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Re: [EnergyPlus_Support] Peak heating load vs total energy use





Hi Sunny,

If you are referring to heating design load, then I think it is worth checking the schedule of people, lighting and plug load on winter design day.

If those schedules are set to 0 like the example:

    For: WinterDesignDay,    !- Field 43
    Until: 24:00,0.00,       !- Field 44

Then there is no difference between these two cases in heating sizing even you set people, lighting and plug load to zero.

For Case 2 have lower AHU heating coil size,  My guess is to look at OA object - DesignSpecification:OutdoorAir, check two fields:
Outdoor Air Method
and Outdoor Air Flow per Person

In case 2, if people density is set to 0, then, the calculated design OA will be smaller. I am not 100% sure about this, but it may worth a shot.
You can also compare the design OA in HTML file for both model to confirm.

Best,
Weili




On Thursday, September 6, 2018, 11:18:26 PM EDT, my_sunny_night@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:


 

Sorry... Just people, lights, and electric equipment loads are set to zero in Case #2.



---In EnergyPlus_Support@xxxxxxxxxxxxxxx, <jim@...> wrote :

I'm missing something....
If the two files are "exactly the same", the results will be exactly the same. If the results differ, then inputs are different. What, exactly, is different between the two files?

On Wed, Sep 5, 2018 at 10:29 AM, my_sunny_night@... [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
 

Thanks Jim. Actually my files are exactly the same. I don't have any outdoor air for any of the zones on design days. But design coil load for coil heating water of the AHU in Case 2 is lower than Case 1 while design coil load of all coil heating water of the zones are exactly the same for Case 1 and Case 2. Any insight would be appreciated.


---In EnergyPlus_Support@ yahoogroups.com, <jim@...> wrote :

Dear Sunny Night,
  1. Check volume flow at the outdoor air node, e.g., "System Node Standard Density Volume Flow Rate"
  2. While you may be confident that all inputs are identical, it's easy to miss something. You might try using comparison software such as "WinMerge" or similar to line up the files side by side and review each difference.


On Sun, Sep 2, 2018 at 10:30 AM, my_sunny_night@... [EnergyPlus_Support] <EnergyPlus_Support@ yahoogroups.com> wrote:
 

With which output variable, I can check whether additional outdoor air used for ventilation in Case 1 compared to Case 2?

Another thing, all the assumptions for Case 1 and 2 are exactly the same for HVAC sizing using design day. But the design coil load for heating coil water of AHU is lower for Case 2.

Any help would be appreciated.




---In EnergyPlus_Support@ yahoogroups.com, <jim@...> wrote :

As you say, All of the lights and other electric equipment offset the need for heating, so the heating must operate more in Case 2 (when they are OFF).
Iâ??m wondering if the higher peak heating for Case 1 is due to additional outdoor air used for ventilation?


On Wed, Aug 29, 2018 at 9:01 PM my_sunny_night@... [EnergyPlus_Support] <EnergyPlus_Support@ yahoogroups.com> wrote:
 

Hello All,
I have two identical case studies with identical assumptions for everything. I just set people, lights, and electric equipment loads to zero.. Let us call this case as Case #2. For Case #1, I used default people, lights, and electric equipment assumptions.
Annual total heating energy use is higher in Case #2 than Case #1, which makes sense.
But, peak heating load in Case #2 is lower than Case #1.
Why peak load of Case #2 is lower than Case #1 while total heating energy use of Case #2 is higher than Case #1?
Thanks for your help.


--

James V Dirkes II, CEO / President
The Building Performance Team Inc.
1631 Acacia Dr, Grand Rapids, MI 49504

(alphabet soup of efforts for greater understanding: PE, BEMP, BCxP, LEED AP)

Direct / Mobile: 616.450.8653
jim@...

Website l  LinkedIn

Coffee conversation:

You are hereby authorized to make two big mistakes each year, otherwise you will never learn anything.




--

James V Dirkes II, CEO / President
The Building Performance Team Inc.
1631 Acacia Dr, Grand Rapids, MI 49504

(alphabet soup of efforts for greater understanding: PE, BEMP, BCxP, LEED AP)

Direct / Mobile: 616.450.8653
jim@...

Website l  LinkedIn

Coffee conversation:

You are hereby authorized to make two big mistakes each year, otherwise you will never learn anything.




--

James V Dirkes II, CEO / President
The Building Performance Team Inc.
1631 Acacia Dr, Grand Rapids, MI 49504

(alphabet soup of efforts for greater understanding: PE, BEMP, BCxP, LEED AP)

Direct / Mobile: 616.450.8653
jim@...

Website l  LinkedIn

Coffee conversation:

Former gang member counseling a friend about how to improve his public speaking: "You have to pepper your talk with self-defecating humor. "

Friend: "No shit."



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Posted by: Weili Xu <weilix88@xxxxxxxxx>


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