Abstract: This study presents the development of an experimental heat pump prototype based on the elastocaloric effect—a promising solid-state cooling mechanism that leverages the reversible thermal response of Shape Memory Alloys (SMAs) under mechanical loading and unloading. Unlike conventional vapor-compression systems, elastocaloric cooling offers a potentially more energy-efficient and environmentally friendly alternative, as it eliminates the need for refrigerants with high Global Warming Potential. The research is part of the project SUSSTAINEBLE (a Solution Using Solid-STate cooling: An INvestment Eco-compatiBLE) funded by the Ministry of University and Research (MUR) of Italy. The aim of this research, carried out by the group of the University of Naples Federico II, is the developing of a demonstrative prototype of the first Italian elastocaloric device for air conditioning. Air is the auxiliary fluid that will be used to avoid an intermediate heat exchanger. The operation of the device based on the AeR cycle uses a rotary mechanism that ensures a continuous flow of hot and cold air. A 2D rotative numerical model has been developed through COMSOL to attain the device's potential cooling and heating capacities and to optimize the geometrical parameters and the operative conditions of the device. The experimental setup utilizes nickel-titanium (NiTi) alloy elements, selected for their significant latent heat and mechanical resilience. The results of numerical simulations carried out following the optimization of the geometric parameters of the device are presented to analyze its potential in terms of energy performance. This work contributes to the growing body of research on solid-state cooling technologies and provides insights into the engineering and operational considerations necessary for scaling elastocaloric systems toward commercial viability.