Skylights

A skylight is a fenestration* surface having a slope of less than 60° from the horizontal plane. Other fenestration, even if mounted on the roof of a building, is considered vertical fenestration. 

*Fenestration is all areas (including the frames) in the building envelope that let in light, including windows, plastic panels, clerestories, skylights, doors that are more than one-half glass, and glass block walls.

Energy Asset Score Inputs for Skylights:

Name – Default component text and counters are automatically added. This entry may be edited to include other descriptive or identifying text.

Skylight Type – Refers to the glazing material of the skylight. Pull-down menu selections: Glass or Plastic

Skylight Properties – Optional inputs (if no values are given, values will be inferred):

U-VALUE – Thermal transmittance per unit time per unit area of the whole window and the boundary air films, induced by unit temperature difference between the environments on each side. U-value is the inverse of R-value. U-values are given in units of Btu/ft²•°F•h

SHGC – Solar heat gain coefficient (SHGC) is the ratio of the solar heat gain entering the space through the fenestration area to the incident solar radiation. SHGC is measured on a scale of 0 to 1; values typically range from 0.25 to 0.80

VT – Visible Transmittance (VT) measures the amount of light the window lets through. VT is measured on a scale of 0 to 1; values generally range from 0.20 to 0.80

Skylight layout – After assigning a skylight to a building block (see the Assign Use Types and Components section), available pull-down menu selections for Skylight layout include All Zones and Core Only

% of Roof Area – The skylight area as a percentage of the total roof area. Typical values range between 3% to 5% of roof area, though a maximum of 95% may be entered to accommodate buildings with atriums. If Core Only was selected as the Skylight layout, the equivalent area of skylights will be uniformly distributed over the defined zones.