Summary
Robins Air Force Base is the home of Warner Robins Air Logistics Complex, the 78th Air Base Wing, and more than sixty other units that make up a vital part of the Air Force war-fighting team. It is the largest industrial complex in Georgia, employing a workforce of more than 24,000 civilians, contractors and military members.
Challenge
The 78th Civil Engineering Squadron, Robins Air Force Base, sought to improve lighting levels in the hangars and engine shop of the 116th Air Control Wing (ACW) of the Georgia Air National Guard. A total of four buildings, with about 500 thousand sq ft, were included in the work scope. Energy savings was very much a focus as the base worked to satisfy requirements outlined by the Air Force Strategic Facility Energy Plan to reduce energy purchased by the Air Force.
Solution
Referring to energy modeling data from audits previously conducted,
Robins AFB engineers identified areas where it would be easiest to
save energy. As the Air Force drew up its specifications for the
lighting upgrade, to increase efficiencies the improvements were
bundled with a geothermal project also being planned for the base. The
combined lighting/geothermal project was advertised for Robins AFB by
the General Services Administration (GSA), competitively bid under the
Federal Supply Schedules by three qualified firms and awarded to
Trane.
Trane’s proposal outlined a holistic approach,
which included day-lighting, dimmable fluorescent lamps and a
geothermal water source heat pump system, utilizing the adjacent lake
as the heat sink. The plan showed how the combined elements could
enhance energy savings for the base.
Optimal
illumination with renewable energy
Day-lighting, or Daylight Harvesting, is defined as a renewable
project by the Department of Energy. The day-lighting is designed to
provide up to 40 foot candles of illumination, reducing the number of
lighting fixtures required for optimal illumination and lowering
electricity consumption. Natural sunlight from over 300 active
tracking skylights provides the majority of the interior lighting
requirements during the day. Active tracking skylights differ from
passive skylights through the utilization of a solar-powered sunlight
tracking device in each skylight dome. This tracking device consists
of a mirror array which redirects three times more sunlight into the
workspace below, thereby reducing lighting power requirements.
Energy saving lighting upgrades
Inside the facility, light sensors control fluorescent lighting
levels based on skylight illumination. Lighting upgrades were
installed in buildings, hangars, the maintenance facility and the
warehouse operated by Air Guard, Air Force Reserve, 116th ACW and
Defense Logistics Agency (DLA) agencies. Over 800 Super T8 high bay
fixtures replaced metal halide lamps to bring lighting levels up to
required illumination standards and allow the facilities to operate
24x7. Delamping and relocation of lighting and BACnet®-enabled
lighting panels were installed to further improve energy savings and
operator safety, and meet change of mission requirements.
Quiet, efficient geothermal system
The Robins Billeting Area, consisting of four separate motel
and temporary housing buildings for base officers and VIPs, utilized
aging, noisy air-cooled chillers for cooling and natural gas boilers
for hot water heating and showers. Trane redesigned the mechanical
rooms in each building, installing efficient water source heat pumps,
controls, high efficiency boilers, hot water storage and pumps. The
completed hybrid geothermal system utilizes a local lake as its
renewable energy heat source in winter and heat sink in summer. The
system consists of 160-tons of geothermal heat pumps paired with
specially-designed stainless steel heat exchangers, which were placed
in the lake. A desuperheater was added to the system to utilize
rejected condenser heat to preheat the domestic hot water, resulting
in an 80 to 90 percent energy savings for water heating. The system
quietly and efficiently maintains comfortable indoor temperatures in
the billeting facilities, while helping Robins AFB to reduce energy
consumption and lower greenhouse gas emissions. A water spray fountain
was installed in the lake to cool it if necessary.
Additional value potential of new technologies
Trane is also evaluating several new technologies that could
potentially provide additional value for the installation. A
self-cleaning (air and surface) coating is being tested to determine
its ability to prolong light fixture emission due to the inhibition of
organic films that attach to the lamp and reflector. A hybrid PV panel
that generates power and hot water is also being monitored for panel
efficiency and total Btu generation in order to create a more
cost-effective renewable solar energy product.
Results
Taking a holistic approach, Trane worked with Robins AFB to implement day-lighting, lighting upgrades and geothermal projects. The improvements have enhanced lighting levels, provide a substantial energy savings, maintain indoor comfort and satisfy requirements of the AF Strategic Facility Energy Plan. Building Lifecycle Cost Analysis (BLCC) shows an ROI of less than ten years and a Savings to Investment Ratio (SIR) of over 2.0. Useful life of the geothermal and day-lighting systems is expected to be more than twenty years.
About Robins Air Force Base
Over 300 skylights installed at Robins AFB use solar-powered
sunlight tracking to redirect three times more sunlight into the
workspace below.
A hybrid geothermal system utilizes a
local lake as its renewable energy source and heat sink.
