IES-VE User Forum

Hi,

I have a question about fan power calculation in IES VE which is provided by autosize run in baseline systems. Every result of fan power is much lower than fan power calculated according to section G3.1.2.9. I want to know if it is OK and if a LEED reviewers does not have problems with that. And in addition if anyone can explain to me why there is such difference between ASHRAE and IES VE fan power calculation, I would be grateful.

Thank you in advance.

Martin

I have noticed the same thing.

For a baseline system type 7 with a fan supply flowrate of 19698.96cfm and a pressure drop adjustment of 4 in. w.c., IES gives a fan power of 23.9kW.

Manually applying the ASHRAE calculation I get 35.8kW.
It is quite a significant difference!

Has anyone found the cause of this?

Are you sure you are sizing the baseline fans properly? When you build the baseline network and go to set the "System Parameters" for it, there is an input for "Baseline fan power Adj A" this is where you would input the value of the variable "A" which should be calculated using the equations in the ASHRAE guidelines.

After you run the system sizing you will have to run "Baseline fan power sizing" in the navigator which will use the variable "A" you have inputted in the system parameters to calculate the bhp for the fan.