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Marko, The reason that the "airlayer" material in the TRNBuild libraries is massless and has no thickness is that narrow air gaps (i.e. airgaps with little or no convection in them) can be assumed to provide thermal resistance in the wall. When you have a wide air gap then the convection within that airgap becomes important and you cannot correctly account for it as though it were part of the wall. What I would recommend you do is to treat that 70cm air gap as though it were one or more airnodes separated from the ambient and the conditioned space by "walls" that consist only of your polyester foil (treated as massless layers offering only a thermal resistance). You can set the convection coefficients on the inside of those two layers as computed internally by Type56. This is probably still not an ideal treatment of the situation either but in my opinion it is more correct than lumping the air gap into the wall. kind regards, David On 4/29/2015 1:58 PM, Marko Mancic
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-- *************************** David BRADLEY Principal Thermal Energy Systems Specialists, LLC 22 North Carroll Street - suite 370 Madison, WI 53703 USA P:+1.608.274.2577 F:+1.608.278.1475 d.bradley@tess-inc.com http://www.tess-inc.com http://www.trnsys.com |