Basics of Daylighting in a Green Environment
The use of natural sunlight, known as daylighting, to illuminate a building can save energy, reduce operating costs, create visual appeal, and enhance occupant health and productivity. The U.S. Green Building Council Leadership in Energy and Environmental Design (LEED™) rating system encourages the use of daylighting to achieve high performance buildings. This course provides an introduction to the use of daylighting in commercial spaces. The course objective is to show why daylighting should be considered, the basic guidelines of using daylighting and some words of caution when using certain daylighting techniques.

5.2 By Task Location

The sidebar diagrams illustrate controlling rows of luminaires which are parallel to the source of daylighting.

  • The row nearest the window would be controlled by the photo sensor.
  • The row farthest from the window would be switched at the door.
  • The middle row would depend on how far it is from the window. If it is within 2 times the height of the window, it would probably be controlled by the photo sensor with the ability to override it at the door. Otherwise it would be switched with the row nearest the door.

Daylighting Controls Source: "Tips for Daylighting"

Daylighting Controls Source: "Tips for Daylighting"

Property of

"Tips for Daylighting" from Lawrence Berkeley National Laboratories offers the following suggestions regarding the placement of sensors:

  • Place sensor appropriate to the task location. In a room with only one task area, place the ceiling-mounted sensor above the task. In a room with more than one task area, place the ceiling-mounted sensor above the task that best represents the daylight available. Some controllers support inputs from more than one photo sensor. This allows daylight to be sampled at more than one location.
  • Sensor placement is determined by the daylight control algorithm. For closed-loop control systems, locate the sensor at a distance from the window equivalent to approximately two-thirds the depth of the daylight control zone. Photo sensor location is less critical with open loop systems, and can be compensated for during commissioning. With a light shelf and an open-loop control system, locate sensor above the shelf.
  • Sensor placement differs with the type of lighting system. With indirect and direct/indirect lighting systems, the photo sensor should be located in the plane of the fixtures aimed downwards. Make sure that the sensors cannot directly "view" the electric lights they control. For direct lighting systems, recess the photo sensor(s) in the ceiling.
  • Sensor field of view is important. The photo sensor's field of view should not be too narrow and restricted or the sensor will be too sensitive to small incidental changes such as papers moving on a desk or people nearby. A ceiling-mounted closed loop sensor should have a large field of view and be shielded from direct light from the window. Some sensors come with sun shields for cases where the cell cannot be placed far enough from the window. For switching systems, the photo sensor (often a photo relay) is located so that it "views" the external daylight source with minimal (or no) view of the electric lights that it controls.
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