Daylight Estimator for Sun Tunnel Skylights

The Daylight Estimator is a Sun Tunnel calculator tool that will give you the amount of light you'll get in a room based on your input.


1. Select the product (ies file) that represents the desired daylighting device (Luminaire)
Daylighting products are listed by product type, size, length of tunnel, and sun angle.

2. Define geometry of the space

Select the length, width, and ceiling height of the space. The work plane height should be 2.5' for most applications and the suspension length refers to the length that the diffuser penetrates the ceiling height, for most applications this should be set to 0. In open ceiling applications, the ceiling height is equal to the height of the roof and the suspension length will be set to something other than 0, if unknown, 2.5' is a good default value to use.

3. Define room reflectance

If the reflectance values of the space is known, insert them here, otherwise, use the following default values:

  • Ceiling: 80%
  • Walls: 50%
  • Floor: 20%
4. Specify number of Daylighting devices or desired illuminance (foot candles)

Either specify the illuminance which quickly is translated to a foot candle value or enter the number of daylighting products. If you enter an illuminance value, the program will automatically display the equivalent foot candle equivalent and tell you how many daylighting devices will be needed to achieve these results. If you specify a number of daylighting devices, the program will tell you how many foot candles this number of daylight devices will produce on average in the defined space.