Role of Thermal Storage in Distributed Air-Conditioning Plants: Energy and Environmental Analysis

Energy efficiency is becoming a crucial target in the construction of a decarbonized society to guarantee sustainable development and tackle climate change issues. The building sector is one of the major players being responsible for a huge amount of primary energy, mostly related to heating and cooling services. Aside from intervening on the building envelope, intending to reduce energy demand, it is of fundamental importance to consider appropriate air-conditioning systems that can easily integrate renewable sources and rationalize energy use. Heat pumps are an appealing solution because of the renewable energy available in the external sources and because of the possibility to drive them with PV systems. Solar assisted heat pumps have therefore become a promising solution for energy efficiency in buildings, allowing lower primary energy demands and generating lower CO2 emissions. The ulterior integration of thermal storage in the systems allows for a further improvement of energy efficiency. This paper investigates the achievable energy savings after interventions of energy efficiency on a building aggregate composed of four buildings. In particular, two different scenarios of improvement of the HVAC system substituting the existing plant with PV-assisted heat pumps are considered. The performances obtained with the use of single-heat pumps and a centralized one with thermal storage are investigated employing dynamic simulations conducted in the TRNSYS environment.