Automatically reduce artificial light energy load when natural daylight is available.
Provide automatic lighting controls for 80% of fixtures that fall within the Daylit Zones of the building. Install photocell sensors in combination with artificial lighting that provide multi-level or dimmable lighting based on the amount of natural light available to achieve appropriate light levels.
The building shown is 40 ft. by 60 ft. and features glazing on the front and left side with a skylight in the right rear corner. The daylit area is 1,300 sq.ft. (non daylit area is 1,100 sq.ft.).
Determine percent daylit zone = 1,300 sq.ft. / 2,400 sq.ft. = 54%
Daylit Zones - areas naturally lit by top or side glazing. For vertical glazing, the daylit floor area is calculated by adding two feet to either side of the wall containing the window and projecting 15 feet into the space. For top glazing, the daylit floor area is the footprint of the skylight + 70% of the ceiling height added to each side of the footprint. Daylit floor area terminates at full-height vertical partitions.
- Construction Documents indicate Daylit Zones and include a Lighting Schedule, detailing types and locations of controls
- Inspection by ECLC Technical Advisor