| Popis: |
Linking occupancy sensors to switches or dimmers is a well-established strategy yielding substantial lighting energy savings. Indeed the technology is considered proven enough that it is now mandated for many space types in most commercial buildings via all major energy codes. Current codes typically require a maximum 30-minute timeout or delay following the last detected occupancy before switching lights off. New codes may reduce this timeout to 20 minutes, promising more savings. It has been long recognized that reducing timeouts further, to 5 minutes or less, will deliver even greater savings [1, 2]. So, why aren’t energy codes more aggressive in mandating shorter timeouts? There are two principal answers to this: (1) prevailing sensor technology is not reliable enough to detect occupancy at such short timescales; (2) even if the sensors were reliable, shorter timeouts would mean more frequent switching, potentially reducing the lifetime of fluorescent lamps to an uneconomical degree. In this article we re-evaluate the potential energy savings of shorter timeout periods with two datasets, and discuss how such timeouts might be viable with LED technology. |
