[Bldg-sim] Fan Power calculations in ASHRAE User Manual

[Nick Caton]

Hi Ashraf,

I'm not sure about 2004, but the 2007 users manual includes an example showing how to "back out" fan energy from a fan-inclusive efficiency rating.

I will be sharing a guide of sorts in the near future touching on this topic, with eQuest/DOE2 procedures defined explicitly.  Keep your eyes open for that! 

For now, let me offer an extra caution to your assertion regarding "fan power should be broken out at ARI conditions:" in the case of proposed systems, I'd agree that fan power entered may be entered as calculated (or ideally, documented) at ARI testing conditions.  In the case of baseline systems however, 90.1 is very explicit in setting a procedure independent of the prescribed efficiency to determine fan power for the system.  I'm pretty sure that calculated quantity (Pfan) takes precedence.

~ Nick

Ashraf Khan <ashraf at mecsd.com> wrote:

Recently Fan power calculations topic have discussed. I have a question
regarding the breaking power in to components.

 

According to Section G3.1.2.1 requires that “where efficiency ratings, such
as EER and COP, include fan energy, the descriptor shall be broken down into
its components so that supply fan energy can be modeled separately.”

Since the efficiency ratings are calculated at ARI‐rated conditions, the
fans should also be broken out at ARI‐rated conditions.

 

Kindly guide me where can I find calculations in ASHRAE 90.1-2004 User’s
Manual showing that the calculation has been performed at ARI rated
conditions or any other reference.

 

Regards,

Ashraf