Page 115 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

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zones, the site property line can be moved out to the curb line on portions of the
lot that abut public rights-of-way. Also, for all zones, there is an allowance for a
single luminaire at the intersection of a private driveway and a public roadway in
LEED 2009, which can illuminate beyond the property boundary as previously
noted.
Submittals for this part of the exterior lighting requirement must include site plans
that show both the maximum horizontal and vertical illuminances at the site boundaries
as well as values of the maximum horizontal illuminances extending out the stated
distance(s) beyond the boundaries. The horizontal lighting intensity plans are typically
referred to as isoluxes or isofootcandle plans and give either contours or spot values of
luxes or footcandles. Vertical lighting distributions at all the property lines (or curb
lines or as extended at driveways) should also be provided. Isoluxes show the additive
effects of all the lighting fixtures in the area, and they cannot be based solely on each
individual fixture.
The submittal for the fourth item in this part of the exterior lighting requirements
needs to consider all the exterior lighting fixtures on the site. It is based on the initial
designed fixture lighting capacity (lumens) for each, as most lighting fixtures have a
reduction in lighting intensity with age. Determination of whether the requirement has
been met, can be performed by following these three steps:
• The total initial designed lumens for all the exterior site fixtures should be
added. This will be referred to as the total initial designed lumens (TIDL).
• In addition, any of the fixtures that have any light aimed at an angle which
breaks above a horizontal plane with the fixture should have the associated
lumens that shine in this direction summed over the site. This will be referred
to as the total initial designed angled lumens (TIDAL).
• If the maximum allowed percent of total initial designed fixture lumens emitted
at an angle of 90 degrees or higher from nadir is referred to as the maximum
initial designed angled lumens (MIDAL), then this requirement can be met if
Eq. (2.8.1) is valid. The applicable values for MIDAL for each zone are given in
Table 2.8.3. The exception to Eq. (2.8.1) is in cases where no exterior lighting is
installed; then the requirement is automatically met.

100(TIDAL/TIDL) ≤ MIDAL (2.8.1)

A strategy for meeting this fourth item in part 2 of the exterior lighting requirements
may be to specify and install appropriate shielding and cutoffs on the exterior
fixtures.

Special Circumstances and Exemplary Performance
Figure 2.8.2 gives a summary of the interior and exterior requirements necessary for
fulfilling this credit in LEED 2009.
If there are special circumstances or considerations for this credit, a narrative must
be submitted describing these circumstances. There is no EP point available as related
to this credit.