Energy conservation can be achieved through increased efficiency in energy and deceased use in total energy. Energy recovery also may be a part of energy conservation through captured and hence reduced waste energy. Energy conservation is an important part of controlling climate change by reducing greenhouse gas emissions. This chapter discusses the possibilities in conserving energy in power production, in compressor work, and in furnaces and boilers. This chapter also explores the energy conservation options in heating and cooling of houses as well as in lighting and driving. Some worked examples show that it is always possible to conserve energy by process improvements and by increasing efficiency of processes.