A mathematical model describing the spatial and time distribution of energy produced by lighting has been constructed. The model is based on well-known heat-exchange computation procedures and contains no empirical coefficients from lighting energy-transfer experiments. A computer program based on this model was used to generate predictions of cooling loads created by lighting for a variety of building-lighting arrangements, airflow paths and rates, and lighting duration. Comparisons of model predictions are made with published experimental steady-state and transient results. The modeling procedures and the transient comparisons are described in detail.