[Bldg-sim] eQuest/DOE2 instantaneous loads

[Joe Huang]

Erik,

I don't agree with your assumption that going to a heat balance model
will "make life easier" for James' needs. From my experience, getting
the "component loads" from EnergyPlus is even more difficult than with
DOE-2.  About 8 years ago, there was a DOE project that tried to extract
component loads from EnergyPlus that found the task quite complicated
and convoluted.

In the final analysis, a "component load" is an abstraction,
since the HVAC system is responding to zone-level heat gains or losses
that have built up over many hours.  For example, when the air
conditioner kicks
on in the midmorning, is that "load" due to the solar through the windows,
the lights that came on, or the fresh air supplied over the past three
hours?
On the flip side, when the heating comes on at night in the Fall, is that
"load" attributable only to the cumulative envelope heat losses and how
should it be offset by solar heat gain and internal loads built up during
the day?

These are bookkeeping problems that extend beyond simply switching to
a heat balance model.

Joe Huang
White Box Technologies
346 Rheem Blvd. Suite 108D
Moraga CA 94556


Erik Olsen wrote:
>   James, this is a good illustration of the limitations of DOE2.  The 
> input won't be as easy, but life may be easier (and more accurate) in 
> this case if you switch to a simulation engine that includes a true heat 
> balance model (EnergyPlus, TRNSYS, ESP-r).  These are more frequently 
> used for investigations of dynamic building physics.
> 
> Regards,
> Erik
> 
> Erik Olsen, PE
> 212 219 2255 | olsen at transsolar.com <mailto:olsen at transsolar.com>
> Transsolar Inc. | 134 Spring St. Suite 601 | New York, NY 10012
> 
> Transsolar Climate Engineering
> Technical consulting for energy efficiency and environmental quality in 
> buildings
> New York - Stuttgart - Munich
> 
> 
> Joe Huang wrote:
>> <div class="moz-text-flowed" style="font-family: -moz-fixed">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 
>> <mailto: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 <mailto:jgrando at cosentini.com>
>>>>
>>>> Cosentini Associates - A Tetra Tech Company
>>>> Two Pennsylvania Plaza - Third Floor - New York, NY 10121
>>>> www.cosentini.com <http://www.cosentini.com>
>>>>
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: bldg-sim-bounces at lists.onebuilding.org 
>>>> <mailto: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 
>>>> <mailto: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 
>>>> <mailto: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 
>>>> <mailto:bldg-sim-bounces at lists.onebuilding.org>
>>>> >[bldg-sim-bounces at lists.onebuilding.org 
>>>> <mailto:bldg-sim-bounces at lists.onebuilding.org>] On Behalf Of James Lo
>>>> >[ljameslo at gmail.com <mailto:ljameslo at gmail.com>]
>>>> >Sent: Friday, October 02, 2009 1:35 PM
>>>> >To: Joe Huang
>>>> >Cc: bldg-sim at lists.onebuilding.org 
>>>> <mailto: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 
>>>> <mailto:YJHuang at whiteboxtechnologies.com>
>>>> >
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>>>
>>>
>>
>> </div>
>>
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