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.

3.4 Skycalc® Example

The following results are for a typical small classroom 20' x 25' with 10' ceiling where SkyCalc was used to maximize energy savings.

Original Daylight Concept

Refer to the top sidebar image.

  • Single Center Skylight, 8' x 8' clear.
  • Total of 64 SF (12.8% SFR) with VLT =50%
  • Average light level: 604 fc (equinox clear)
  • Peak light level: 3928 fc
  • Typical light level: 80-100 fc
  • Minimum light level: 63 fc

Figure 16 - Source: Benya Lighting Design

Recommended Daylighting Revision

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  • 4 diffuse skylights, 2' x 2'
  • Total of 16 SF (3.2% SFR) with VLT=50%
  • Average light level: 121 fc (equinox clear)
  • Peak light level: 172 fc
  • Typical light level: 80-100 fc
  • Minimum light level: 72 fc

The bottom sidebar image shows how the original design would result in a net energy cost of over $1,500 while the new design would not only end up in better lighting but would result in a net energy savings of over $2,000 annually.

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