Daylight Factor for Energy Saving in Retrofitting Institutional Building

In Malaysia, lighting is the second electric power consumption after air conditioning and it is increasing every year. Most of the lighting design standard for building in Malaysia is based on MS1525, and this being taken without further measure on daylight consideration. Movement from inefficient and unsustainable energy practice to more energy efficient initiatives is vital for building. Universiti Teknologi Malaysia as one of the major institutional building is consuming 9 to 16 million kWh per year. Thus, about 20% of energy consumed was from artificial lighting. This paper aim to highlights the cost benefit study of lighting retrofit, which integrates the utilization of daylight into existing building. Data for this study was obtained through illumination in-situ measurement on two types of artificial lighting with the inclusive of day lighting before and after lighting retrofit. The measurement was conducted in a typical building in Block C09 of Universiti Teknologi Malaysia (UTM). Annual saving and payback period were analysed from the collected data. It is estimated that total energy consumption decreasing around 47.7% over a year from 84,232kWh to 44,014kWh by retrofitted the fluorescent T8, 36W with fluorescent T5, 25W. The estimated total annual electricity bill saving is at RM11,073 (USD3500.00). The return in retrofitting cost is at 2.5 years payback period. The payback analysis portray that lighting design is best integrated with daylight. The significant amount of saving in energy consumption and the cost of retrofit is obtained by integrating daylight as a source of lighting for interior space.