Correctly Using ASHRAE 62.1 or International Mechanical Code (IMC) Ventilation Calculations
Calculating the ventilation rates in zones using ASHRAE 62.1 or the International Mechanical Code is a two-part process.
A common error is to set a calculation method, but not set the correct ventilation rates for each room type. While the calculation performed with the ventilation rates is exactly the same, the ventilation rates for each room type will vary depending on the reference used. You must manually update the ventilation rates to the correct values or the ventilation calculations will be wrong.
1. Set the Calculation Method​
First, set which method you are using to calculate the zone ventilation rate using the Project Info command.
Set the Ventilation Calculation Method ▾ to the code reference you are using.
The calculation that is performed for the ventilation in a zone is exactly the same in the 2009 International Mechanical Code and all versions of ASHRAE 62.1. If you are using any of those codes, it does not matter which option you select—they all calculate the same.
2. Set the Ventilation Rates​
Second, specify the correct ventilation rates in each room using the Room Project Schedule command.
For each room type used in the project, set the values in the Ventilation (OSA) section according to your code reference. The default ventilation rates will likely be incorrect.