This is a comprehensive book about Energy Efficiency, describing it as a solution to Low Carbon Economy. Energy efficiency has finally attained the status of a sensible term in everyday lexicon. These days, nearly everyone knows that using energy wisely is friendly on the pocket, lessens the emissions of greenhouse gases and lowers dependency on imported fossil fuels. We are part of a fossil age which is at the helm of its capability. Competition for securing resources for fuelling financial progress is rising, prices of fuels will continue to boost while their accessibility would gradually decline. Small countries will suffer the most and the earliest if they are not equipped to defend themselves in the midst of the fight for resources with the global superpowers. A well-versed man once rightly said "The only thing more harmful than fossil fuel is fossilized thinking". We believe that some of the information in this book will persuade readers to take a fresh look at the changeover to low carbon economy.