COMMERCIAL BUILDINGS THAT BENCHMARKED THEIR ENERGY USAGE WITH
THE EPA’S PORTFOLIO MANAGER TOOL REDUCED THEIR ENERGY BILLS
ON AVERAGE BY 7% OVER THREE YEARS.
10 BUILDINGS 10.15
The Next Frontier in LED Efficiency
LEDS WITH INTEGRATED CONTROLS for daylight and occupancy had a 69% decrease in wattage
compared to a baseline average of GSA buildings with fluorescent lighting. The decrease was higher
(75%) compared to the national average. Source: GSA.
$4.00 $3.75 $3.50 $3.25 $3.00 $2.75 $2.50 $2.25 $2.00
Installed Cost ($/ft2)
GSA Avg. Lighting Baseline (EUI: 3. 25 k Wh/ft 2 /yr) : 69% energy savings
U.S. Avg. Lighting Baseline (EUI: 4.1 k Wh/ft/yr) : 75% energy savings
d eta m its E
ROI on LEDs with Onboard Controls
Current cost with GSA average lighting use and $.10/kWh
1.4 SIR—savings exceeds investment by 40%
The energy and maintenance sav-
ings from relamping with LEDs
are well known. But incorporat-
ing daylight and occupancy sensors into
the fixtures themselves raises efficiency
to a new level, according to a study by the
Lawrence Berkeley National Laboratory
(LBNL) for GSA’s Green Proving Ground
The LED fixtures were installed at
Chicago’s Metcalfe Federal Building
and Atlanta’s Peachtree Summit Federal
Building. The LEDs integrate advanced
lighting control systems (ALC) that
can switch, dim and brighten lights in
response to daylight and occupancy. The
study notes that the initial cost and complexity of implementing such controls has
often been prohibitive when the controls
have been standalone rather than built
into the LED fixture.
Replacing Recessed Fluorescent
The applications in the two GSA buildings minimized installation costs by using
the wiring of the legacy recessed fluorescent fixtures. Earlier implementations of
onboard ALC have required complex programming to assign fixtures to lighting
zones and make connections to strategically placed sensors. The ALC-integrated
LEDs were programmed and assigned to
zones using handheld remote controls. After the supplier programmed a few sample
zones, facility staff and contractors were
able to program the rest.
“The system was so easy to set up that it
literally took us less than an hour to commission all 300 fixtures – and we didn’t
need an engineer or program specialist to
do it,” says Joshua Westhouse, Building
Manager of the Metcalfe building.
Once zones are set up, the fixtures
within them communicate with each
other wirelessly. Fixtures can operate as
part of the zone’s group or as individual
units. For example, all lights within a zone
turn on to a minimum level if any part of
the zone is occupied, but only the lights
that sense occupancy brighten to full
output. Depending on occupant needs,
the maximum light level in a zone can be
tuned to low, medium or high. The controls change brightness levels gradually to
avoid distracting occupants.
The LEDs replaced fluorescent fixtures
in large open-office areas of both federal
buildings. LBNL researchers evaluated
energy savings, photometric measurements and occupants’ satisfaction.
Savings in Energy and Initial Cost
The surveys showed that occupants
were more satisfied with the new lighting’s brightness and illumination of work
surfaces. Compared to GSA’s average
energy usage intensity (EUI) of 3. 25 k Wh/
square foot/year, the LEDs with integrated ALC provided a savings of 69%.
Compared to the national EUI average
of 4.1 k Wh/square foot/year, the savings
Measured against the fluorescent
baseline, the wattage reduction from the
LED lamps alone accounted for 41% of
the GSA’s 69% savings, while the ALC accounted for the remaining 28%. The initial cost of the integrated ALC was lower
$0.47/square foot for integrated ALC vs.
$1/square foot for standalone.
Given the savings, the research estimates an incremental payback between
three and four years for renovations and
10 to 14 years for retrofits. Discounted lifecycle cost analysis that considers avoided
costs as well as savings creates a more
accurate picture of LED cost-effectiveness.
Longer-life LED lamps significantly reduce
maintenance costs, increasing total system
savings by about 25%. For GSA retrofits,
the average Savings to Investment Ratio
(SIR) is 1.4 (i.e. savings exceeds investment
by 40%), assuming the national average
utility rate of $.10/k Wh and the current
estimated cost of $3.29/square foot. For
renovations and new construction, the SIR
is 4. 4 (see graphs).
The GSA’s LED findings, as well as
Green Proving Ground findings on other
buildings systems, are available at