OFFICE LIGHTING-should feature energy conservationand good color. A good choice is the T8 3500K to 4100Ktriphosphor linear lamp or a similar compact fluorescentunit with high-frequency electronic ballast. High-intensitydischarge lamps can be used for indirect lighting inspaces with high ceilings. Color-corrected high-pressuresodium (HPS) and metal-halide lamps with high CRI ratingscan be used as well. Incandescent lamps may be usedin storage areas, closets, and other spaces with short burningtimes. Incandescent and tungsten-halogen lamps areappropriate for illuminating displays. Power limits for office spaces at 1.5 W per square ft for PRIVATE OFFICES

And 1.3 W per square ft for OPEN PLAN OFFICES

The limit for OFFICE CORRIDOR is 0.7 W per square ft,

And 1.8 W per square ft for RECEPTION and LOBBY AREAS.

CONFERENCE and MEETING ROOM are allowed 1.5 W per square ft.

ACTIVE STAIRS are set at 0.9 W per square ft,

And ACTIVE STORAGE is allotted 1.1 W per square ft.

The room surface reflectance levels for offices are criticalto support the lighting design. The IESNA recommendations for office-type spaces suggest that ceilingsshould have 80 to 92 percent reflectance, with perforatedceilings being about 15 percent lower than their finish.Walls and partitions should average in the 40 to 60 percentrange. The floor should be between 20 and 40percent reflectance, and window blinds should be in the 40 to 60 percent range. Desktops, furniture, and office machines should have reflectances of 25 to 40 percent.Indirect lighting with a ceiling at least 3 meters(10 ft) high is recommended for lighting spaces withcomputer monitors. Semi-indirect and direct-indirectlighting may be used in spaces with ceiling heights between2.75 and 3.36 meters (911 ft). With indirect

Many industrial buildings are one story, and roofmonitors, skylights, and clerestories can provide daylighting.These light sources must be accessible for cleaning.Artificial lighting sources should be highly efficient,retain their brightness over time, and offer long life. Fluorescentand HID lighting are the best choices. New inductionand sulfur lamps may be good alternatives, withadditional development and field-testing. HID is easierto maintain, store, clean, and relamp than fluorescentlighting. However, HID has a delay in restarting.Minimal reflectances for industrial ceilings are between75 and 85 percent. Walls range from 40 to 60percent reflectances, with equipment at 25 to 45 percentand floors at around 20 percent.2