This text provides updated coverage of key topics involved in integrated resource planning (IRP), also called least-cost planning. IRP in comparison with conventional power can provide the same energy services at a lower societal cost and with reduced environmental impacts. The history and basics of IRP is presented. The link between IRP and the environment is characterized in terms of impacts and cost-effectiveness. The book also features detailed chapters on IRP modelling, energy-efficient technologies, and international experience, including Eastern Europe and developing countries. The book is intended for researchers, specialists and electric utility staff involved in energy planning, electricity conservation, demand-side management and environmental planning.