Long and short wave radiation

Hey guys,

For another simulation tool(Delphin) I’m using, i’m in need of the short-wave and long-wave radiation on a surface.

I thought that LB/HB could calculate it for me. I have done an annual radiation simulation on the surface. Does anyone know how to separate my output into long-wave and short-wave?


Hi Christian, Are you looking for values that are falling on the surface or the values that comes off the surface? In case of the latter, you can look to solutions with Radiance. The former though involves thermal properties of the materials and is something that you want to check using the results of EP. I have never done it myself so I don’t know the answer off the top of my head but you can check EnergyPlus Input/Output reference to find related outputs.

This is an interesting problem.

As long as you don’t consider reflections, (I think) you can calculate long-wave and short-wave using LB/HB with the Gencumulativesky module.It is probably easier to do with grid points than it is with an image based simulation. You can separate the radiation reaching a point into long-wave and short-wave based on the spectral power distribution of the solar spectrum. I am attaching an image below. This is also available in a Tabular format in Table 1.3.1a in Solar Engineering of Thermal Processes by Duffie (4th Ed).

The area under the curve represents the total radiation. You can derive long-wave and short-wave components by multiplying the total radiation with the weighting factors corresponding to each component.

(PS: Please cross-check with some scholarly articles before finalizing such an approach for any project/research)