[Bldg-sim] Bldg-sim Digest, Vol 69, Issue 16

[r s]

HI,

I faced a similar situation When I was modeling perimeter versus interior
systems for an office floor plate, I saw that each zone and its loads are
isolated in the calculations and eQUEST does not factor any sort of heat
transfer between zones (adiabatic) in eQUEST. So for example if there is
curtain wall facade, the solar loads only applied to that exterior zone and
did not transfer into the interior zones. We therefore encountered issues
with oversizing for the non-exterior zones of the office space when
modeling as designed.

As I understand this appears to be case with roof loads being transferred
to plenums only and not the occupied space below as well.

I dont remember exactly how we resolved this and infact I think we took
that oversizing penalty in our model. But one of the suggestions we were
toying with was that we make an opening or model the internal wall as an
air film.

Ramya


On Wed, Aug 21, 2013 at 4:01 PM, <bldg-sim-request at lists.onebuilding.org>wrote:

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>    1. Re: [Equest-users] Roof Conduction Load (Joe Huang)
>    2. Job Posting: Senior Energy Engineer at Ecology Action
>       (Philip Boutelle)
>
>
> ---------- Forwarded message ----------
> From: Joe Huang <yjhuang at whiteboxtechnologies.com>
> To: Jeremiah Crossett <jcrossett at phasechange.com>
> Cc: "<equest-users at lists.onebuilding.org>" <
> equest-users at lists.onebuilding.org>, "Bldg-sim2 \(
> Bldg-sim at lists.onebuilding.org\)" <bldg-sim at lists.onebuilding.org>,
> Bhartendu Awasthi <bhartendu.awasthi90 at gmail.com>
> Date: Tue, 20 Aug 2013 13:04:48 -0700
> Subject: Re: [Bldg-sim] [Equest-users] Roof Conduction Load
> **
> Jeremiah,
>
> Your  question is not quite on the mark because what I've described is
> downstream from the calculation of room loads where techniques such as the
> Weighting Factor or the Heat Balance methods come into play.   Before I get
> to that issue, though, I want to point out that the "Adjust Loads"
> procedure I described is done automatically by DOE-2 and totally invisible
> to the User;  I did so only to explain why Bhartendu (the original
> poster) was not seeing any conduction loads through the ceiling.
>
> Now, back to this "Adjust Loads" procedure, there is no simulation program
> I know of that solves simultaneously for the heat flows and the zone
> temperature.  DOE-2 does it in the two-step way that others and I have just
> described. When you said "compared to the Heat Balance Method", I assume
> you're thinking of EnergyPlus.  So, how does EnergyPlus meet this problem?
> Whereas DOE-2 does one year of LOADS and then one year of SYSTEMS,
> EnergyPlus does them in the same time step, but also sequentially.
> Therefore,  EnergyPlus calculates the heat flows using the zone temperature
> from the previous time step which are then used in its HVAC simulation
> without adjustment. This should be okay when zone temperatures don't
> change, but what about at morning start-up when temperatures could change
> by 5-10 F within one hour?  I've always wondered whether that's why
> EnergyPlus gives much lower heating loads in mild California climates than
> does DOE-2?  As far as which procedure is "more realistic", I can't say.
>
> 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 8/19/2013 9:57 PM, Jeremiah Crossett wrote:
>
>  Joe, Just wondering,  given your expertise how would you compare this to
> the heat balance method.., and what do you think is more realistic?
>
>  *
> *
> *
> *
>  *Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions
> *
> *
> 120 E. Pritchard St.  | Asheboro, NC 27203  | Mobile 503-688-8951
>  www.phasechange.com
> *
>
> *
> *
> *
> *
>
>
>
> On Mon, Aug 19, 2013 at 6:14 PM, Joe Huang <
> yjhuang at whiteboxtechnologies.com> wrote:
>
>>  Just to repeat what David and Rodrigo have already sad, DOE-2 calculates
>> conduction loads in a two step process. In LOADS, a constant reference
>> temperature is specified, which DOE-2 uses to calculate the amount of heat
>> flow through the surfaces. This is the LOADS loads summarized in the LS-E
>> and LS-F reports.  In SYSTEMS, DOE-2 calculates the true temperature of the
>> zone based on the loads passed from LOADS, as well as the actions of the
>> HVAC system.  In the course of this calculation, the heat flows ("loads")
