The seminar describes in detail five energy efficiency experiences in Catalonia: an office building, a network of shops, a research complex, a seminar describes in detail the experiences of five energy efficiency in Catalonia: an office building, a network of shops, a research complex, a textile company and a company of rail transport. In each case, provide specific data on economic and environmental savings achieved as has been done. It also presents the book "Case studies of energy efficiency in Spain" with 35 examples of all sectors of economic activity.