IES-VE User Forum

Hi everyone,

I've been looking at the solar gains for a model. I've been using SunCast and ApacheSim to collect some data for various building surfaces and I'm seeing some interesting results.

Here are the results from one building surface for one hour in one day:

On ApacheSim (VistaPro): Ext Surface Incident Solar Flux = 232 W/m2 (@12.30 midday)

Now to crosscheck these results...

On SunCast, on the same surface from 12:00 to 13:00 on the same day:
0.5kWh/m2 = 500 Wh/m2 = 500/3600 W/m2 = 0.138 W/m2

These should be roughly the same, however they're completely different. SunCast is producing very low results.

Am I missing something really obvious here? (Usually the case with something that should be trivial)

Hi Harry,

Dividing the 500 Wh/m² by 3600 will give you the results per second which isn't what you want.
The 232 W/m² in VistaPro is a single value, however the 0.5 kWh/m² in SunCast is the accumulation of two values at 12:00 and 13:00.

If you add up the Ext surface incident solar flux values at 12:30 and 13:30 then divide by 1000 you should roughly get what you see in SunCast.
I say roughly due to the number of decimal places displayed.

Please see section 5.1 of the SunCast User Guide for more details.

John