When visiting a retail store, customers are looking for a pleasant shopping experience. They want to look vibrant in the clothing and cosmetics sections, they want the produce to look fresh and delicious, and they want to be able to find what they are looking for. Lighting products attractively and ensuring customers can find the products they are looking for are critical to increased sales for the retailer. For many years, retail stores have relied on electric lighting, oftentimes over-lighting products and unintentionally making the products difficult to see due to the poor quality of the light.
Retail stores are big energy users, consuming nearly 20 percent of all energy used by U.S. commercial buildings. In a typical retail store, electric lighting accounts for 22 percent of total building energy use. Lighting retrofits can save upwards of 30 to 50 percent of lighting energy as well as 10 to 20 percent of cooling energy. Intelligent controls with sensors at each fixture can see even greater savings.
Retrofitting box retail stores, with their expansive floors and open plans, has the potential to reduce lighting and cooling costs dramatically across their entire portfolio. Big box stores are often easily daylit with simple skylights, an inexpensive and effective solution.
Providing daylighting can meet customers’ needs while saving energy and improving the appearance of the store—the store feels brighter, customers can more easily evaluate products, and products are perceived as more attractive, often increasing product sales for the retailers.
Recently the U.S. Department of Energy worked with Whole Foods to find real solutions to energy efficiency in its stores. The goal was to not only achieve a high-performance building but to analyze and test solutions that could be replicated in other stores. The store in Raleigh, North Carolina, achieved total energy savings of 25 percent over a baseline store and almost 50 percent savings in lighting energy.
Timing is the key to more and better daylighting
So why aren’t more retail big box chains adding daylighting into their stores? The opportunity for energy savings from a lighting retrofit may appear to be significant but it is often unclear when to intervene to make the retrofit cost effective. A single expenditure that is not coordinated with other improvements can be costly and have an unacceptable payback period. Right-timing and planning can address these concerns and make a deep energy retrofit not only possible but also profitable.
Timing a lighting retrofit with major planned capital investments such as a roof replacement, equipment replacement, and non-energy-related renovations such as branding upgrades is critical to realizing maximum energy savings without leaving efficiency opportunities on the table. When a roof replacement or a branding upgrade is being considered, redesigning the electric lighting layout and adding skylights makes sense. With these major investments already happening, costs associated with moving around lighting fixtures and cutting holes in the roof can be minimized.
Re-designing electric lighting layout with lighter interior finishes to accommodate a larger spacing between fixtures and acceptable target illumination levels can also reduce the amount of fixtures that need replacing and lower yearly maintenance costs. Current energy codes allow for 1.6 watts per square foot for retail environments and industry standards such as ASHRAE 90.1 and IECC recommend 1.4 watts per square foot, but finding a balanced approach by lowering illumination values by 25 percent and energy use by 25–40 percent will optimize the lighting and energy conditions. Adding skylights can further reduce this energy use from electric lighting by installing controls to turn electric lights off during daylit hours and unoccupied times.
Many retailers are now retrofitting their stores for efficiency to meet energy targets or goals. Walgreens recently installed high-performance skylights and replaced their fixtures with LEDs in a pilot project in Arizona to meet targets of the Better Buildings Challenge. The store is anticipating 43 percent energy and maintenance savings from electric lighting energy use with these measures alone.
Timing a retrofit with mechanical upgrades or equipment replacement can have significant savings if other efficiency measures are also considered during this time. Considering reducing loads associated with envelope, plug loads, and electric lighting can significantly reduce the size of the equipment needed or could eliminate a component of mechanical equipment, avoiding capital costs that would otherwise be invested in the mechanical system upgrade. These savings can in turn be used to pay for other efficiency measures such as envelope insulation or adding skylights. When mechanical systems are being replaced, raising ceilings can reduce the amount of skylights needed to meet illumination levels (often about 4 percent of floor area) and eliminates the cost of replacing the dropped ceiling.
Understanding the synergies between building systems and planning ahead for energy efficiency interventions will guarantee that opportunities are not left on the table and that maximum efficiency of a building can still be achieved in the future. In the competitive retail world, adding daylight may offer the critical business advantage retail stores need.
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