Technical-economic and environmental analysis of DHW systems in Spanish climate zones

Abstract

There are many systems on the market for domestic hot water (DHW) production. Spanish legislation requires that 60% of the energy needed to produce DHW be of renewable origin. This work analyses the economic, energy and environmental viability of seven DHW production systems installed in six climatic zones of Spain. The systems combine the equipment: gas boiler, solar collectors, heat pump, photovoltaic and electric heater. The calculation tool used for the simulations has been EnergyPlus. Results show that the system that combines solar collectors with gas boiler is the one with the lowest energy consumption and the lowest amount of emissions in all climatic zones, although in areas with intermediate and cold climates, heat pump with photovoltaic system has a similar consumption and emission level. The system with the highest consumption and emissions is the electric boiler. The total life cost analysis includes the capital cost, the annual maintenance and the energy consumption for a 15-year period. In contrast to energy results, the most economical system for the life cycle is the gas boiler for all climatic zones, due to its low capital and maintenance cost. The heat pump system is the best economic alternative to reduce energy consumption and CO2 equivalent emissions.