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

[Simge Andolsun]

Joe hi!

Thanks for your response. I had autosized the systems in both programs.
Since the loads were different, then the air flow rates ended up being
different. Based on your comments, I entered the air flow rate calculated
by eQUEST into EnergyPlus. I also added the Daylight saving time of eQUEST
into EnergyPlus. Attached is how my charts currently look like. I am also
attaching the new EnergyPlus file. Most of the problems seem to have been
resolved except the night time control. I would appreciate any suggestion
on solving this discrepancy between the two models.

Thank you very much in advance,
Best Regards,
Simge Andolsun, Ph.D.


On Thu, Feb 13, 2014 at 1:40 PM, Joe Huang <yjhuang at whiteboxtechnologies.com
> wrote:

>  (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><YJHuang at whiteboxtechnologies.com>
> Reply-To:     EnergyPlus_Support at yahoogroups.com
> To:     EnergyPlus_Support at yahoogroups.com
>
> Simge,
>
> 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 discrepancy.
>
> 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
>
>
> Joe Huang
> White Box Technologies, Inc.
> 346 Rheem Blvd., Suite 108D
> Moraga CA 94556yjhuang at whiteboxtechnologies.comhttp://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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