Effects of Glazing and Ventilation Options on Automobile Air Conditioner Size and Performance

The Lawrence Berkeley Laboratory has performed a preliminary analysis of the effects of glazing and ventilation on automobile cooling loads and air conditioner capacity limits. The study was accomplished as part of the Environmental Protection Agency's efforts to reduce the release of chlorofluorocarbons into the earths atmosphere from automobile air conditioners. We investigated the characteristics of standard and sports-model sedans using numerical simulations of the heat transfer processes under static-soak conditions. In addition, an annotated bibliography was created that documents other relevant research relevant to both static-soak and highway driving conditions.

These studies and our own results suggest that:

• Glazing is a major contributor to the cooling loads that dictate the size of automobile air conditioners.
• The use of new glazing technology in conjunction with other design features, e.g., ventilative cooling when parked, provides a viable means of reducing cooling system size in many parts of the country.
• Continuing work is needed to perform additional analytical and experimental investigations under highway driving conditions that will document the magnitude of the cooling unit size reduction possibilities.