Energy Systems Optimization for Small Retail
Retail stores, known for their extravagant lighting displays, are big energy users, consuming nearly 20 percent of all energy used by U.S. commercial buildings. But the news on the street is that when it comes to energy, flash no longer sells. Retailers from Crate and Barrel to Walmart are adopting new energy initiatives to reduce their stores’ energy consumption and lead the sustainable retail revolution.
What sets retail stores apart from other types of businesses are their long operating hours and their often high occupancy rate in the evenings. In most stores, electric lighting accounts for 22 percent of total building energy use. But with energy-efficient lighting retrofits, you can save upwards of 30 to 50 percent of lighting energy as well as 10 to 20 percent of cooling energy. Add intelligent controls with sensors at each fixture and you’ll see even greater savings. Here’s a good rule of thumb to get you motivated: According to the U.S. small business administration, a 10 percent reduction in energy costs for the average full-line discount retailer can boost net profit margins by as much as 1.55 percent and sales per square foot by $25.
So why aren’t more retailers immediately improving the lighting systems in their stores? While the savings from a lighting retrofit can be significant, a single expenditure that is not integrated with other improvements might seem too costly for your business’s bottom line. The right timing, careful planning and an integrated approach can address this challenge and make a deep energy retrofit not only possible but also profitable.
Here are four recommendations from the National Renewable Energy Laboratory (NREL) that have been shown to result in a 50 percent net energy savings for all cases and in all climate zones. (A five-year total life cycle cost was the defining economic criteria.) While these recommendations are specific to medium box retail stores—defined as a 50,000 square foot, one-story rectangular building with a 1.25 aspect ratio—they also make sense for smaller stores too.
Place daylighting sensors and controls in all zones with side- or top-lighting.
Reduce lighting power density by 40 percent, and use occupancy sensors in the active storage, office, lounge, restroom and electrical/mechanical spaces.
Shade all windows on the façade. Reduce the façade glazing by 20 percent.
Install efficient fans in all rooftop HVAC units.
These measures lend themselves easily to quantifiable metrics, but NREL also recommends exploring alternative measures such as HVAC systems that use ground source heat pumps, packaged variable air volume systems and radiant heating and cooling; solar thermal technologies for service water heating and space conditioning; direct and indirect evaporative cooling; decreased pressure drop via improved duct design; and state- or utility-specific rebate programs for photovoltaic. Remember, these ideas are only starting points—each space presents its own specific needs, as well as solutions.