Equivalent shape factor of buildings in solar-enriched areas

Analyses the problems existing in the building envelope thermal performance design in solar-enriched areas with heating only. Proposes the concept of equivalent shape factor, and gives its physical meaning and calculation method. The research results show that the solar heat gain of a transparent envelope is greater than the heat loss during a certain orientation scope, which makes it become a heat gain surface. The equivalent shape factor should be expressed as the external surface area of building directly in contact with outdoor air minus the equivalent area corresponding to effective heat gain surface divided by the volume enclosed. Compared with the shape factor, the equivalent shape factor has a high degree correlation with the heat loss per unit volume, and the R square can reach above 0.90. Using the equivalent shape factor substituted for the shape factor as the basis for envelope thermal performance design of passive solar building can lead the designer to optimize building orientation and adopt larger window to wall ratio.