LWR heat exchange between external surfaces of non-convex zones

asked 2016-04-12 10:44:28 -0500

BioCl
31 ●1

updated 2016-06-07 07:33:03 -0500

In a building with non-convex zones (as described in the documentation of EnergyPlus 8-4-0, in EngineeringReference/5.4.9.5 FullInteriorAndExteriorWithReflections), some surfaces are seeing each other. In the EnergyPlus Documentation about External Longwave Radiation (EngineeringReference/3.5.2 External Longwave Radiation) there is nothing about longwave radiation heat exchange between two exterior surfaces of the same building that are seeing each other. Does EnergyPlus take into account this kind of exchange ? If it does, can someone give me some details about it ?

Thanks

answered 2016-04-12 15:07:50 -0500

Archmage

7185 ●3 ●11

No, not for an outdoor exterior environment boundary condition; the model does not take that into account. They usually exchange with a blend of sky and air temperature.

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Thank your for this quick answer. To be more precise, if I'm not wrong, exterior surfaces exchange with a blend of sky and air temperature, but also with ground temperature.

Too bad EnergyPlus does not take into account LWR heat exchange between exterior surfaces, that could make EnergyPlus more suitable for district scale studies.

BioCl ( 2016-04-14 07:02:11 -0500 )edit

It is true that the surface boundary condition model includes a separate ground temperature term, but in the end there is no model for ground surface temperature and the air temperature gets used for that.

Archmage ( 2016-04-14 08:29:33 -0500 )edit

Yeah, I forget about that, it is true that "the ground surface temperature is assumed to be the same as the air temperature". But the view factor to ground is not the same than the view factor to air temperature, so in some ways the ground is considered... Or am I wrong ?

BioCl ( 2016-04-14 09:55:05 -0500 )edit

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