[TRNSYS-users] External shading during the night

[Enertech]

Dear Marion,

Thank you for this explanation.
Given this, and in order to take into account the sky obstruction during 
the night by the shading devices, Tsky should probably be replaced by the 
external temperature when the shading devices are shut, since the shading 
devices temperature approximately matches with the external temperature. In 
that case, radiative transfer doesn't occur any more between the window and 
the sky.
With this system, I've reached a 10% decrease in heat needs, for a low 
consumption building.
Do you share this point of view?

Thanks for your help,

===========================
David Chénier
ENERTECH
F-26160 FELINES SUR RIMANDOULE
tel-fax : 04 75 90 18 54
Email : sidler at club-internet.fr
Web  : http://sidler.club.fr
================================

At 11:37 05/06/2007, you wrote:
>Dear David,
>
>The external shading device doesn't have an impact on the radiative transfer
>between the sky and the windows unless you define an additional resistance.
>The external shading acts as a thermal resistance and without define its 
>properties
>It can't be taken into account by the window model of TYPE 56.
>
>
>Best regards,
>
>Marion
>
>
>-----Ursprüngliche Nachricht-----
>Von: Enertech [mailto:sidler at club-internet.fr]
>Gesendet: Montag, 4. Juni 2007 15:23
>An: TRNSYS-users at engr.wisc.edu
>Betreff: [TRNSYS-users] External shading during the night
>
>
>Dear Trnsys Users,
>
>I'm using an external shading device (in the .bui file) during the nights
>of winter, without additional resistance, in order to evaluate the effect
>of radiative transfer between the sky and the windows during the night.
>
>It turns out that, in my simulations, external shadings have no effect. I
>obtain the same value of heat needs with or without external shadings
>during the night.
>
>However, manual calculations with radiation transfer equation tend to
>acknoledge a relevant effect of using shading devices.
>
>Could you help me with this issue ?
>
>Thanks in advance,
>Kind regards,
>
>
>===========================
>David Chénier
>ENERTECH
>F-26160 FELINES SUR RIMANDOULE
>tel-fax : 04 75 90 18 54
>Email : sidler at club-internet.fr
>Web  : http://sidler.club.fr
>================================
>
>
>
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>TRNSYS-users mailing list
>TRNSYS-users at engr.wisc.edu 
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===========================
ENERTECH
F-26160 FELINES SUR RIMANDOULE
tel-fax : 04 75 90 18 54
Email : sidler at club-internet.fr
Web  : http://sidler.club.fr
================================