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Daylighting

Reducing the amount of powered lighting that is used when sufficient natural daylight illuminates the interior building through windows and skylights is called daylighting. Automatics daylighting control systems are a very common energy efficiency measure in buildings and are often required for new building designs depending on the energy code that applies to the building location. The most common input objects related to daylighting are:

  • Daylighting:Controls -- specifies the algorithm used for daylighting, the dimming of lights is continuous or stepped, and how glare calculations are performed.
  • Daylighting:ReferencePoint -- specifies the location of the sensors for the daylighting control system.

The InputOutputReference includes not only a description of these input objects but also extra guidance on how they should be applied. The PurchAirWithDaylighting.idf contains examples of these input objects.

Daylighting with Continuous Dimming

Daylighting with Continuous Dimming

Three different devices can be used with daylighting:

  • DaylightingDevice:Tubular - see the DaylightingDeviceTubular.idf example file.
  • DaylightingDevice:Shelf - see the DaylightingDeviceShelf.idf example file.
  • DaylightingDevice:LightWell - see the GeometryTest.idf example file.

An input object called Daylighting:DELight:ComplexFenestration is used with one of the two control methods specified in the Daylighting:Controls input object when used in conjunction with complex fenestration systems such as prismatic and holographic glass.

Some flexibility is given to provide extra output related to daylighting and includes:

  • Output:DaylightFactors -- creates a special report on the factors used in daylighting. See the ReportDaylightFactors.idf example file.
  • Output:IlluminanceMap -- allows the generation of maps of illuminance values within each interior zone that uses daylighting controls. The exact file format can be set using the OutputControl:IlluminanceMap:Style input object. See the DaylightingDeviceTubular.idf for example of both input objects.

More details of these output options can be found in the OutputDetailsAndExamples document. The input objects described in this section are further explained in the InputOutputReference under the heading "Group-Daylighting."