In retail environments and offices, the concentration and performance of workers has been proven to be superior to those where only artificial light is present.

There is compelling evidence that shoppers in retail environments generally stay longer and spend more where there are high levels of natural daylight – and the performance of retail workers has also been proven to be superior to those where only artificial light is present.

There is a well documented correlation between the presence of roof lights and retail sales. This can be attributed to a greater sense of wellbeing in these stores, as well as improved presentation of products.

‘Daylight & Retail Sales’ is a detailed technical report commissioned by the California Energy Commission. This was undertaken by Heschong Mahone Group (now part of TRC, the highly respected energy efficiency consulting business) as long ago as 2003 – yet it still remains the most frequently quoted research document on this subject.

The document presents evidence that a chain retailer experiences higher sales in daylit
stores than in similar non-daylit stores. Statistical models, using up to 50 explanatory variables, examine the relationship between average monthly sales levels and the presence of daylight in the stores, while simultaneously controlling for more traditional explanatory variables such as size and age of the store, amount of parking, local neighborhood demographics, number of competitors, and other store characteristics.

The study included 73 store locations in California, of which 24 stores were daylit primarily by diffusing skylights. Statistical regression models found that increased annual hours of useful daylight per store were strongly associated with increased sales

The report can be downloaded at: