Fenestration refurbishment of an educational building: Experimental and numerical evaluation of daylight, thermal and building energy performance

Although strict building energy codes are implemented periodically in many countries, buildings continually consume a momentous quota of total primary energy. Potentially, new buildings can satisfy current building energy codes, while existing buildings require refurbishment. Recently, the fenestration system of a 4-story educational building located in Cheonan, Republic of Korea (36.815 degrees N, 127.114 degrees E) has been refurbished from single glazed double-sliding window system with aluminum (Al) frame to double low-e glazed double-sliding window system with polyvinyl chloride (PVC) frame. The main objective of this study was to investigate the performance of the window system prior to and after refurbishment, using experimental and numerical tools. In particular, daylight environment of a demarcated space within the reference building was examined. Thermal behavior of glazing systems and window frames was scrutinized using infra-red (IR) thermography. The dynamic behavior of window system in relation to building energy performance was evaluated through EnergyPlus. Reference data of the building and nominal operational schedules were used as inputs for the building model, while inputs for the window system were based on optical and structural parameters of its data sets. Owing to thermal inertia, temperature of the single glazing was on average 0.7-1.9 degrees C higher than the double glazing. Considering linear radiant heat loss through Al and PVC frames, the former showed an avearge temperature of 5 degrees C higher than the latter. Although electrical lighting energy consumption increased, the overall annual building energy consumption of the renovated building reduced by 51.1 GJ (i.e. 4.3%).