Electric lighting consumes for 30% to 50% of electrical energy used in large commercialsbuildings, and has significant impact on cooling energy requirements. Thesintegration of daylighting with electric lighting to provide ambient illumination and providingstask lighting separately at each workstation is an attractive strategy for energysconservation. Energy savings come from proper control of the electric lighting system insresponse to available daylight. Building-level energy use measurements are generallysinsufficient to determine how well a building is operating. Detailed measurements ofsenergy used by separate building components are needed to understand how a particularsbuilding system is operating.

This paper describes instrumentation used to monitor the electrical energy consumption and illumination levels in a recently completed 56,000-m2 office structure in the SansFrancisco Bay Area. Interfacing of the temperature, electrical, and illumination measurementssto the dataloggers is described. Data acquisition in this occupied building presentssseveral challenges. Researchers needed to make measurements quickly, with minimal disturbancesto occupants by equipment and wiring, in four quite different daylighting zonessseparated by large distances--all on a limited budget. We give a brief description of thesbuilding and the issues to be addressed by this monitoring project. We then describe thesinstrumentation installed in the building to measure both lighting levels and electricspower consumption. Finally, we present and discuss typical results that can be obtainedswith this instrumentation.