Airflow patterns and thermal behavior of mechanically ventilated glass double façades

Glass double façades (GDFs) are finding increasing use in commercial buildings, but are difficult to design. Of key significance for the cooling load of the building and thermal comfort of its occupants during summertime are the total solar energy transmittance to the interior and the temperatures of the inner pane. A procedure for modeling such façades—comprising a spectral optical and a computational fluid dynamic model—is described and simulated results are compared with data derived from an experimental investigation of two mechanically ventilated GDFs built in an outdoor test facility. It is shown that simple models assuming piston-flows can lead to inaccurate results.