Book excerpt: Efficient Use and Conservation of Energy is a component of Encyclopedia of Energy Sciences, Engineering and Technology Resources in the global Encyclopedia of Life Support Systems (EOLSS), which is an integrated compendium of twenty Encyclopedias. The Theme on Efficient Use and Conservation Of Energy discusses matters of great relevance to our world such as: Efficient Use and Conservation of Energy in the Industrial Sector; Efficient Use and Conservation of Energy in Buildings; Efficient Use and Conservation of Energy in the Transportation Sector; Efficient Use and Conservation of Energy in the Agricultural Sector; Using Demand-Side Management to Select Energy Efficient Technologies and Programs . These two volumes are aimed at the following five major target audiences: University and College students Educators, Professional practitioners, Research personnel and Policy analysts, managers, and decision makers and NGOs.