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The Benefits of Daylighting

Scientific research demonstrates that up to a 40% increase in retail sales can be achieved with well-designed natural interior daylight in the right retail environment.

What popularized skylights for large chain retailers was the extraordinary sales increase that Walmart achieved when they designed their first energy-efficient model store in Lawrence, Kansas, in 1993. Specially designed skylights were installed on half of the store’s rooftop. The SKUs located under the skylights sold better than those under fluorescent electric lighting. To validate the increased sales results of natural lighting, Walmart swapped merchandise from one side of the store to the other and noted the same sales increase for the merchandise moved to the daylit zone.

Then, in a 1999 landmark study, PG&E commissioned Heschong Mahone Group (HMG, now part of TRC Companies) to investigate the effects of skylights on retail sales. Over an 18-month period, HMG analyzed the sales performance of a chain retailer’s 108 outlet stores, two-thirds of which had skylights and one third of which had none. The results establish a statistically compelling connection between skylighting and retail sales. In fact, apart from store hours, skylights were found to be the best predictor of sales. The report found that the non-skylit stores would likely have seen 40% higher sales with the addition of skylights, with a probable range of 31%-49%.

Research by Eneref Institute has determined that today, the pivotal sales opportunity lies in the supermarket sector. Everything from fresh fruit to soda bottles looks better under skylights because daylight accurately renders all wavelengths of light within the visible color spectrum. When merchandise is illuminated with the broad spectrum of sunlight, their true colors are reflected with an even intensity, making them more appealing to the human eye.

Competition for millennials’ wallets from online sales and delivery/pick-up services is threatening traditional grocery stores. Retailers who act aggressively to mitigate climate change can appeal to millennials, who strongly believe that climate change is now upon us. Skylights offer retailers a net-zero energy resource, an attractive selling point to millennials vigilant about mitigating climate change. The 2018 UN Intergovernmental Panel on Climate Change (IPCC) found that to prevent the worst consequences of climate change from occurring as soon as 2040, carbon dioxide emissions must plunge to less than half of what they are today — within the next 10 years. That’s why utilizing natural interior daylight is critical: unlike LED electric lighting, daylight uses no energy and produces no carbon emissions.

While retailers need to engage millennials for long-term viability, their older customers also need better lighting. According to the Illuminating Engineering Society, people 55 and older require 2.3 times more light for the same visual acuity as 25-year-olds. Well-managed daylight can significantly raise interior light levels without glare, bringing up to 200-ft. candles of full-spectrum lighting into a building — which would be costly to achieve with electric lighting.

Eneref Institute has found that the key benefits of daylighting for retailers also include increased foot traffic because stores with natural illumination were reported to feel more inviting by customers interviewed for this Eneref Report. Illuminating checkout counters with natural daylight made customers feel more at ease. The same tactic can be used to encourage shoppers to interact with salespeople, who seem more approachable under natural light. By creating a more pleasant shopping experience, retailers will attract more customers and increase sales.

In the Eneref Institute survey, architects reported that they specify natural daylight for many reasons: improved aesthetics, more pleasant psychological feelings, enhanced quality of light, elevated visual comfort and better color balance. One architect who works for a major retail chain said that he “looks to bring in an abundance of visible sunlight into the space, even when the sun is low on the horizon.” The architect explained that he specified Velux Dynamic Domes in a recent project for that very reason, though he also noted that today several high-quality commercial skylights are available on the market.

Lighting buildings with natural interior daylight can potentially provide a significant increase in retail sales and, studies show, employee productivity. By using natural daylight, all retailers, and especially supermarkets, have a unique opportunity for a triple play: tackle climate change, shrink energy costs and boost sales—all at the same time.

Monica Alpizar is associate editor at Eneref Institute, a global research advocacy organization with offices in the United States, Asia, South America, Africa, and Europe.
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