[Bldg-sim] eQuest/DOE2 instantaneous loads

Fri Oct 2 14:50:59 PDT 2009

James,

It's good to see that you're getting a lot of help in answering your
questions. I'm sorry if my original answer was too brief to explain
the situation. Here are some additional thoughts:

1. The differences between LOADS and SYSTEM loads. You can think of
LOADS loads as the heat flows into and out of the space at a user 
defined constant temperature. In SYSTEM, DOE-2 models the effect of
those heat flows, plus the actions of the HVAC system, to determine
the true temperature of the zone and the loads imposed or met by the 
HVAC system. Thus, set point changes will not affect the LOADS loads,
but occupancy changes should have an effect by changing the internal
heat gain from occupants (but not the fresh air amount which is 
considered a SYSTEM action).

2. Deriving the component loads at the SYSTEM level. This is something
I've looked into for many years. As you've mentioned in another e-mail,
component loads are available only for LOADS, since SYSTEM deals only
with the aggregated loads for the entire zone. The component loads in 
LOADS, however, are calculated at the fixed reference temperature, and
not the true zone temperature. You can make a UA-delta T adjustment of 
the LOADS loads for this difference in zone temperature, but this will
still not account for the pick-up loads in the morning, nor tell you 
what to do with those loads when the HVAC system is off.

Joe Huang
White Box Technologies
346 Rheem Blvd. Suite 108D
Moraga CA 94556
yjhuang at whiteboxtechnologies.com

James Lo wrote:
> John,
> 
> Thanks for the info, but the procedure you described IS what we have 
> been doing. The loads from the report you showed do NOT vary when 
> occupancy and set point change, hence the problem. These loads only 
> change (from LOADS described from others) when building geometry, 
> materials and other building envelope parameters change.
> 
> hopefully I am making sense...
> 
> thanks
> 
> - James
> 
> At 02:45 PM 10/2/2009, Grando, John wrote:
>> James,
>>
>> You can create an hourly report output for this and then sum the 
>> results in Excel.  Go to the "projects and site" tab, double click on 
>> the hourly report, and add a new block.  Make it look like the picture 
>> attached.  Run the model and then go to file>export hourly results.  
>> You will then have a .csv file with the hourly loads. You can also do 
>> this for each thermal zone you created.
>>
>>
>>
>> John Grando LEED AP| Mechanical Engineer
>> Phone: 212-615-3705 | Fax: 212-615-3700
>> jgrando at cosentini.com
>>
>> Cosentini Associates - A Tetra Tech Company
>> Two Pennsylvania Plaza - Third Floor - New York, NY 10121
>> www.cosentini.com
>>
>>
>>
>> -----Original Message-----
>> From: bldg-sim-bounces at lists.onebuilding.org 
>> [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of James Lo
>> Sent: Friday, October 02, 2009 3:37 PM
>> To: Jeff Haberl; Joe Huang
>> Cc: bldg-sim at lists.onebuilding.org
>> Subject: Re: [Bldg-sim] eQuest/DOE2 instantaneous loads
>>
>> Thanks Dr. Haberl and Nikola for the info, and it's clear now what the 
>> DOE2 file definitions are
>>
>> The big question remains tho:
>>
>> 1. LOADS loads are calculated based on components of the buildings 
>> (window, wall, roof, etc) and these are design loads 2. SYSTEM loads 
>> are summarized loads subjected to the HVAC system, so these are 
>> "operation" loads
>>
>> SYSTEM loads are not separate back into components, only total loads 
>> are present.
>>
>> So my questions is really whether there is a way for me to break the 
>> SYSTEM loads back into components?, ie, x% of SYSTEM cooling load for 
>> month z is from wall conduction, y% is from window radiation, etc.
>>
>> Is this even doable? hopefully I am making sense to you guys...
>>
>> thanks!
>>
>> - James
>>
>> At 01:42 PM 10/2/2009, Jeff Haberl wrote:
>> >"SYSTEMS" outputs will be labeled SV or SS.
>> >
>> >"LOADS" outputs will be labeled LV or LS, in the upper left corner of
>> >the page.
>> >
>> >"PLANT" outputs will be labeled PV or PS.
>> >
>> >Jeff
>> >
>> >
>> >8=!  8=)  :=)  8=)  ;=)  8=)  8=(  8=)  8=()  8=)  8=|  8=)  :=')  
>> 8=)8=?
>> >
>> >Jeff S. Haberl, Ph.D.,P.E., FASHRAE..............jhaberl at tamu.edu
>> >
>> >Professor............................................................Of
>> >fice
>> >Ph: 979-845-6507
>> >
>> >Department of Architecture.............................Lab
>> >Ph:979-845-6065
>> >
>> >Energy Systems Laboratory.............................FAX: 979-862-2457
>> >
>> >Texas A&M University.....................................77843-3581
>> >
>> >College Station, Texas, USA,
>> >77843..................URL:www.esl.tamu.edu
>> >
>> >8=/  8=)  :=)  8=)  ;=)  8=)  8=()  8=)  :=)  8=)  8=!  8=)  8=? 8=)8=0
>> >________________________________________
>> >From: bldg-sim-bounces at lists.onebuilding.org
>> >[bldg-sim-bounces at lists.onebuilding.org] On Behalf Of James Lo
>> >[ljameslo at gmail.com]
>> >Sent: Friday, October 02, 2009 1:35 PM
>> >To: Joe Huang
>> >Cc: bldg-sim at lists.onebuilding.org
>> >Subject: Re: [Bldg-sim] eQuest/DOE2 instantaneous loads
>> >
>> >Joe,
>> >
>> >Since we are only novice users here and only using the eQuest as our
>> >interface, I am not familiar with the DOE2 output file well enough to
>> >isolate the SYSTEM loads. (any pointers on the file definition will 
>> be great).
>> >
>> >That said, from what we can tell, the system loads (making sure I am
>> >not misunderstand you here), such as total cooling coil output, does
>> >reflect the changes we make. That said, since I am trying to separate
>> >them out into gains from walls/window, etc, I was looking into the 
>> loads side.
>> >
>> >I assume there must be some outputs from DOE2 file which eQuest is
>> >reading from which describe what I am looking for.
>> >
>> >Any additional help will be awesome.
>> >
>> >thanks everyone
>> >
>> >- James
>> >
>> >At 12:40 PM 10/2/2009, Joe Huang wrote:
>> > >James,
>> > >
>> > >There are two sets of loads in DOE-2, in both the LOADS and SYSTEMS
>> > >routines. Make sure you're looking at the SYSTEMS loads, not the
>> > >LOADS loads.
>> > >
>> > >Joe Huang
>> > >White Box Technologies, Inc.
>> > >346 Rheem Blvd. Suite 108D
>> > >Moraga CA 94556
>> > >YJHuang at whiteboxtechnologies.com
>> >
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> 
> 