresh air, this is introduced at the outside air temperature, as defined by your weather data.<div style="clear:both;"></div>