The objectives of this research are to study the characteristics of the electrical power consumption of the air-conditioned and lighting systems and to analyse in order to find the approaches for energy saving as well as the economical engineering vakue of such systems that have been installed in the office of the Faculty of Industrial Technology and Gemological Sciences of Rambhai Barni Rajabhat University. The study was conducted on the subjects that consisted of a 36,000 BTU air-conditioning unit and16 T-8 type light bulbs. The size of the room, that was used for this research, was 8 square meters (m 2.). There was a two-tier test, one with the emphasis on the reduction of working hours whilst the other focused on the enhancement of the subjects efficiency (e.g. cleaning the air-conditioning system and replacing the light bulbs).