This paper presents energy conservation by energy audit and use of energy efficient lamps. In order to conserve energy and reduce electricity charges, energy audit is done for lighting system used in educational buildings and domestic applications. After comparison of energy efficiency, illumination level and cost of different bulbs, LED (Light Emitting Diode) bulbs are suggested to conserve energy, enhance energy efficiency, and reduce electricity charges. In order to demonstrate the proposed approach, different case studies are considered for energy audit and conservation of energy for the sustainable future. Finally economic analysis of energy saving and investment on LED bulbs and payback period is determined.