Impact Assessment and Performance Targets for Lighting and Envelope Systems

Electrical source energy use in California accounts for over 55% of all primary energy use in the building sector (CEC, 1990). In the commercial building sector, 38% of electric energy consumption is directly attributable to lighting and 19% for cooling. These two major interrelated building subsystems, electric lighting and cooling from the building envelope, also account for more than half of typical peak demand in California buildings. The exterior envelope of the building, primarily the glazing, is a major source of peak cooling demand and of annual cooling load; it is also a potential source of daylight that may be exploited to offset electric lighting loads. Despite improvements in lighting technology, especially new lamps and ballasts, lighting remains a key contributor to energy use, load shape, and peak demand. Lighting controls, integrated with daylighting, afford the opportunity to significantly reduce lighting requirements and cooling loads.

We present in this document an assessment of achievable energy and peak demand performance in California commercial buildings with an emphasis on building envelope and lighting technologies available today and in the future. After first characterizing energy performance over a large range of building envelope and lighting conditions, both through computer simulation models and through case study measured data, we subsequently determine reasonable energy targets if building design were further optimized with integrated systems of current or new technologies.