Easy Steps Could Lead to Big Energy Savings

A new report finds that if commercial buildings fully used controls nationwide, the U.S. could cut its energy consumption by the equivalent of what is currently used by 12 to 15 million Americans.

The report from the Energy Department's Pacific Northwest National Laboratory looks at how 34 different energy efficiency measures, most of which rely on various building controls, could affect energy use in commercial buildings such as stores, offices, and schools.

Researchers found the measures could cut annual commercial building energy use by an average of 29%. Doing so would result in between 4 to 5 quadrillion British thermal units in national energy savings, which is about 4-5% of the energy consumed nationwide.

PNNL researchers Srinivas Katipamula (right) and Nick Fernandez (left) examining a control box for a commercial building’s heating and cooling system"Most large commercial buildings are already equipped with building automation systems that deploy controls to manage building energy use," says report co-author and PNNL engineer Srinivas Katipamula. "But those controls often aren't properly programmed and are allowed to deteriorate over time, creating unnecessarily large power bills.

(Read "Big Buildings More Likely to Use Lighting Strategies: Report.")

The report offers a detailed national benefit analysis of multiple energy efficiency measures to address building operational problems. Many of these problems can be corrected with little effort, the report says. Unlike other practices that require expensive new technologies, most of the measures evaluated improve energy efficiency by enabling already-installed equipment to work better.

Roughly 20% of America's total energy use goes toward powering commercial buildings. And about 15% of U.S. commercial buildings have building automation systems that deploy controls, such as sensors that turn on lights or heating a room only when it's occupied. As a result, helping commercial buildings better use their controls could cut America's overall energy consumption.

Among the energy efficiency measures examined in the report are:

• Fixing broken sensors that read temperatures and other measurements
• Turning off power-using devices like printers and monitors when a room isn't occupied
• Dimming lights in areas with natural lighting

Because combining individual measures can increase energy savings, the researchers also estimated the impacts of packaging energy efficiency measures together. PNNL designed packages of combined measures based on the needs of three different building conditions: buildings already efficient and with little room for improvement, inefficient buildings with a lot of room for improvement, and typical buildings "in the middle."

PNNL used computer models of nine prototypical commercial buildings, and extrapolated them to represent five other, similar buildings so it could evaluate energy use in a total of 14 building types. The research team used these prototypical building models with DOE's EnergyPlus building software, which calculated potential energy use given local weather and whichever energy efficiency measures were applied.

Of the individual efficiency measures studied, those with the greatest energy-saving potential nationwide were:

• Lowering daytime temperature setpoints for heating, increasing them for cooling, and lowering nighttime heating setpoints: about 8% reduction
• Reducing the minimum rate for air to flow through a variable-air volume boxes: about 7% reduction
• Limiting heating and cooling to when building is most likely to be occupied: about 6% reduction

Alhough the study found all commercial buildings across all climates could have an average total energy savings of 29%, some building types were found to have the potential to save more, such as:

• Secondary schools: about 49%
• Standalone retail stores & auto dealerships: about 41%

Researchers found that inefficient buildings have the greatest potential to save energy, an expected finding. After estimating how common each building condition is in the U.S., researchers found combined efficiency measure packages have the following potential national energy saving ranges:

• Inefficient buildings: 30-59%
• Typical buildings: 26-56%
• Efficient buildings: 4-19%

The Department of Energy's Office of Energy Efficiency and Renewable Energy funded this research.