Daylighting and Electric Lighting Integration in the Retail Sector

Abstract: The retail sector represents 11% of the GDP and employs 15% of the workforce in the European Union. To tackle growth of e-commerce, physical retail stores need to be reviewed; both to decrease operating costs, increase productivity and to make the shopping experience more appealing. Energy use for lighting accounts for 50% of the total energy use in non-food retail stores, which is consumed primarily during daylight hours. Therefore, designing for daylighting and electric lighting integration is fundamental to obtain energy savings, as well as keeping occupants healthy and satisfied. This thesis describes field monitoring and supplementary building performance simulations of an existing daylighting and electric lighting integrated design for a furniture store. The store includes several areas of the showroom equipped with abundant daylighting. For the monitoring, the areas of the Living Room and Home Decoration exhibitions were selected. They include wide glazed areas, daylight harvesting systems, and tunable lighting. The monitoring procedure assesses four aspects: energy use, objective or measurable lighting conditions, circadian potential, and subjective evaluation of lighting. This study introduces an assessment based on the customers' path, which proved particularly informative in a retail setting. The results suggest that the integration project was successful in terms of energy saving, as well as customers and staff appreciation. Observations allowed a critical view on some of the objective photometric measures. Surprisingly, limited glare which simulations showed to occur, seems not to be a problem for users, rather an opportunity in a retail scenario. The customers were more attentive to daylighting and observing objects under natural light, and having a (good) view to the outside was the most positively evaluated. Clients also reported a better shopping experience compared to equivalent shops. Staff members showed satisfaction with the electric lighting solutions, such as LED panels with automatic tuning of correlated colour temperature. For future projects, the study argues that daylighting in furniture shops may be an asset. In addition, for the methodological part, the monitoring suggests that objective and subjective evaluations should be always combined for a full understanding of the integrated project.