The potential for demand-responsive lighting in non-daylit offices

Participants (N = 30) in an office laboratory had personal dimming control over lighting, and were then exposed to a simulated demand response (or "load shed") involving dimming lighting by 2 percent per minute. Participants were given no expectation that the dimming would occur, and the principal measure used was the point at which participants intervened to restore light levels after the demand-response dimming began. Results showed that 20 percent of participants intervened by the time that desktop illuminance declined similar to 35 percent from their initial preferred level, and 50 percent of participants intervened by the time that desktop illuminance declined similar to 50 percent. Therefore, during a power supply emergency, dimming lights can contribute relatively large electricity demand reductions before lighting declines to a level where a substantial fraction of people would be motivated to seek a change.