The fan calculator determines the total system fan power allotment for an HVAC system based on ASHRAE std 90.1-2007 (performance rating method only). This is required for the baseline systems in LEED v3 energy model simulations.

Another great use for this is that it can help you approximate fan power based on industry standard (whether you have a LEED building or not).

How do I use the fan calculator?

1. Enter the supply cfm of the HVAC system.
2. Select the fan filter credit in inches of water (only if you qualify for the credit in ASHRAE 90.1-2007 section 6.5.3.1.1).
3. Select the corresponding system type (definitions per ASHRAE 90.1 appendix G).
4. Click “Calculate Fan Power.”
5. The page will display the corresponding brake horsepower, motor efficiency, and the total electrical power draw from the fans in the system.

Remember, this is the total for the system and not just the supply fan (may also include a return fan, system exhaust fan, etc.)