[TRNSYS-users] Sky temperature: which one to use?

[Francois Badinier]

Dear TRNSYS community,

 

It seems that there are some differences between the “ Effective sky
temperature” available in the weather component (e.g. Type 15-6) and the
“fictive sky temperature” calculated with the Type69b. The differences are
quite important and I would like to know which one I should “trust” to
calculate some IR-emissions towards the sky.

 

I  attached a simple testing project in which I plotted the following
graphs:

 

1.       The “effective sky temperature” , straight from the weather
component 

2.       The  ambient (dry-bulb) temperature

3.       The average between “effective sky temperature” and “ambient
temperature”

4.       The “fictive sky temperature” calculated by the Type69b (using
“total diffuse radiation” as an input)

 

What comes out of this graph is that the “average temperature” is quite
close to the “fictive sky temperature” calculated by Type69b. 

So where do the differences come from and which temperature should I use?

 

Thank you for your help.

 

François Badinier

Development Engineer

ICAX Ltd

1 Hatfield House 

Baltic Street West

London EC1Y OST

 <mailto:alan.kiff at icax.co.uk> francois.badinier at icax.co.uk

 <http://www.icax.co.uk> www.icax.co.uk

 

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