Rating System

LEED BD+C: New Construction

Rating System Version

v2 - LEED 2.0

Inquiry

For the Light Pollution Reduction credit we have several questions: Question 1) LEED 2.0 states "zero-direct beam illumination leaves the building site". A formula had been submitted for the proposed revision of this Credit to determine an acceptable light level at the property boundary according to IES which is different that "zero": The formula is as follows: Ilos = (Ihor/Hlum-Hlos) X square root of (Dlum2 +(Hlum - Hlos)2), where: Ilos = The line-of-sight illuminance Hlum = the height of the identified luminaire lens above the ground Dlum = The distance from the point on the ground directly below the center of the lens of the identified luminaire to the property line Hlos = The height above ground of the typical line-of-sight at the property line Ihor = The initial horizontal illuminance at the property line due to the identified luminaire, calculated at a height of Hlos. We propose to demonstrate that we meet IES RP-33 maximum illuminance levels at the property line rather than ensuring "zero direct-beam illumination". Question 2) Do IES RP-33 Recommended Maximum Illuminance Levels call for an absolute maximum or a maximum average? This is not clear in either the standard itself or the LEED Reference Guide. Question 3) Do IES RP-33 Recommended Maximum Illuminance Levels refer to the maximum light tresspass level from any point on the site as well as off the site or only from off the site? Note that IES RP-33 refers to these values as "suggested light tresspass limitations", whereas the LEED Refernce Guide Table 1 calls these "Maximum Brightness Levels" without using the word tresspass.