District heating and cooling (DHC) systems play an important role under the new European Union (EU) energy transition strategy. Thermal energy networks are helping to stimulate the development of alternative technologies based on a broad range of renewable energy sources. The present study analysed the current situation of DHC systems in Spain and provides an overview of the challenges and future opportunities that their use will entail. Its objective is to assess thermal energy conversion and management from a holistic perspective, including a study of existing energy infrastructures. The focus of this study lies on Spain given the country’s abundance of natural resources such as renewable energy sources including solar energy, biomass and geothermal energy, among others, as well as its strategic location on the map of the EU. Based on the analysis of the three factors for energy conversion in a district heating system, namely resources, technology, and management, the methodology provided an assessment of the different factors involved in running a DHC system. The results show an estimated total production for DHC networks of 1448 MWth, of which 72% is supplied purely by renewable energy sources.

Abstract.Energy efficiency is considered one of the most cost effective ways to enhance security of energy supply and reduce greenhouse gas emissions. According to Europe's Energy Efficiency Plan, the biggest energy saving potential in the EU lies in the built environment. Spanish authorities, aiming to guarantee the energy supply and also to abide with the environmental restrictions, have established the National Energy Efficiency Action Plans (NEEAP), the 2008-2012 Plan is the first one and the 2011-2020 Plan lends continuity.In this paper, we will analyze the measurements proposed by the 2008-2012 Plan for home thermal systems (heating and domestic hot water) and home electric systems (light and appliances). Three scenarios are established to quantify approximately the energy saving for Spanish dewellings in 2012. This paper evaluates, using data currently available, the saving to the year 2012 and compares it with the official Plan results presented. The results show the actual margins of improvement and the success or failure of the Plan measures.