By Erin Rigik, Senior Editor
Convenience stores are increasingly looking to energy management systems to help them better control their energy efficiency.
For instance, Kum & Go is known for its commitment to energy efficiency. In 2010, the chain started building 5,000 square-foot stores that feature environmentally-friendly innovations, such as sustainable materials, reflective concrete, a reflective roof, LED lighting, water-saving fixtures and high-efficiency equipment.
The family-owned company operates more than 430 convenience stores in 11 states, and continues to grow. Each new build is designed, constructed and submitted for LEED (Leadership in Energy and Environmental Design) certification. Kum & Go currently has 82 LEED-certified stores, with 23 additional stores under review for LEED certification. The 100th LEED certified store is expected to open in early 2015.
To reach those standards, some 95% of Kum & Go’s lighting is provided by LEDs—inside and outside the store. In addition to the LEDs, Kum & Go installs daylighting devices that use daylight to help illuminate interior spaces when possible, further conserving energy. The chain also recovers heat from exhaust air before it is removed from the building and uses it to heat the cold, incoming air. It uses low-flow plumbing fixtures and therefore uses 35% less water than typical stores. All this efficiency not only resonates with the chain’s eco-conscious demographic—it also helps Kum & Go’s bottom line.
Sara Kurovski, manager of sustainability at Kum & Go, noted that Kum & Go uses energy modeling and commissioning to evaluate the efficiency of each new build.
Energy modeling is a process that examines proposed designs for a new building and projects how much energy is likely to be used once the structure is built and operational, and also predicts the return on investment (ROI) of potential energy efficiency solutions for that location.
Once a new store is up and running, Kum & Go relies on an energy monitoring system through which all energy devices are connected—the system measures lighting, HVAC, refrigeration, equipment and receptacles—allowing the corporate office to see via a dashboard how much energy is being used and where. The stores’ actual energy usage is turning out to be less than predicted, however the chain continues to gather data as new stores are brought online for monitoring. The modeling and monitoring help Kum & Go target its energy efficiency initiatives in order to be most successful.
“Our engineers learned through our energy modeling that our highest energy usage was in areas we least expected,” Kurovski said. “Going in to the energy modeling, it was assumed our refrigeration units would be among the systems consuming the most energy in our stores, but Kum & Go is at the point where our refrigeration is actually really efficient.”
Kum & Go already uses a centralized refrigeration system, for example, that saves energy by using more advanced controls and compressor unloading.
Instead, energy modeling showed Kum & Go that many separate pieces of equipment combined equaled its largest energy consumption, including ovens and roller grills. That information has allowed Kum & Go to better target its efficiency plans.
“We are refocusing our attention on specific equipment to see how we can make those areas much more energy efficient,” Kurovski said. “One of the benefits of energy modeling is that you have the data in front of you telling you where you can turn your attention to have the highest impact on efficiency, as well as the best return on investment.”
Of course, being a 24-hour provider of fresh, hot foodservice items requires equipment to run all day and all night—simply turning off the machines for a while isn’t an option. “We’ll look at more energy efficient equipment, different vendors and other options that might exist,” Kurovski said.
Since adding energy modeling, Kum & Go has seen between 28-33% energy savings depending on store location and climate.
Meanwhile, the energy control or monitoring system displays what is happening with energy in real time. If an employee leaves the lights on overnight in a store that isn’t open 24 hours or there is an issue with a refrigeration unit being off, headquarters can see that in real time and call the store for clarification.
Selecting A System
Before selecting an energy management system, ensure the equipment you are using is as efficient as possible.
“There are various grades of energy management systems for retailers—from low cost systems that turn equipment on and off to more complex systems that offer feedback, bringing measurements in and making choices. But feedback isn’t free. Your choice could be related to the pay structure you’re under with your utility. Companies should not be making this decision without recognizing how they’re paying their electric bill,” said Thomas Reddoch, a senior technical executive for power delivery & utilization at the Electric Power Research Institute (EPRI).
One of the key determinants in what type of system is best for your chain is the rate structure used by your utility to classify how electricity is sold to your chain. There are three types:
Energy. This rate measures kilowatt hours (kWh) used in a 30-day period. This is a straight energy charge. To reduce the bill one must reduce energy consumption. One way is using motion detectors and dimmable lights when store areas are not in use.
Energy & Demand. This bases your bill off a combination of your peak usage and an energy charge. If you used the most kilowatts on the second day of the month from noon to 1 p.m., your rate will be based off of that one hour of peak usage—even if the rest of your energy usage for the month is much lower. You want to be monitoring total usage in the facility to keep peak usage low and turn things off when you can. Many times this is achieved by making sure refrigeration and air conditioning trade off as to when they are running. Many energy management systems are bought for this purpose.
Time-oF-Use Rate. Here there are a set of hours where you pay a designated energy rate. “For example, if you use electricity from 10 a.m. -7 p.m. you pay 12 cents a kWh, and after that it’s six cents a kWh. Now it’s a shift loading strategy. What can I defer during expensive periods to less expensive periods? At 5 p.m. what can I delay until at 7:01? Maybe you can turn your freezer off for two hours and turn it back on at 7:01 p.m. Here you need a smarter energy management system,” Reddoch said.
Trends On The Horizon
The next trend in lighting is a smart light. “We’ve had this technology for some time in cars where an indicator light tells us our coolant is low,” Reddoch said. “LEDs have an electronic ballast that drives the light, so if something is not right we have the ability to get early warning indicators.”
People have studied the failure modes of the electronics that drive the light and there is a whole field of study called signature analysis. “With people, if our temperature is 98.6, we’re fine, but if it’s lower, something is not right and if it is higher something else is not right,” Reddoch said. “So in a light, we look for the direct signature of what a device should look like, and what indicators tell us something is going wrong, such as heat or a vibration—things we can measure. When we make devices smart that means doing diagnostics and recognizing when this device is deviating from good signature.”
The most inexpensive option is to put a sensing device on the light when it is being manufactured. Retrofitting the component is very expensive. “There has been a lot of discussion on what can we embed in the light when we build it. The key is to put some sort of computer chip into the device and add sensors to detect problems,” Reddoch said.
An energy management system or a facility management system would then be alerted indicating a light might need maintenance soon. This is a tremendous value to retailers.