What are some standards or rules-of-thumb that can be used for daylighting design?

asked 2014-09-26 11:15:50 -0500

Matt Larson

1627 ●2 ●8 ●24 http://bigladdersoftware.com/

updated 2021-04-17 13:49:13 -0500

__AmirRoth__

4436 ●5 ●17 http://bleedinggreenna...

When doing a preliminary design for daylighting, what are some common standards or rules-of-thumb that people use to determine feasibility or to incorporate daylighting areas into an energy model? I've seen sources that state the daylighting depth would be 1.5 times the ceiling height, but I've also seen the daylighting depth would be 2.5 times the window-head height (floor to top of window) for example.

As a bonus question, I'm working on a basketball court in a gym with 34' ceilings where side daylighting is of interest. Would the same standard or rules-of-thumb apply when dealing with such high ceilings, or does it depend more on the window size/location at that point?

answered 2014-09-26 15:16:54 -0500

CJ
116 ●4

updated 2014-09-27 06:40:09 -0500

Julien Marrec

29032 ●85 ●74 http://www.effibem.com/

About the 34' high gym ceiling...I think you might want to avoid using thumb rules on that one, instead a short conversation with the lighting designer if possible. Do the windows start at floor level, or at least at low sill height? Or are they clerestory windows, with sill height of 15'? If the windows are placed high up, then the area near the wall will get less natural light most of the year, and the daylighting zone will get pushed inwards, like an island. Those type of questions will help distill the daylighting zone modeling criteria for you.

Also, about the ceiling height based daylighting zone depth...that thumb rule considers the possibility of considerable light first being reflected on to the ceiling, which then can be re-reflected into deeper space. Thus, check whether you have light shelves, or other daylight redirection devices in place, or the exterior ground being very reflective (then you gotta think about direct glare as well btw) etc.

For a good primer on daylighting thumb rules, see this 2009 Harvard presentation 'Daylighting, Rules of thumb'.

Hope this helps.

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Thanks @CJ, the Harvard presentation is a great tool for basic daylighting design and includes example applications to help you through the process and calculations. Definitely going to add this to my toolbox!