[TRNSYS-users] When I set 1st gournd floor as external catagory, what should I set these parameters ？

[David BRADLEY]

An EXTERNAL floor means that there are ambient conditions on the back 
side of the floor of your zone. With an EXTERNAL surface, you'll need to 
provide an orientation so that TRNSYS can determine how much solar is 
incident on the back (outside the zone) surface. Type56 will also assume 
that the temperature and RH of the air on the back side of the surface 
are the ambient temperature and RH provided to the model. Bear in mind 
that there is no inherent meaning to "GROUND_FLOOR." That is just a name 
assigned to a construction.

There are certainly buildings in which all or part of the bottom floor 
is above some ambient conditions (perhaps there is an open parking 
garage underneath or perhaps part of the building is cantilevered. For 
this type of floor, you'd set the "view factor to sky" to 0 because the 
back surface of the floor faces the ground and doesn't "see" the sky for 
longwave radiation exchange. Geosurf asks for the fraction of the beam 
solar radiation that makes it into the zone that strikes the floor. If 
your zone is large with relatively few windows you can set that value to 
1 thereby assuming that all the beam radiation causes sun patches on the 
floor. The surface gains on the inside and outside surfaces should 
probably be set to zero. They are a simplified way of modeling radiant 
surfaces.

As a side note and if you have not done so already, it might be a good 
idea to consult the Type56/TRNBuild documentation, which defines all of 
the fields that TRNBuild asks the user to fill in.

kind regards,

  David


On 06/28/2022 22:36, H via TRNSYS-users wrote:
>  Deal all,
>
> When I set 1st gournd floor as external catagory,  what should I set 
> these parameters ？
>
>
>
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users at lists.onebuilding.org
> http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org

-- 
***************************
David BRADLEY
Principal
Thermal Energy System Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI  53703 USA

P:+1.608.274.2577
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com
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