Achieving the LEED Light Pollution Reduction Credit

LEED SSc8: The Dark Sky
Point
James R. Benya, PE, FIES, FIALD, LC
BENYA LIGHTING DESIGN

LEED
US Green Buildings Council
Leadership in Energy and Environmental
Design
Over 14,000 projects to date. A rating system
• Qualified
• Silver
• Gold
• Platinum

Background
LEED 1.0 1998 Pilot
LEED 2.0 2000 Important
LEED 2.1 2002 Very Important
LEED 2.2 2005 Super important
LEED 3.0 2009 State of the Art

The Dark Sky Point
Intent
Eliminate light trespass from the building and
site, improve night sky access and reduce
development impact on nocturnal
environments.

The Dark Sky Point
LEED 2.1
Meet or provide lower light levels and uniformity ratios than those
recommended by the Illuminating Engineering Society of North
America (IESNA) Recommended Practice Manual: Lighting for
Exterior Environments (RP-33-99). Design exterior lighting such that
all exterior luminaires with more than 1000 initial lamp lumens are
shielded and all luminaires with more than 3500 initial lamp lumens
meet the Full Cutoff IESNA Classification. The maximum candela
value of all interior lighting shall fall within the building (not out
through windows) and the maximum candela value of all exterior
lighting shall fall within the property. Any luminaire within a distance
of 2.5 times its mounting height from the property boundary shall have
shielding such that no light from that luminaire crosses the property
boundary.

The Dark Sky Point
LEED 2.2 Original
FOR INTERIOR LIGHTING
The angle of maximum candela from each interior luminaire as located in
the building shall intersect opaque building interior surfaces and not
exit out through the windows.
FOR EXTERIOR LIGHTING
AND
Only light areas as required for safety and comfort. Do not exceed 80% of
the lighting power densities for exterior areas and 50% for building
facades and landscape features as defined in ASHRAE/IESNA
Standard 90.1-2004, Exterior Lighting Section, without amendments.
Note this is 4 zone based (LZ1-LZ4).

The Dark Sky Point
LEED 2.2 Original
LZ3 — Medium (Commercial/Industrial, High-Density Residential)
Design exterior lighting so that all site and building mounted luminaires
produce a maximum initial illuminance value no greater than 0.20
horizontal and vertical footcandles at the site boundary and no greater
than 0.01 horizontal footcandles 15 feet beyond the site. Document
that no more than 5% of the total initial designed fixture lumens are
emitted at an angle of 90 degrees or higher from nadir (straight down).
For site boundaries that abut public rights-of-way, light trespass
requirements may be met relative to the curb line instead of the site
boundary.

The Dark Sky Point
LEED 2009
For Interior Lighting
OPTION 1
Reduce the input power (by automatic device of ) all nonemergency interior
luminaires with a direct line of sight to any openings in the envelope
(translucent or transparent) by at least 50% between 11 p.m. and 5 a.m. Afterhours
override may be provided by a manual or occupant-sensing device
provided the override lasts no more than 30 minutes.
OPTION 2
OR
All openings in the envelope (translucent or transparent) with a direct line of sight
to any nonemergency luminaires must have shielding (controlled/closed by
automatic device for a resultant transmittance of less than 10% between 11
p.m. and 5 a.m.)

The Dark Sky Point
LEED 2009
For Exterior Lighting
Light areas only as required for safety and comfort. Lighting
power densities must not exceed NSI/ASHRAE/IESNA
Standard 90.1-2007 (with errata but without addenda) for
the classified zone. Meet exterior lighting control
requirements from NSI/ASHRAE/IESNA Standard 90.1-
2007 (with errata but without addenda) Exterior Lighting
Section, without amendments.

The Dark Sky Point
LEED 2009
LZ3: Medium (all other areas not included in LZ1, LZ2
or LZ4, such as commercial/ industrial, and highdensity
residential)
Design exterior lighting so that all site and building-mounted
luminaires produce a maximum initial illuminance value
no greater than 0.20 horizontal and vertical footcandles at
the site boundary and no greater than 0.01 horizontal
footcandles 15 feet beyond the site. Document that no
more than 5% of the total initial designed fixture lumens
(sum total of all fixtures on site) are emitted at an angle of
90 degrees or higher from nadir (straight down).

Tools
• Point by Point Lighting Program
• Photometrics of Proposed Lighting
• Site Plan

Planning
• What is the Path of Egress?
• Where is the site boundary?
• Is this a campus?
• What mitigating circumstances are there?
• Review Credit Interpretation Requests
(CIR’s).

X
X
X
X
X
X
X
Site Plan with Red “LEED” Boundary

Floor Plan Indicating Egress Points

Point by Point Analysis
Red is 0.01 fc line (LEED limit)
Purple is 0.1 fc line (minimum egress)

Red line = 10’ beyond curb
Magenta and green zones do
not directly comply
Identify non-complying zones

Make Your Case
• Is the difference
minor?
• Was it for a
good/necessary
reason?

Results

Analysis Tools

Future of LEED SSc8
• Change to match MLO,
ASHRAE/IES/USGBC 189, and other
evolving documents (BUG system, etc.)
• Retire the indoor lighting section
• Do away with light levels beyond the site
line and other measures used now

www.benyalighting.com
QUESTIONS?