A semi-empirical method for estimating the performance of direct gain passive solar heated buildings

The sunspot code for performance analysis of direct gain passive solar heated buildings is used to calculate the annual solar fraction for two representative designs in ten American cities. The two representative designs involve a single thermal storage mass configuration which is evaluated with and without night insulation. In both cases the solar aperture is double glazed. The results of the detailed thermal network calculations are then correlated using the monthly solar load ratio method which has already been successfully applied to the analysis of both active solar heated buildings and passive thermal storage wall systems. The method is based on a correlation between the monthly solar heating fraction and the monthly solar load ratio. The monthly solar load ratio is defined as the ratio of the monthly solar energy transmitted through the glazing aperture to the building's monthly thermal load. The procedure using the monthly method for any location is discussed in detail. In addition, a table of annual performance results for 84 cities is presented, enabling the designer to bypass the monthly method for these locations.