Estimation of Energy Savings Due to the Integration of Daylight with Artificial Lighting in Classrooms

Nowadays, there is a growing awareness of energy consumption and its impact on the economy and global emission. There are many reasons that make energy conservation in buildings a critical issue throughout the world, such as limitation of energy recourses, the rapid increase in energy cost, environmental problems and saving energy for the next generations. Artificial lighting systems are a major consumer of electricity in buildings, particularly in educational and office buildings and beside that significantly contribute to building cooling load. Furthermore, artificial lighting does not necessarily provide the required quality of illumination. Daylight, if properly integrated with artificial lighting, can significantly reduce energy consumption and improve lighting quality. Integration of daylight with artificial lighting requires the use of proper lighting control system. This paper's main objective is to estimate the potential energy savings due to the integration of daylight with artificial lighting in classrooms in a tropical climate. The impact of different window design parameters, including window area, and glazing type, on lighting and energy consumption, is investigated through a parametric analysis. Energy Plus software is used for this analysis because of its availability, validity and accuracy. Results show that there is a great potential to reduce total energy consumption and substantial energy savings in electricity consumed artificial lighting systems can be obtained when daylight and artificial lighting are properly integrated. In Particular, results revealed that lighting energy consumption can be reduced by 28% to 40% and 10% to 18% in total energy consumption. It is recommended to consider the efficient integration of daylight with electric lighting by proper window design and using proper lighting control system at early design stage because this can significantly contribute to reducing energy consumption in schools.