I am currently estimating the solar gains according with ISO 13790:2008. To accomplish that, incident solar radiation is needed. Ecotect Help provides information in how Solar Radiation is calculated in a given surface. However, the formulae presented is confusing, due to the parameter Fshad (formulae: Eincident = [(Ebeam x cos(A) x Fshad) + (Ediffuse x Fsky)] x ExposedArea). Since it is intended to calculate the solar incident radiition, why do Ecotect algorithm considers the beam solar radiation multiplied by the fraction of the surface currently in shadow from other surrounding geometry, as Fshad is defined in Ecotect Help menu. My question derives from comparisons of solar radiation calculations with Ecotect and other (reliable) method, when using the same climate data source, showing that Ecotect values are underestimated.
Can someone explain me the possible cause for these deviations?
I've founded the same problems...the incident energy of a surface exsposed to sud with 30° is 1200 kwh/m2 for years...the real energy is 1600-1700 kwh/m2 for year..