1.1 ,This guide provides quantitative and qualitative tools for evaluation of indoor air quality (IAQ) models. These tools include methods for assessing overall model performance as well as identifying specific areas of deficiency. Guidance is also provided in choosing data sets for model evaluation and in applying and interpreting the evaluation tools. The focus of the guide is on end results (that is, the accuracy of indoor concentrations predicted by a model), rather than operational details such as the ease of model implementation or the time required for model calculations to be performed.