[esp-r] Re: recent question on solar radiation

[Jon Hand (clcv10)]

Some recent questions about reporting solar radiation...

> m trying to compare ESPr with other software based on climate data.  
> Some queries on that behalf:
>
> 1-the output 'Solar absorbed in zone' involves all the irradiation  
> absorbed by the building ?
>
> Is there any way to discriminate  this data 'per surface'?

Yes, part of the surface energy balance is the shortwave radiation  
absorbed (combined
direct and diffuse) and you can get this in the surface energy  
balance report or select
this data type in the timestep listing option or graph it in the  
graphing function or get
statistics in the enquire about section of the results analysis module.
>
> 2-Can we assume that Solar Diffuse is the same as Diffuse  
> Horizontal (from the climate data )?

This is likely to be true (solar data are a part of dozens of  
different reports). If you really want
to be clear about the semantics look in the source code (see note  
below).  We know of many
users who have set up various virtual experiments which they have  
used to understand the
distribution of radiation.

>
> 3- Which value represents 'Solar Direct'? Is that the horizontal  
> component of Direct Normal?
>
This depends on what type of direct solar radiation is held in the  
climate module.

If you want to find out a lot more about how radiation is tracked  
within ESP-r you could
turn on the solar trace option in the simulator.  And in the source  
code look in esrubld/solar.F
for more about the theory and calculations performed.

-ESRU