As part of our SLD research-in-practice project, we are sharing case studies of inspiring existing projects and/or collaborations, each one of them touching at least one of the 4 main topics we are investigating. We are happy to present here the first case study: IKEA Kaarst.
With an unconventional design of a retail building, this case study shows the client’s high ambition to build a more sustainable store by integrating daylight and a daylight harvesting system coupled with electric lighting with the aim to reduce energy consumption and improve the overall store experience for both customers and co-workers. By coupling research, funded by the Swedish Energy Agency and in collaboration with Lund University, an extra step was taken, and post-occupancy evaluations were carried out, showing high satisfaction levels from customers and co-workers, and the potential to further reduce the energy used by the electric lighting system, leading to better optimizations of newly built stores.
We consider this case study inspiring as it sheds light on the importance of working interdisciplinary, coupling daylight and electric light in early stages, as well as the value of post-occupancy evaluations. Furthermore, we also hope this reference inspires more collaborations between industry and academy.
This case study includes strategies for Energy Efficiency and improving Health & Wellbeing.
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INTEGRATING DAYLIGHTING AND ELECTRIC LIGHTING IN THE RETAIL SECTOR
Lighting design in the retail sector has been mainly relying on electric light as a source of illumination leaving natural light a seldomly used source of light due to its unpredictability, limited access, and ever-changing qualities. Whilst electric light offers the opportunity to display products in a controlled environment, it is estimated that 50% of the energy used in non-food retail stores is in fact spent in lighting  , offering integrated lighting systems a great opportunity for a significant amount of energy savings through an improved lighting design. In addition to potential health and wellbeing benefits for both customers and employees.
With this in mind, the IKEA store in Kaarst, Germany, which opened in 2018, was an international pilot project that aimed to explore the concept of integrated lighting design, as a testbed for developing sustainable strategies for IKEA's future stores. The building was designed to include skylights, windows with automated blinds, daylight harvesting and tunable electric lighting. The aim of implementing this strategy was to enhance customers and co-workers experience in the store, improve their health and well-being, and reduce the energy use of the lighting system in the building.
The subjective evaluations showed that approximately 80% of the responses greatly valued
the introduction of daylighting, as the overall perception of the store improved in comparison to their experience in other stores of the same chain. Having a view out also contributed to a less stressful environment that customers highly valued. Among the positive remarks, observing objects under natural light, namely with high colour rendering, whilst having a connection to the outside seem to be the most important factor for customers. In addition, staff reported satisfaction with the installed electric light including the tunable white LED panels that automatically changed in color temperature. Furthermore, glare was not perceived as a problem despite that the computer simulations have shown some glare risk potential, on the contrary both customers and staff reported positive feedback regarding direct daylight, especially since it was suitable for such a store type .
Effect of tunable white lighting system with cool and warm correlated colour temperature (CCT).
In summary, integrating daylighting and electric lighting design in retail spaces can have many advantages in terms of improving energy efficiency, health and wellbeing. It provides a number of co-benefits such as enhancing the shopping experience and the working environment for the staff. This case study included both objective and subjective post-occupancy evaluations that highlighted these benefits, and showed concrete evidence for the advantage of integrating daylighting as a part of the lighting strategy in retail stores. The benefits of designing retail spaces that take both daylight and electric light into account are vast and should therefore be prioritized more often in the design process.
Read the full report of IKEA Kaarst case study inside the final report, starting on pge 42:
We would like to thank Ola Sundelin (Inter IKEA), Niko Gentile (Lund University), and Rafael Campamà Pizarro (PhD student at Lund University) for their contribution in this case study. This research study was carried out as part of a collaboration between Inter IKEA and Lund University through the Swedish Energy Agency funding for the IEA SHC Task 61 / EBC Annex 77.
The Post-Occupancy Evaluation was carried out by Rafael Campamà Pizarro as partial fulfillment for the Master’s Degree in Energy-efficient and Environmental Building Design, Lund University.
 Jamieson, M., 2014. A $3 Billion Opportunity: Energy Management in Retail Operations.
 EuroCommerce, 2018. Retail and Wholesale in times of change. A manifesto for the new European Commission
 Campamà Pizarro, R., & Gentile, N. (2019). A case study addressing the benefits of daylighting and electric lighting integration in the retail sector. IEA SHC International Conference on Solar Heating and Cooling for Buildings and Industry 2019. Santiago, Chile: International Solar Energy Society. http://proceedings.ises.org/?doi=swc.2019.38.02
 Campamà Pizarro, R., & Gentile, N. (2021). Daylighting integration is an asset for the retail sector. International Energy Agency, IEA SHC Task 61 Subtask D.