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Re: [TRNSYS-users] solar absorptance of walls



Wirich,
If you are using Trnsys17 then there is almost certainly an automatic connection of solar radiation between the weather data reader and the building because in TRNBuild the default selection is that those connections will be made for you.

I would guess that the difference lies in how you have treated the floor of your zone. If you created a BOUNDARY wall for your floor then Type56 is expecting you will provide a temperature on the back side of the floor (i.e. the interface between the floor and the soil). If you did not make a connection to the boundary temperature Type56 input then it is probably set to a constant value of 0 C, which would keep your zone temperature quite low throughout the year.
Regards,
 David


On 8/28/2014 03:30, FREPPEL Wirich wrote:
Hello everyone,

I'm running some tests in order to compare TRNSYS to another software, which is Energy+.

My model is simple, a 3 meters long cube, with the same composition for all the faces, without windows. What I did in first place, was to create a new multizone project using an idf file created from sketch up. Then I runned the simulation in order to observe the evolution of the air temperature inside the box. Comparing it to Energy+ results, I noticed that in summer, the temperature is far below those of Energy+. So I looked at the connections in simulation studio to see if there was a problem on the solar radiation on the walls, and I noticed that initially, there are not any connection which give the solar radiation on the walls.

My conclusion is that to take account of the solar radiation on walls, we have to link it by ourself at the beginning, is it right or did I miss something?.

Furthermore, in the "wall type manager", there's a tab called "Solar Absorptance of wall". When I change the value, nothing change regarding the temperature inside the box. So when is this value used exactly?

Thank you in advance.

King regards


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David BRADLEY
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Thermal Energy Systems Specialists, LLC
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