As COVID-19 and its physical and economic impacts reshape industries, facility managers and building operators are looking at how to most efficiently run existing commercial and industrial spaces that may be used very differently in the future. Not knowing what a post-pandemic world looks like, many companies have already given their employees the option of working from home permanently. Others are proposing a mixed office and home schedule. Retailers may continue limiting the number of customers to ensure safety. While there are many uncertainties, it’s a safe bet that many commercial buildings could have far fewer daily occupants even after the pandemic subsides.
So how do building operators conserve resources when occupancy may drop more than 50%? One way is to consider installing a Power Drive System (PDS) on commercial pumps, fans, compressors and other motor-driven products that heat, cool and provide water and wastewater services within these buildings.
While adding variable speed capability in commercial buildings is not a new idea, a new analysis shows major energy and cost savings are available by pairing those products with a PDS, regardless of a pump’s load variability. A PDS combines an electric motor, adjustable speed controls and sensors that provide feedback to the equipment, allowing the equipment to slow down or speed up to meet current demand. This idea and the added flexibility a PDS can provide may be even more important as we move forward in uncertain times.
Overlooked opportunity
The use of these products have grown over the years, but they are most often applied to variable load systems. New research led by the National Electric Manufacturers Association (NEMA) and the Northwest Energy Efficiency Alliance (NEEA) is among the first to provide energy savings data on the impact of PDSs on constant load systems or systems which require the same amount of flow throughout operation.
Using operational data, the research found:
- Energy use dropped by 23% when PDSs were used with constant load systems; and
- Energy use dropped by 43% when PDSs were applied to variable load systems.
The data presents a clear opportunity for owners and operators of commercial and industrial facilities to dramatically cut their energy spending.
Until now, there has been a lack of data on the effect PDSs have on constant load systems, which has likely kept organizations from investing in a PDS and prevented them from reaping the full benefit of better system control.
The NEMA and NEEA research also found the payback period, or the amount of time it takes to recover the cost of investing in a PDS, was 10 months for a constant load system and four months for a variable load system.
The research, which focused on pumps, shows variable torque applications, which are typical in commercial building applications, are considered the best candidates for PDS installation with motor speed cut in half, leading to a reduction in energy use of nearly 88%.
The analysis also explores the difference in savings for constant and variable loads for four commercial pumping applications: Cooling tower, heating, pressure boost and cooling. The research found that while the savings potential is larger for variable load pumps, every application sees energy savings from PDS installation on constant load pumps.
Non-energy benefits
The full benefit of utilizing a PDS goes beyond cutting energy use and costs. The analysis also found these non-energy benefits of installing a PDS:
- Less maintenance, thanks to less equipment wear when starting and operating motors and motor-driven equipment;
- Process improvements and improved control, which can have meaningful impacts on overall system efficiency (e.g., ensuring appropriate return water temperatures to a condensing boiler) and better respond to changes in system load due to unexpected increases or decreases in demand; and
- System connectivity and visibility, which allow operators to better maintain efficient equipment and system performance, and may allow them to do so remotely.
According to ENERGY STAR, energy efficiency investments can also pay for themselves by increasing the value of buildings and industrial sites. Studies from the U.S. Department of Energy have shown efficient buildings and industrial plants have lower operating costs and efficient commercial real estate properties command higher rents with tenants.
Beyond pumps
While the new NEEA and NEMA study focuses on pumps, it is believed that the concepts and projections in the report can apply to fans and compressors as well. The energy benefits for a PDS in fan and compressor applications may be smaller since there are already some existing control methods that help decrease load at reduced flow rates. But, the addition of the non-energy benefits mentioned above, including less maintenance, are also important to consider.
Energy impact of commercial, industrial sectors
This study and the data it has produced is of critical importance, whether or not it is viewed through the lens of COVID-19. The DOE reports commercial and industrial buildings, from factories to schools to supermarkets, account for nearly half of all energy consumption in the U.S., at a cost of more than $200 billion per year. That’s more than any other sector of the economy. Out of that energy, 30% or more is wasted through inefficiencies.
Considering motor driven products like pumps use up about 25% of all commercial energy, this new research shows the huge potential for energy savings by utilizing a PDS. Greater use of PDSs, along with other efficiency improvements, means organizations can save more energy and money and have a greater impact on protecting the environment.
Visit NEEA’s resources and reports page to read the full analysis on PDSs. You’ll also find other research on emerging technologies that may help inform energy efficiency projects.
