Daylighting Collaborative


WEAC Building detail, Madison, Wisconsin

what/why > cool daylighting

Cool daylighting (or cooling load avoidance daylighting) is not a new term. It is a descriptive term to differentiate daylighting design that takes into consideration whole building energy impacts of integrated daylighting design from designs that do not do this.

It was most recently popularized by Steve Teorney of LIGHTFORMS working in cooperation with the Energy Center of Wisconsin and the Daylighting Collaborative to provide training on the daylighting approach that LIGHTFORMS used on its projects around the country.

Cool daylighting is truly a whole building approach to daylighting that looks to not only reduce electric lighting needs but to reduce (or at a minimum not increase) cooling loads within the daylit building. The cooling load is primarily a function of internal heat gain from lights, equipment, people and sunlight. Daylighting reduces the need for electric lighting and consequently the amount of heat produced by electric lights. When incorporating high performance glazing and exterior shading recommended for a comprehensive cool daylighting design, it also minimizes heat gain from the sun through the envelope. These overall reduced loads often result in a reduction in the size of the cooling system.

Another key issue associated with cool daylighting design approach forwarded by LIGHTFORMS is the use of balanced luminance ratios. Again, not a new concept, but a key part of the design parameters for achieving a cool daylighting design that uses low transmittance glass, exterior shading and strategic glass placement to achieve cool, glare free daylighting.