>> from LOADS are adjusted, but this is not done surface by surface, but in
>> total using the so-called "Zone Conductance" times the difference between
>> the actual zone temperature and the reference temperature used in LOADS.
>> At this point, heat flows through internal walls are also considered, using
>> the  difference between this hour's zone temperature and the previous
>> hour's zone temperature of the adjacent space, e.g., the Attic or Plenum.
>> If you are interested in this number, I believe it can be extracted in an
>> hourly report.
>>
>> In reference to Rodrigo's question, I don't see any benefit in forcing a
>> heat flow between the room and the attic by using different reference
>> temperatures.   You will simply get a constant heat flow at that
>> temperature difference throughout the simulation. In reality, attics are
>> generally colder than the room in the winter and warmer than the room in
>> the summer, so the derived heat flow with this temperature difference
>> doesn't get you any closer to reality, in my opinion.
>>
>> 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 8/19/2013 12:05 PM, David Wood wrote:
>>
>>  Hi All,
>>
>>  The LS-C report comes from the LOADS simulation portion of DOE 2.2. The
>> plenum reference temperature used in LOADS is adjusted in the SYSTEMS
>> portion of the program and the loads in the spaces adjacent to the plenum
>> are corrected
>> correspondingly.
>>
>>  Dave Wood
>>
>>
>> On Thu, Aug 8, 2013 at 8:58 AM, Rodrigo Cerqueira <
>> rodrigo.cerqueira at mra.qc.ca> wrote:
>>
>>  Hi,
>>
>> This happens because the load calculation is made with a fixed
>> temperature (see picture). All the spaces, include plenum zones, have the
>> same temperature by default (70°F). So, all roof load appears in the plenum
>> spaces. To considerate the roof load, you have to change this temperature
>> in plenum spaces and a part of roof load will appear like "internal surface
>> conduction". But I'm not sure if this is a good practice. Maybe someone
>> else has an opinion about that.
>>
>>
>>
>>
>>
>> *Rodrigo Cerqueira, *ing. jr, M.Ing.* *
>>
>> *Simulation énergétique *
>>
>>
>>
>> [image: signatureCouriel]
>>
>>
>>
>>
>>
>>
>>
>> *De :* equest-users-bounces at lists.onebuilding.org [mailto:
>> equest-users-bounces at lists.onebuilding.org] *De la part de* Bhartendu
>> Awasthi
>> *Envoyé :* 8 août 2013 06:35
>> *À :* equest-users at lists.onebuilding.org; bldg-sim at lists.onebuilding.org
>> *Objet :* [Equest-users] Roof Conduction Load
>>
>>
>>
>> Hi All,
>>
>>
>>
>> I am doing an energy simulation model in eQuest. I noticed that the load through roof conduction in LS-C is zero where as in LS-B (for plenum space) it is showing some load.
>>
>>
>>
>> As per my understanding this load should appear in LS-C also.
>>
>> Also, if I reduce the U value of the roof, the load through roof reduces and can be accounted in LS-B only (plenum space).
>>
>>
>>
>> Refer attached LS-C and LS-B reports.
>>
>> Any help will be appreciated.
>>
>>
>>
>>
>>
>> Thanks & Regards
>>
>>
>>
>> Bhartendu Awasthi
>>
>>
>> _______________________________________________
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>>
>>
>> --
>>  Regards,
>>
>> David S. Wood
>> Principal
>> Wood, Byk & Associates
>> office:    610.347.0710
>>  mobile:  610.247.1208
>>
>>
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>
>
> ---------- Forwarded message ----------
> From: Philip Boutelle <philboutelle at gmail.com>
> To: bldg-sim at lists.onebuilding.org, equest-users at lists.onebuilding.org
> Cc:
> Date: Wed, 21 Aug 2013 09:51:03 -0700
> Subject: [Bldg-sim] Job Posting: Senior Energy Engineer at Ecology Action
> Immediate opening for a full-time senior energy engineer at Ecology Action
> in Santa Cruz, CA
>
> Job description and how to apply:
> http://ecoact.iapplicants.com/ViewJob-472387.html
>
> About Ecology Action:
> Ecology Action is a leading provider of innovative marketing and
> engagement programs that overcome barriers to reducing energy use and
> achieving environmental sustainability. Ecology Action delivers programs
> statewide to serve consumers, businesses, IOUs, government agencies and
> community partners.
>
> *--*
>
> *Phil Boutelle*  |  Energy Engineer  |  Ecology Action  |  831.515.1364
> |  pboutelle at ecoact.org  |  www.ecoact.org
>
>
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