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[EnergyPlus_Support] Re: Comfort calculation (PMV)
Thank you very much Linda, Brent and Fabyo for your quick reply.
I'm using the last version 1.2.2 030. I changed the values
of "Fraction radiant" and "Work efficiency schedule". With 6% (0.06)
of work efficiency corresponding with mechanic work (M=100 W/m2)the
PMV values are even higher (average PMV=2.85)in comparison with the
values given by WinConf software (average PMV=1.40).
Besides, with air temperatures and MRT higher than around 32ºC, the
increase of mechanical work results in lower PMV. That means that
with MRT=32ºC and Ta=35ºC the PMV=4.67 when M=60 W/m2 and PMV=4.43
when M=100 W/m2. This problem was found in both EnergyPlus and
WinConf software. Did you hear about this "problem" before or still
it is possible I'm entering wrong values?
Apart from that I have been looking without success at clo values of
a mattress and a cotton sheet to evaluate comfort during the night
in the warm and humid conditions of Havana. If you could give me any
source where I can find those values I will appreciate it very much.
Abel
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Fábyo Luiz Pereira
<fluizp@y...> wrote:
> Abel,
>
> 1 - Are there any other input parameter in Energyplus which might
> affect the results of PMV?
>
> There are the "human body emissivity" and the "human body
radiant fraction",
> but it is usual consider both as constants.
>
> 2 - Is the Mean Radiant Temperature from the output the same used
> for comfort calculation in Energyplus?
>
> I suppose that this is right, but as Brent says, try to take a
look at
> "ThermalComfortMRT" report.
>
> 3 - Which value of the "Fraction radiant" is acceptable for a
> person wearing light summer clothes? I used 0.6 as in the example.
>
> E+ uses a "Fraction radiant" equal to 0.72. Searching in their
manuals, I
> concluded that this parameter is constant. You can find the
fraction radiant
> parameter in the "EngineeringDoc.pdf", searching for "Fanger
comfort Model".
> This parameter is defined as "The fraction of surface effective
for radiation",
> and is called "feff". In my view point, this parameter only
depends from the
> skin area that actually emits radiation, and don't depends on the
clothes.
> ASHRAE recomends feff=0.7 for a seated person and feff=0.73 for a
stand up
> person.
>
> 4 - Which value should be used for the "Work efficiency schedule"
> for house activities like walking about and housecleaning?
>
> I think that a work efficiency of 8% is a good value,
considering a medium
> mechanic work (M = 140 W/m2) and putting in the work efficiency
equation: mi =
> 0.04368*M + 1.943 (ASHRAE).
>
> ________________________________________________________
> Engº Fábyo Luiz Pereira
> UFRGS - Laboratório de Vapor e Refrigeração
> Rua Sarmento Leite, 425 - Sala 203 - Centro - 90050-170
> Fone / Fax: +55 51 3316-3167 / 3316-3355
> www.mecanica.ufrgs.br/lafrig
> Porto Alegre - RS - BRASIL
>
>
>
>
>
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