An Energy-Efficient Future for Department of Defense Facilities

October 13th 2011
Department of Defense insignia

Teaming up to fight against escalating energy costs, the Department of Defense, Lawrence Berkeley National Laboratory (Berkeley Lab), and Philips Corporation are demonstrating advanced energy-efficient lighting controls technologies in Fort Irwin, California.

"The purpose of this study is to demonstrate that these technologies work in typical applications and buildings at Fort Irwin, and to provide the technical experience and data to support scaling up these energy-efficient systems at Department of Defense facilities throughout the U.S.," says Francis Rubinstein, a scientist in Berkeley Lab's Environmental Energy Technologies Division.

The nation's military is looking to apply advanced energy-efficient technologies in its facilities to help reduce its energy costs, and the nation's dependence on external sources for its energy. The nation's military has long been a testbed and proving ground for technological innovation—DoD-sponsored research led to the integrated circuit and the Internet among many others.

At a speech in Virginia, Deputy Secretary of Defense William J. Lynn III recently said, "… in facilities, where the buildings and systems we use are the same as in commercial industry, any innovations we achieve in-house can directly transfer to the rest of the economy. And because of our size and ability to serve as a sophisticated first user and early customer, the military can jump-start the broader commercial adoption of innovative energy technologies.

"Our Installation Energy Test Bed program aims to do just this. Some of the technologies we are demonstrating are simple, like advanced lighting systems that calibrate their output to the amount of available daylight and use occupancy sensors to turn lights on-and-off."

The Environmental Security Technology Certification Program is funding the work. ESTCP is DoD's environmental technology demonstration and validation program. The Program's goal is to identify and demonstrate cost-effective technologies that address DoD's highest priority environmental requirements.

Fort Irwin, California's DoD Lighting Testbed

Fort Irwin staff members are working with Rubinstein and Abby Enscoe of EETD, and Philips, to demonstrate and evaluate three advanced, energy-efficient lighting systems in military buildings. Two of the systems use wireless technology for lighting control.

DoD manages more than 300,000 structures and 2.2 billion square feet of space on its installations. The Department spends $4 billion a year just to buy the energy needed to run its facilities.

The research team estimates that in large military installations, lighting typically represents around 28% and cooling represents 33% of the total electrical energy used. They write: "At present, nearly 50% of the lighting energy consumed throughout DoD facilities is lost because their lighting systems are either outdated and/or inadequately controlled."

At Fort Irwin, an Army training facility in the Mojave desert near Barstow, California, a team composed of Enscoe, Rubinstein, Philips, lighting experts Maulin Patel, Satyen Mukherjee, Matt Helm, and Dagnachew Birru, and Fort Irwin facilities managers have installed advanced lighting systems in three buildings, and are carefully monitoring and recording their use patterns and energy savings.

"Different buildings and use patterns require different retrofit and control strategies," says Enscoe. "One of the purposes of this demonstration is to get experience with how well different lighting control systems perform in different types of buildings."

Each building has a different system adapted for its building type. In a building with large south-facing windows and plenty of available daylight, they installed a Hybrid Integrated Lighting and Daylight Control system (Hybrid ILDC), which maximizes the use of daylight, and improves visual comfort using electric lights and motorized blinds that are automatically controlled.

They are testing a variety of control approaches—such as occupancy sensing, personal dimming controls, and automated glare avoidance—to see which control sequences provide the best combination of energy savings and user comfort. The system uses wireless technology to connect sensors and motorized blinds within a lighting zone, and wired connectivity to connect zones (thus, a hybrid) so that the control system can be deployed throughout a building.

In a building with a hard ceiling and lower daylight levels, they installed a fully wireless system, called Occuswitch, which automatically turns lights OFF when a space is unoccupied, and dims the electric lights in response to available daylight. Occuswitch uses wireless communication between sensors and switches, which reduces retrofit costs, particularly in areas with hard ceilings.

In a headquarters building with a variety of different use types, they installed the wired Philips Networked Lighting Control System (PNLCS). This building-wide wired lighting control system includes personalized dimming controls, automatic scheduling, occupancy sensing, daylight harvesting, and distributed control—lighting in different zones can be controlled from different locations through different control devices. PNLCS can work with existing building management systems including HVAC controls.

In each system, building occupants now have the ability to set their preferred light levels, which was not possible to do before the new controls were installed. "Individual lighting control has been found to improve occupant satisfaction," says Enscoe. "The win-win of saving energy and improving occupant control is one of the strong arguments for installing controls. "

Coupling Lighting and HVAC Control

To better understand how the hybrid system can save air conditioning and heating energy use, another EETD team, led by Vladimir Bazjanac, is using the EnergyPlus building energy simulation software to model the building in which it is installed. This will help the project team understand how to optimize the control system and the motorized blinds to minimize both air conditioning and lighting energy use. By reducing solar heat gain into the building, the system can reduce the need for air conditioning, but still allow in sufficient daylight to minimize the use of electric lights.

Early Results Show Substantial Energy Savings

The results so far have been promising. Three months of post-retrofit energy data show that the hybrid system resulted in estimated annual energy savings of 28% compared to the measured baseline energy use before the retrofit. Compared to the baseline energy use of a "code building" with an old lighting system operating 10 hours per weekday, the estimated annual energy savings was 79%. The baseline code building represents buildings with existing DoD lighting systems that were installed more than 20 years ago and are in need of a retrofit. It provides a rough estimate of the magnitude of potential lighting energy savings throughout DoD buildings with the same type of older lighting systems.

The wireless Occuswitch system, which turns off lights automatically when a space is unoccupied and dims electric lights in daylit areas, also resulted in energy savings. In this building, the team changed the configuration of lights so that they provide better, more even lighting levels for workers, and meet lighting codes.

Adjusting for the changed configuration, three months of data show that the control system reduced lighting energy use in perimeter offices 34 percent, and 16 percent in central office areas, for an average of 22 percent savings. Compared to the code baseline, the system saved 62 percent of lighting energy use.

The PNLCS system has also performed well. As in the Occuswitch building, an adjusted baseline was calculated to eliminate the effect of changes in the installed lighting and isolate controls savings. After three months of data, the control system has reduced lighting energy by 18% compared to this baseline, and by 40% compared to the code baseline. The system has also given occupants much more ability to control light levels in the building.

"We have anecdotal evidence that, on balance, building occupants like the new lighting systems," says Enscoe. "We have also learned that details matter—the specific control algorithms and installation details make a big difference."

The monitoring of the buildings will continue through the end of 2011. DoD will look at the results, and develop a plan for scaling up the installation of energy-saving systems that have been shown to be cost-effective.

Rubinstein is confident that the wireless systems can be scaled up cost effectively. "It is expensive to install wires in ceilings, but less expensive to put sensors into the lighting systems. Energy service companies know how to add wired control systems when necessary, but the wireless approach brings an additional cost advantage to a lighting improvement program."