A stochastic thermo-economic analysis of thermal energy storage for residential cooling: The case of Spain

Electricity use in residential cooling systems has risen considerably in recent years, increasing their share in overall building energy demand and highlighting the need for advanced energy management strategies. Thermal energy storage offers a promising approach because of its operational flexibility and capacity to shift cooling loads to off-peak periods. This study presents a stochastic thermo-economic analysis of integrating cold-water storage tanks as sensible thermal energy storage in residential cooling systems across several climatic conditions in Spain. Three building typologies were assessed: single-family house, apartment mid-rise, and apartment high-rise, considering both air-source and ground-source air conditioning systems. Energy performance was simulated using TRNSYS software, and the results were used to conduct deterministic and stochastic economic assessments based on Monte Carlo simulations. Integrating thermal energy storage in air-source systems achieved electricity savings of up to 14.5% in Seville. In hotter climates, the percentage of energy savings remained nearly constant across building sizes, while in milder climates, smaller buildings showed greater savings. Incorporating thermal energy storage also reduced operational costs by up to 42.3% for the apartment high-rise in Seville owing to load shifting to cheaper electricity periods. Integration in ground-source systems was excluded, as no energy savings were observed. Stochastic analysis showed that the apartment high-rise exhibited better economic performance than the single-family house, with a 19.3% probability of positive net present value compared to 0.5%, while 90% of levelised cost of cold values ranged between 50.9 and 57.7 €/MWh. This underscores, the influence of electricity price dynamics on TES profitability.