Energy-efficient U.S. buildings and equipment: Progress toward least lifecycle cost

New energy-conserving technologies for the buildings sector are reviewed, and it is argued that such technologies have the potential to cut specific energy use (per house, per refrigerator, per square meter of commercial floor space) approximately in half within 20 yr, at economically justifiable cost. Technologies for efficient lighting and for efficient windows are described, with emphasis on those now being investigated at the Lawrence Berkeley Laboratory. Modern approaches to lighting are discussed, involving gas discharge lamps with dynamic controls, high-frequency solid-state ballasts, mercury vapor with altered isotope composition to reduce ultraviolet self absorption, and external magnetic fields parallel to the main current. Modern approaches to windows designed to improve overall annual thermal performance are also discussed; these include low-emittance surfaces in the infrared (heat mirrors), movable insulated window shades, and silica aerogel, an intrinsically insulating microporous glazing material with good optical properties.