Economical comparison among technical solutions for thermal energy production in buildings based on both conventional and solar res systems

Greenhouse gas emission reduction and the control of excessive use of fossil fuels currently represent one of the main challenges of European energy policy and global Agreements, especially in order to limit dangerous climate changes. Particularly in EU such objectives are pursued through a wide range of regulation and incentive measures: strongly recommended are marked reductions in primary energy consumption and increase in the share of renewable energy. In developed countries a significant portion of primary energy is consumed in buildings: with reference to Italy, potential savings obtainable from the sector are about 40% of the national energy needs in end-use and 36% of GHG, that could be significantly reduced through sustainable design, energy efficiency increases and wider RES use. The study presents an energetic and economic comparison between the satisfaction of thermal consumption for heating, domestic hot water and washing water in household appliances in residential buildings, through technologies based on both conventional and renewable energy sources exploiting solar energy. Several configurations of both conventional thermal energy production systems (water heater, boiler) and thermal and electric renewable ones (solar collector, heat pump, photovoltaic system) have been considered, for which a comparison in terms of primary energy, avoided emissions and Net Present Cost has been made, estimating the respective convenience in their life span and identifying the cost optimal solution that guarantees user needs with lower investment and operating costs.