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

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.Evaluating the lighting performance of a retrofitted project using Simulations and Field Measurements in an education building at Lund University. Assessments based on both methods verify a good post-retrofitting lighting performance. To achieve a good indoor lighting performance is always an interesting topic for both real estate owners and building occupants. It requires not only a healthy lighting environment, but also an energy-efficient lighting system. Considered that often lighting systems in existing buildings are not satisfactory, a surge of lighting retrofit projects represent a good chance to upgrade the building performance and energy efficiency of building assets. This calls for a standardized procedure that would be able to evaluate the lighting retrofits holistically and to easily implement at the same time. On one side, it helps the owners and occupants to know the benefits from the retrofits and keep on track of a post-retrofitting lighting condition, in another way such procedure will help to build a database of light retrofitting cases as a reference for future implementations. Following a well-designed assessing protocol, a set of lighting metrics were studied for a retrofitted project in an educational building through measurements and simulations and in the end the outputs proved the retrofits being a success. The selection of the studied lighting metrics was depending on aims to quantify the daylight appearance by testing the daylight factor, to examine the visual comfort by testing glare probability and luminance ratio, to check the electric lighting energy use and the visual comfort of the lighting system by simulating the LENI (Lighting Energy Numeric Indicator) and illuminance uniformity. A few building codes and voluntary environmental programmes were referred to for judgement of the lighting quality. The results complied with them, in general achieving a good visual comfort under both daylight and electric lighting condition. When comparing the evaluated metrics between measured and simulated values, it is satisfactory to see the deviation between each method is small. Such as, the room has a daylight factor of 2.44% from measurement versus 2.67% from simulation. The simulation-generated photos in the glare study reflected well the actual scene. It was found through simulations that the lighting system of an absence occupancy control system in the studied room helped to reduce approximately 18% of the energy use in replace of the lighting system with a manual on/off switch, even though that due to a low installed lighting density and short occupied hours, the annual lighting energy use was originally very low. The study also investigated the impacts of design parameters on the energy use of different lighting control systems. It was verified that a more complicated control strategy does not necessarily save more energy. In the end it is a pity that economic issues were not considered in the study which would affect the decision of lighting retrofit measures by its payback times