Reducing Plug and Process Loads in Commercial Buildings

Managing commercial buildings is all about being more efficient and reducing costs, and one of the key areas to focus on is the plug and process loads (PPLs) of everyday devices and equipment. These loads, which account for about 28% of primary energy in US commercial buildings, are often overlooked in efforts to lower energy usage. However, with the help of research from the US National Renewable Energy Laboratory (NREL), commercial buildings can make significant strides in reducing energy costs and peak energy demand by optimizing PPLs.

Key Takeaways:

• NREL's research focuses on energy usage in buildings not associated with heating, ventilating, and air conditioning (HVAC), lighting, water heating, or other major end-use needs, and has identified opportunities in medical imaging equipment, elevators, computers, and other devices.
• The NREL team has developed a methodology to categorize energy use of the energy-intensive medical equipment without the challenges associated with extracting and processing individual scanner logs.
• The load duration curve method can identify non-productive modes and found that MRI scanners spent a significant amount of time (76-80%) in modes such as idle or low-power states.
• The team has also worked with hospitals and healthcare facilities to identify the correct metering setup to collect the data needed to develop the load duration curve method.
• The PPL team has developed a medical imaging equipment energy efficiency fact sheet for healthcare facility owners and operators, describing imaging equipment energy and operating cost reduction strategies.
• The NREL research team is tackling the challenge of PPLs from both sides to provide critical insights into optimizing PPLs, including developing new methodologies to improve the efficiency of equipment and innovative control strategies to ensure whole building systems are operating intelligently.
• The team's findings suggest that several pathways to support increased uptake of PPL efficiency and control in the commercial sector include developing and sharing more case studies and best practices, adding funding opportunities, gathering and sharing data on baseline PPL energy use, including PPLs in commercial energy codes, and promoting company efficiency goals.

Statistics:

• Energy is equal to average power multiplied by time, so to reduce energy usage from PPLs, either power or time used has to decrease.
• The U.S. Energy Information Administration (EIA) estimates PPLs consume about 28% of primary energy in US commercial buildings.
• MRI scanners consume up to 184 kWh per day in idle mode during weekends, which translates to more than $27 per day per machine (at $0.15/kWh) of operational cost.
• The team's research has identified opportunities for reducing energy costs in healthcare facilities through operational strategies.
• The PPL team will continue their research on MRIs, including applying the load duration curve method to MRI power data from several hospitals across the country, uncovering broader trends in MRI operation and energy behavior, and identifying additional opportunities for reducing energy costs in healthcare facilities.

Sources:

• US National Renewable Energy Laboratory (NREL)
• US Energy Information Administration (EIA)
• University of California (UC) Davis Health
• University of Michigan Medicine