AT-84-16-1 -- Fenestration for Optimal Use of Daylight and Solar Radiation PDF

A method of calculation of outdoor available solar radiation and daylight on inclined surfaces for overcast, clear, and longtime average sky conditions is developed. The method is proved for different weather stations and gives results for the average sky within plus or minus 10% of measured values.

On this basis the daylight in interiors can be calculated, where for economic considerations the relative time of use, Trel, for average conditions is important only (Trel is that part of the annual working time during which the daylight level at the working place is sufficient).

For known characteristics of window materials, it is also possible to calculate:

• the solar radiation entering the interior, for clear sky conditions, which is important for maximum cooling load;
• the inside solar radiation for average sky conditions, which is important for energy consumption for cooling during the warm season and for heating during the cold season.
  

Results of calculations according to this method are now used in German standards.

By this method, it is possible to optimize the window area with respect to minimum energy consumption for electric lighting, and for heating and cooling of buildings.