Assessment of Daylighting and Electric Lighting Performance in a Retrofitting Project: A Case Study in Sweden

Sammanfattning: Newly constructed building stocks have been decreasing in last decades; thus, renovation and retrofitting represent a large amount of opportunities to upgrade the building performance and energy efficiency of building assets in their life span, as well as to reduce greenhouse gas emissions. An overall assessment of a lighting retrofit project can support to judge the quality of a retrofit as good or bad and evaluate the application of a retrofit measure in practice, as well as provide quantitatively based cases for future implementations. In this thesis, a lighting assessment was conducted for a retrofitted project in an educational building situated at Lund University, Sweden. The aspects with regard to both daylighting and electric lighting performance were studied through field measurements and simulations. The main objective is to evaluate lighting performance of the case room, as well as to investigate the deviation between measured and simulated results according to data collected in daylighting assessment. The results demonstrate that the case room in general provides a good visual comfort space under both daylight and electric lighting condition. A few building codes and voluntary environmental programmes were referred to for judgement of the lighting quality, such as Miljöbyggnad (the Swedish green building certificate) and SS-EN 12464: 2011. The room has a daylight factor of 2.44% from measurement versus 2.67% from simulation. Glare probability is measured/simulated and results from both methods output a small value. Moreover, a deviation study of measured/simulated results was conducted and the results show a good consistency in general. Due to a low installed lighting density of 5.38 W/m2 and short occupied hours, the annual lighting energy use is very low. The lighting system in the case room has an absence occupancy control system with a sensor delay time of 15 minutes. It can help reduce approximately 18% of the energy use if compared to the lighting system with a manual on/off switch control based on computational results. The study also investigated the impacts of design parameters on the energy use of different lighting control systems and the results were discussed.