[Equest-users] eQUEST vs EnergyPlus: Fan Energy Consumption

Joe Huang yjhuang at whiteboxtechnologies.com
Thu Feb 13 11:40:17 PST 2014

(repost of comment on EnergyPlus_Support bulletin board in case any eQUEST-Users readers 
have other thoughts or corrections)

-------- Original Message --------
Subject:     Re: [EnergyPlus_Support] eQUEST vs EnergyPlus: Fan Energy Consumption
Date:     Thu, 13 Feb 2014 11:32:17 -0800
From:     Joe Huang <YJHuang at whiteboxtechnologies.com>
Reply-To:     EnergyPlus_Support at yahoogroups.com
To:     EnergyPlus_Support at yahoogroups.com


Looking at your plots, it seems that the eQUEST fan is simply larger by 40% or so.  Are 
you letting the programs autosize the equipment, and did you use any sizing-factors  or 
sizing-ratios in the runs?  I would just take the larger
capacity of the two runs, and use that for both runs, which should take care of the 

Other observations:
1. eQUEST CYCLE-ON-ANY seems to keep the fans on the entire hour, whereas EnergyPlus seems 
to cycling them on
     only when the HVAC is on.

2. You seem to have daylight savings in the eQUEST, but not in the EnergyPlus model.


Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 108D
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"

On 2/13/2014 9:06 AM, Simge Andolsun wrote:
> Dear EnergyPlus users,
> We have modeled a test case with exactly same inputs in eQUEST and EnergyPlus to compare 
> the results of these programs for an identical situation. This case had a PTAC system 
> with electric heating. The fan inputs were as follows in both eQUEST and EnergyPlus:
> ·0.3 inWG (74.7 Pa), 0.6 total efficiency fraction
> ·In eQUEST: Fan control is constant volume, with night time cycling
> In EnergyPlus: Fan control is constant volume (fan control schedule=1) when the fans are 
> scheduled to be on and it is cycling (fan control schedule=0) when the fans are 
> scheduled to be off. I used AvailabilityManager:NightCycle to set this control (Please 
> let me know whether there is any better way to model the same fan control condition in 
> eQUEST and EnergyPlus).
> ·California Title 24 fan availability schedules were used in both programs. These 
> schedules turn the fan off during the hours listed below:
> Weekdays: Between 8pm-5am
> Saturday: Between 3pm-5am
> Sundays and Holidays: Off all day.
> The fan energy consumption of the two programs ended up differing from each other 
> significantly. Attached are the charts that show the results of the coldest and warmest 
> days. Would you let me know what might be the reason for this difference between the two 
> programs?
> Thank you very much in advance for your help,
> Best Regards,
> S. Andolsun, Ph.D.
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