Evaluation of a light shelf based on energy consumption for lighting and air conditioning

The shading effects of light shelves in indoor thermal environments have not been investigated to date. Thus, this study aims to identify the effectiveness and appropriate parameters required for a light shelf by evaluating its performance in the presence of lighting and air conditioning. A full-scale testbed was established in this study for evaluating the performance of the light shelf. Moreover, the performance evaluation was conducted by calculating the energy consumed for lighting and air conditioning to maintain proper temperature and illuminance. This study found the following: (1) During summer, the use of a light shelf would reduce the energy consumption for lighting and air conditioning by 0%–10.5% and 6.9%–9.3%, respectively. (2) During winter, the use of a light shelf would increase the energy consumption for lighting and air conditioning by 0%–25.3% and 0.2%–3.2%, respectively, which is undesirable. (3) Increasing the angle of the light shelf would increase the amount of light penetrating to indoors, thus would reduce the energy required for lighting. Based on these findings, we recommend the installation of a detachable light shelf that is 0.6-m wide with a 30° angle for buildings in Korea; and during winter, the light shelf should be removed to save energy