[TRNSYS-users] Fwd: Re: COOLING PEAK LOAD CALCULATION

[fdominguezm]

Dear Juan,

The following paper could help you:

"Uncertainty in peak cooling load calculations"
Energy and Buildings, Volume 42, Issue 7, July 2010, Pages 1010–1018"

The paper uses the Monte Carlo method to deal with the inherent 
uncertainties that occur in peak cooling load calculations. Using this 
approach you do not need to make "hard" assumptions on the value of the 
input variables. Instead, you just propagate their uncertainties through 
the building model and get a probability distribution for the cooling 
load. With this distribution, it is easier to inform a decision based on 
the desired safety margin.

The paper does not deal with the uncertainty in the weather conditions, 
although it could be included. The easiest solution would be to repeat 
the calculations for one design day (or week) for each season or month.

I can provide you an author copy of the paper if you need it.

Best regards,

Fernando Domínguez
University of Malaga (Spain)



-------- Original Message --------
Subject: Re: [TRNSYS-users] COOLING PEAK LOAD CALCULATION
Date: Wed, 03 Oct 2012 12:06:46 -0500
 From: David BRADLEY <d.bradley at tess-inc.com>
To: JUAN FRANCISCO BELMONTE TOLEDO <JuanF.Belmonte at uclm.es>
Cc: "trnsys-users at cae.wisc.edu" <trnsys-users at cae.wisc.edu>

      Juan Francisco,
  This is a very good question to which there are as many valid 
responses
as there are responders. My feeling is that traditional methods for
sizing cooling equipment lead to very over sized equipment and the
energy inefficiency that comes with it. Traditional sizing involves a
steady-state, worst-case scenario when all the equipment is on, all the
lights are on, and all the people are in the building. Some tools also
do not account for zone adjacencies; they compute the worst case
assuming that all zones are thermally isolated from each other. There 
is
no credit for thermal mass and no credit for shading. That is obviously
going to give you the greatest possible cooling load. There are lots 
and
lots of other justifiable methods, some of which you mention. What I
have done in the past is to look at what the peak cooling load is under
a number of these methods (with normal building operation during an
average weather year, including shading, excluding shading, during an
"extreme" weather sequence of days, during a "design day" that repeats
itself. From multiple tests, you can get an idea of how sensitive the
peak cooling load is. You can then do some experiments of limiting the
available cooling power in order to see how badly you miss your target
cooling temperature. If the overshoot is small, then under sizing the
equipment a little bit will create energy savings and the comfort
penalty will not be great. With all that information, it is then
possible to do an informed sizing the cooling equipment.
  Best,
  David

On 10/3/2012 04:44, JUAN FRANCISCO BELMONTE TOLEDO wrote:

> Dear users.
>
> Any idea how to make a good cooling peak load calculation with 
> trnsys,
> in a similar way as max. heat load calculation does in trnbuild?.
>
> I mean hipothesis about Solar radiation (What values we must consider
> and where we can find them), temperature (we consider a sinusoidal
> wave shape -as EnergyPlus does- or constant value, ...).., in which
> months we must simulate (for example i´ve found many building with
> higher values in September due to the Sun is lower and they had a lot
> of windows,.. ), , tmy files should not be used because are average
> values, or yes...etc.
>
> thank you.
> Regards.
>
> _
>
> JUAN FRANCISCO BELMONTE TOLEDO
> Universidad de Castilla-La Mancha (Spain) _
>
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users at cae.wisc.edu [1]
> https://mailman.cae.wisc.edu/listinfo/trnsys-users [2]

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Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI 53703 USA

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d.bradley at tess-inc.com [3]

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http://www.trnsys.com [5]


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