The Monsanto automobile Heat transfer Simulator (MHS) is a computer software package that is used to model the solar rejection performance of automotive glazing systems. The simulator allows user inputs that are descriptive of the vehicle design, the surrounding environment and vehicle operating conditions. A variety of glazing options is available, including absorbing and reflecting glass, laminated safety glass with absorbing or reflecting polyvinylbutyral interlayer, and hybrids of these materials. It is not necessary that all lights in the vehicle be of the same construction. Each light can be separately specified. The exposure environment is determined by specification of geographic location, time of year, time of day and vehicle heading. The specification of operating conditions includes the nature of the surrounding terrain, wind direction and speed, vehicle speed, vehicle ventilation and air conditioning.Outputs of the simulator include vehicle inside air temperature, internal surface temperatures for shaded and directly exposed parts of the vehicle, and the temperature of each glazing component. The simulator has two operating modes, a steady state “snapshot” mode and a continuous dynamic mode that operates over a 24 hour period.Operation of the simulator under static soak conditions has thus far shown excellent agreement with previous work conducted by Sullivan and Selkowits, Lawrence Berkeley Laboratory. In addition to predicting vehicle interior air and surface temperatures, the simulator also calculates a heat stress index as a measure of occupant comfort. The application of MHS to a broader variety of situations comprises essentially a logical extension of the Lawrence Berkeley work.