The book details the research commissioned by the Foundation from Dr. Castells and is based on applying the LCA methodology to energy consumption in Spanish homes. The study gives figures on the "ecological rucksack" carried by different uses of energy in the home, i.e. the total materials and energy used from the extraction of the raw materials to the final waste produced. This is the first study of this type applied to domestic energy consumption in Spain. The book was presented in Madrid on 2 July 2008.