Op-ed: The benefits of submetering and learning how energy is used
In its ongoing efforts to help control increasing energy costs while reducing environmental impacts, American University’s Energy & Engineering team (E&E) incorporates submetering to its practices.
Submetering is the measurement of energy use in buildings, systems and equipment to allow for a better understanding of how, when and where energy is consumed. Submetering buildings on campus can make a substantial difference in utility costs, carbon footprint management and overall energy practices. In fact, the U.S. Environmental Protection Agency (EPA) estimates that metering can help drive an average savings of five to 10 percent on utility bills.
However, targeting facilities that waste energy becomes challenging with a campus-wide total of 57 utility meters that gauge electricity, water, natural gas and thermal consumption, some serving multiple buildings.To obtain more detailed energy usage information, the E&E team installed electric submeters throughout campus. Since 40 percent of energy consumed and greenhouse gas emissions come from buildings, targeting energy usage in buildings is the best energy management practice.
Submeters provide the detailed data and trending necessary for AU’s energy analysts, engineers and management to:
- Benchmark campus buildings’ energy use against national databases
- Measure results of energy conservation measures and projects
- Identify equipment running unnecessarily in unoccupied buildings and during “peak rate” periods
- Identify demand peaks, allowing Facilities Management to make necessary adjustments to better manage electricity usage reduce peak demand cost
- Identify discrepancies with utility bills by comparing data
- Detect system failures quickly
- Identify and prioritize opportunities for energy projects.
By analyzing data and energy use collected from submeters, the E&E team can see when an individual building’s systems or equipment use unusually high amounts of energy in small intervals. Submetering makes it easier to figure out what is consuming the most energy and to see abnormal peaks in usage. It can identify equipment or systems that need to be repaired, maintained, or replaced. Energy projects also can be better prioritized based on which buildings are in higher need of upgrades rather than through the use of traditional meters which capture the entire campus’ usage.
Initially, the E&E team only used submeters to monitor electrical usage. However since 2012, it has been expanded to include thermal (heating and cooling) energy usage as well. The closer scrutiny of energy usage resulted in the E&E team uncovering savings opportunities. For example, heating and cooling systems now only operate at full capacity during times of building occupancy. During off-hours, on-campus systems run at lower settings. Before the new programming, the McKinley Building consumed about 358 kilowatts between 2 and 7 a.m. when the building was not being used. Now, the building uses about 155 kilowatts during the same time frame. The amount of kilowatts used has been reduced by more 55 percent.
Through data from submetering, the E&E has found additional ways to cut waste and emissions for the University’s Utility and Energy Master Plan. Future energy-saving projects and pilots are in the works to achieve AU’s goal of reducing energy consumption by one to two percent annually.
Ruby Tavernier is the Utilities Outreach Program Leader at American University.