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Hi everyone,
In my project, I wanted to use the External radiation calculation option for external surfaces in Type 56 – multizone building.
I found an example using it in the step 5 of the 3D building tutorial : C:\TRNSYS18\Examples\3D_Building\5_Step_Modify3D_Trnsys3d\Building_step5.tpf
In this example, the radiation data from Type 15 are supplied in kJ/h/m2 to Radiation Unit converter. They are converted in W/m2. Then supplied to Type 56 where they are expected in kJ/h/m2.
Do I have to supply the radiation data in kJ/h/m2 or W/m2 ?
Thank you !
Arnaud Beaulac
Arnaud,
You're correct about the function of those equations: they convert the data in the weather file from kJ/h.m2 to W/m2. However, those equations (at least in the example as distributed) aren't connected to the building. They are instead connected to a solar radiation plotter just to display the solar radiation in more standard units. If you set Type56 to take its solar radiation values as "external calculation" (rather than obtaining them automatically and internally) then those values must be provided to Type56 in kJ/h.m2.
Generally speaking in Trnsys, you should not change the units of inputs using the pulldown in the proforma. If you do, then bear in mind that no automatic unit conversions are performed. Inside the code, the Type gets an input value that is equal to the output value of the Type that is producing the output; no conversion is performed regardless of what the proforma indicates the output and input units to be. It is okay to change the units of parameters in proformas. I am always hesitant to mention it but you can also change the units of UNCONNECTED inputs. However, it is not recommended to do so because of the potential for later connecting that input up from the output of another Type and mistakenly thinking that a conversion will be performed.
kind regards,
David
