On our project we are planning to use luminaires, with greater than 3500 lumen rated outputs, which will be mounted to trees and aimed at a pedestrian bridge below. The luminaires we intend to use are spotlights equipped with extended shields. A product representative told us that these luminaires would meet IESNA Full Cutoff Classification except that they are mounted on swivel brackets. Provided that we aim these luminaires at an appropriate downward angle (let\'s say 33 degs above horizontal as a worst case scenario)would we have a problem meeting the LEED light pollution credit? Additionally, we are planning to use a second type of luminaire with an 1800 lumen rated lamp. For this luminaire, a very small percentage of the candlepower distribution curve is above the 90 deg line; however, at the property line, its illuminance level should be less than 0.05 footcandles. Would this be considered "appropriately shielded" for an E2: Low Ambient Brightness environmental zone?
If the following conditions are met then the credit can be attained. It may be possible to demonstrate that a swivel bracket luminaire will provide a Full-Cutoff lighting distribution and therefore comply with the Full-Cutoff requirement. Provide a photometric report of the proposed luminaire showing that at the intended aiming angle no light is emitted at or above 90 degrees, as delineated on page 19 of IESNA RP-33-99. Alternately, provide a drawing of the luminaire at the proposed aiming angle, showing that no part of the lamp or lens can be seen at or above 90 degrees from straight down. The credit requirements state that any fixture with more than 1000 lumens and less than 3500 lumens should be shielded. As defined in the Reference Guides, the purpose of shielding is to "limit glare, light trespass and light pollution". Assuming that the property-line illuminance of 0.05 FC has been calculated as a "line of sight illuminance" (see LEED-NC 2.1 Reference Guide, page 75) this value is below the 0.1 fc requirement. Applicable internationally.