Since the mid-1970's, a cumulative $70 million investment by the Department of Energy in energy efficiency programs at Lawrence Berkeley Laboratory has helped to spawn a $ 2.5-billion annual U.S. market for four particular technologies and services: high efficiency windows, high-frequency fluorescent lamp ballasts; residential equipment efficiency standards; and computer tools for energy-efficient building design. As of 1993, this R&D investment has resulted in $6 billion in energy savings, an amount that will grow to $20 billion over their entire service life (with net return on investment for consumers of $10 billion). The advances in window technology drew upon a wide variety of Laboratory strengths as teams of research architects and thin film material scientists worked with physicists and engineers with an understanding of solar and indoor radiation, the reflective and adsorptive properties of materials, and the technology for manipulating these materials for enhanced performance.