Empirical Validation of Solar Gain Modeling

The purpose of this paper is to provide an overview about the level of detail and methodologies used in an empirical validation for assessing solar gain models in building energy simulation programs. In this study, a series of experiments is being performed in a test cell located on the Duebendorf campus of the Swiss Federal Laboratories Material Testing and Research (Empa) facility in conjunction with the International Energy Agency’s (IEA) Task 34/ Annex 43 Subtask C. The objectives of these experiments are to examine solar gains through a glazing unit with various internal and external shading devices. The results from the experiments are being compared to models of each experiment created in numerous building energy simulation programs. To make comparisons, a comprehensive set of statistical parameters is being employed to evaluate the performance of the programs. Particular emphasis was placed on estimating the impact of experimental uncertainties in the measurements used for comparisons between the program outputs and the experiments and inputs to the building energy simulation programs. Monte Carlo and N-way Factorial Analyses were used to evaluate how experimental uncertainties in the input parameters propagated through the building energy simulation programs and impacted outputs. Examples of comparisons for selected experiments are also described in this paper and a discussion of key factors that influenced the validation efforts.