Thermal comfort of passengers is essential when they enter a vehicle parked in the sun for an extended period. Quickly achieving this comfort level and reducing fuel consumption at the same time can be accomplished by using electrochromic (EC) glass. Keeping the interior of the car cooler by controlling EC windows increases the fuel economy, comforts passengers faster and protects the vehicle components exposed to heat and solar radiation. The optical properties of EC glass are compared with other types of currently available glass types. The power load comparisons are analyzed through a software package, VSOLE. In VSOLE models, transmitted, absorbed, and reflected solar radiation analyses are conducted as functions of the optical properties of glass glazing, providing valuable insights on the usability of EC glass. (C) 2002 Elsevier Science B.V. All rights reserved.