Toiture plate terrasse

[Mathieu.nicolay]

Bonjour,

Voilà je suis actuellement entrain de calculer une toiture terrasse et j'aurais voulu savoir si on devais cocher le bilan explicite de rayonnement ??

D'avance merci pour votre réponse

[Christian Bludau]

Dear Mathieu,

I´m working on a model about simulating a roof terrace in hygrothermal building software. A first idea, which is also using a reduction of the absorptivity and emissivity is published here, but at the moment thats only available in German:
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Bludau, Ch., Kölsch, Ph.: Verschattung von Holzflachdächern - Holz-Flachdächer: Neue Forschungsergebnisse zu Dachterrassen und Verschattung durch PV-Module. 5. Internationaler Holz[Bau]Physik-Kongress 20.–21.03.2014, Leipzig
http://www.hoki.ibp.fraunhofer.de/ibp/p ... Bludau.pdf
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For the calculation I did not model the terrace itself, outside i started with the roofing felt. For modelling the shading I reduced the existing absorption value of the wooden surface the following way:
shaded absorption = absorption of roofing felt * 0,6
and
shaded emission = unchanged

So for a grayed wood (bankirai) that would be:
abs_shaded = 0,74 * 0,6 = 0,44
em_shaded = 0,9

In this calculations you should use the explicit radiation balance in WUFI.

Christian