Use measured incident radiation on the surface

[FLECAR]

Hello,

I will study a façade where I can install experimentally a pyranometer on the façade surface (incident radiation on the surface). Would it be a better, worst or equivalent solution than measure the horizontal global and diffuse radiation if I want to compare my results with the equivalent WUFI model ?

Thanks

[Thomas]

Hi FLECAR,

if you install a pyranometer on the surface under investigation, you will need only one pyranometer instead of two for global and diffuse radiation (unless you wish to investigate more than one facade). Converting from global and diffuse measurements to an inclined surface always involves some model assumptions and is never as accurate as a direct measurement. The pyranometer on the facade will also measure local peculiarities which could not easily be taken into account in a conversion calculation, such as occasional shading of the facade by local objects (trees, houses), or the radiation reflected by the ground, with possibly variable reflectivity.

On the other hand, these measurements can only be used for this purpose and for this specific facade. Measuring global and diffuse radiation on a horizontal surface allows you to convert the data for any number of surfaces with any orientations and inclinations.

Regards,
Thomas

[FLECAR]

Thank you very much Thomas!