Daylighting - Prescriptive Calc

Generally, yes, it is possible to have too much daylighting. However, without knowing more about your project and calculations I can't say for sure. Are you excluding all non-regularly occupied spaces? Is your VTL correct?Alternatively, assuming your calculations are correct here's what the credit language says: "designs that incorporate view-preserving automated shades for glare control may demonstrate complianc efor only the minimum 0.150 value" 

Your going to have to incorporate all of the floor sales area, looked at options for you in LEED for retail and could not find any. One strategy is to break up the space into zones. So determine your bay depth based on window height, and then seperate the space. If the space has bilaterally daylit, such as form three sides, seperate your zones that way. The language does say the length of the zone is wall to wall. So to argue this you need have a either a change in glass properties or size. For example, along your one wall that is 40 ft long, you have have the length with glass that runs from sill height to 10ft, then then other half is floor to ceiling. It would be justifiable to argue that these are two separate zones based on the change in glass. Will it get you in between .15 and .18, i don;t know. I ask you this, was the daylight credit a before or after thought with this project? If you want to incorporate daylight, then it needs to be in the DNA of the design. If you are attempting this credit as an after thought, then the prescriptive path is doing what it is kind of meant to do, that is set a standard for projects that have not incorporated daylight into the design to ensure spaces are not over lit and that the amount of glazing is reasonable as far as handling solar heat gain and loss. If the project is a glass box then i would suggest the other options.

Francisco,Just click the "credit language" tab above. You can also find it in the addenda to the reference guide. I believe it was in the May 2011 addenda.