Title: Analytical and Empirical Evaluation of the Impact of Solar Control Glazing on the Thermal Environment in Vans
text: Spectrally selective glazings that reduce the amount of solar energy entering a vehicle have been developed by PPG to enhance overall passenger comfort and help automotive designers and engineers manage the thermal environment in vehicles. That environment is being affected by such factors as the use of larger glass surfaces, smaller engines, fuel economy goals and refrigerant issues. To quantify the effects of a variety of solar control glazings on passenger comfort and thermal environments, PPG has conducted in-vehicle tests in Arizona evaluating the following glazing systems: the SUNGATE® Automotive windshield, which uses a transparent infrared-reflective coating; SOLARGREEN® Glass, a special composition that reduces infrared energy transmittance, and GL-20™ Glass, a deep-tint privacy glass. The evaluations included measurements of passenger compartment air temperatures, material temperatures, air flow, heat flux through non-glass surfaces, passenger comfort and air conditioner performance. Test results show that these glazing systems are effective in reducing maximum temperatures in parked vehicles, improve cooldown performance following static exposure and reduce compressor work loads. This all leads to improved passenger comfort, improved fuel economy and less damage to interior materials. While desert testing will continue to play a role in assessing in-vehicle performance of glazing systems, there is a need to provide such information in real time as auto manufacturers continue to reduce their development cycle. To that end, a predictive analytical model has been developed. The foundation for that approach is a thermal simulation code that has been modified to allow changes in orientation and the capability to use short time step boundary conditions. Initial efforts in this project, both analytically and empirically, have been focused on simulation of the minivan vehicles. The dynamic nature of both the simulation and the empirical drive test required observation of additional temperature, flow and heat flux sensors throughout the vehicle. Comparisons of the simulation models to empirical results confirm that the analytical approach captures the measured performance of new glazing products in vehicles.