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

[Joe Huang]

Simge,

You might want to try (in eQUEST/DOE-2)  FAN-CONTROL = CYCLING instead of FAN-CONTROL = 
CONSTANT-VOLUME

Joe

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 1:15 PM, Simge Andolsun wrote:
> 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 
> <mailto: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>
>     <mailto:YJHuang at whiteboxtechnologies.com>
>     Reply-To: EnergyPlus_Support at yahoogroups.com <mailto:EnergyPlus_Support at yahoogroups.com>
>     To: EnergyPlus_Support at yahoogroups.com <mailto: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 94556
>     yjhuang at whiteboxtechnologies.com  <mailto:yjhuang at whiteboxtechnologies.com>
>     http://weather.whiteboxtechnologies.com  for simulation-ready weather data
>     (o)(925)388-0265  <tel:%28925%29388-0265>
>     (c)(510)928-2683  <tel:%28510%29928-2683>
>     "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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>
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