Large commercial buildings can often go years without maintenance being performed on the controls that are designed to keep the building running smoothly. Often, these controls aren’t used to their full potential. When these controls go without maintenance and are not used to their full potential, the commercial building often has a high power bill.
A new report found that if commercial buildings use their controls to their full potential nationwide, the U.S. energy consumption could be lowered by the equivalent of the energy currently used by 12 to 15 million Americans.
The report studies 34 energy efficiency measures, most of which rely on building controls, and how they could affect energy use in commercial buildings like stores, offices and schools. Researchers at the Department of Energy’s Pacific Northwest National Laboratory found these measures could cut annual commercial building energy use by 29 percent. This would result in between 4 to 5 quadrillion British Thermal Units in national energy savings. This is about 4 to 5 percent of the energy consumed nationwide.
"Most large commercial buildings are already equipped with building automation systems that deploy controls to manage building energy use," said 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. Our research found significant nationwide energy savings are possible if all U.S. commercial building owners periodically looked for and corrected operational problems such as air-conditioning systems running too long."
This report has a detailed national benefit analysis of multiple energy efficiency measures to address building operational problems, which can be corrected with little effort. Unlike other practices, which require expensive new technologies, most of the measures that were evaluated improve energy efficiency by enabling the equipment that is already installed in the building.
About 20 percent of America’s total energy use is from powering commercial buildings. About 15 percent of U.S. commercial buildings have automation systems that deploy controls like sensors that turn on lights or heat a room only when it is occupied. By helping commercial buildings take advantage of these controls, it could lower America’s energy consumption.
Combining individual measures can increase energy savings, so researchers also estimated the impacts of packaging energy efficiency measures together. PNNL designed packages of combined measures based on the needs of three building conditions: buildings already efficient with little room for improvement, inefficient buildings with a lot of room for improvement and buildings that land in the middle.
PNNL used computer models of nine commercial buildings and extrapolated them to represent five similar buildings so researchers could evaluate energy use in 14 building types. The researchers used these prototypes with DOE’s EnergyPlus building software. This calculated potential energy used based on local weather and whatever energy efficiency measures were applied.
Of the efficiency measures studied, the greatest energy-saving potential nationwide is as follows. Lowering daytime temperature set points for heating, increasing them for cooling and lowering nighttime heating set points resulted in about an 8 percent reduction. Reducing minimum rate for air to flow through variable-air-volume boxes resulted in about a 7 percent reduction. Limiting heating and cooling when the building is occupied resulted in about a 6 percent reduction.
Some building types were found to have the potential to save more. These buildings were: secondary schools could save about 49 percent more, and standalone retail stores and auto dealerships could save about 41 percent.
It was also found that inefficient buildings have the greatest potential for energy saving. Inefficient buildings have the potential to save 30 to 59 percent, typical buildings 25 to 56 percent and efficient buildings 4 to 19 percent. By increasing the use of automation systems that buildings are already equipped with, many commercial buildings across the U.S. can increase their energy efficiency.
To learn more about this research, click here.