SkyCalc Design Assistant

Sky-Calc is a skylight assistant program designed to determine luminance levels plus aid in determining potential energy savings with Daystar, a High Performance Natural Lighting System.

Download a copy of Sky-Calc from follow the instructions that are in the first page of Sky-Calc. This software utilizes weather files that are obtained by using eQuest. eQust can be downloaded from

The section with the “Input” tab has drop down menus. Select “Acrylic” for glazing type, “Double Glazed” for glazing layers, and “Clear Prismatic” for glazing color. Also, select “Reflective Foil” for well color.

The optional input tab contains several drop down menus that need to have the following values that reflect Daystar performance and characteristics. In the “User Revisions” column, insert the following, select “Dome” for skylight shape and use these values for the following inputs:

• Height of Dome: 0.75
• Visible Transmittance: 90%
• Solar Heat Gain Coefficient: 53%
• Frame Type: Metal with thermal break
• Unite U-Value: 0.33
• Dirt Light Loss Factor: 85%
• Screen or Safety Grate Factor: 100%
• Well Factor: 95%

Bottom of light well inputs are the size of units and diffuser on bottom of well select “Yes”.

This will aid when customizing Sky-Calc for Daystar. These inputs have been used with accurate results.