[Equest-users] eQUEST vs EnergyPlus: Fan Energy Consumption
BHall at karpinskieng.com
Thu Feb 13 11:17:02 PST 2014
A couple other low hanging fruit to look at is what they calc for loads since they use different methods and how much the operation it is effected by the timestep.
Brendan Hall, PE, LEED AP BD+C
3135 Euclid Avenue
Cleveland, OH 44115
P 216.391.3700 Ext 3111
E bhall at karpinskieng.com
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Daniel Knapp
Sent: Thursday, February 13, 2014 2:12 PM
To: Simge Andolsun
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] eQUEST vs EnergyPlus: Fan Energy Consumption
It looks like the airflow is autosized since you are specifying static pressure and total efficiency only. Since the fans have the same static pressure and efficiency, but different peak power requirements according to the charts you are showing, they must have different peak power and thus different peak flow rates. Since the cooling demand looks higher in the eQuest case, it appears that the fans are being sized to a higher flow rate. Maybe you should try specifying the flow rate as well to see if this brings things into alignment.
Best of luck,
Daniel Knapp, PhD, P Phys, LEED® AP O+M
danielk at arborus.ca
Energy Strategies for the Built Environment www.arborus.ca
76 Chamberlain Avenue
Ottawa, ON, K1S 1V9
Phone: (613) 234-7178 ext. 113
Fax: (613) 234-0740
On Feb 13, 2014, at 12:06 PM, Simge Andolsun <simgeandolsun at gmail.com> 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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