Introduction
Indoor swimming pool facilities are classified among the most energy-intensive public buildings due to their continuous operation and the high demand for thermal energy, electricity, and water. The necessity to maintain stable thermal and hydraulic conditions for sanitary safety and user comfort results in substantial energy consumption, primarily associated with pool water heating and mechanical ventilation systems. The temperature of the pool water directly governs evaporation intensity, which affects latent heat losses, indoor air humidity, and ventilation loads, thus creating strong interdependencies between the water treatment processes and energy demand. The consumption in swimming pool facilities is mainly driven by filter cleaning, water renewal requirements, and sanitary regulations, which further increase the demand for thermal energy due to the need for continuous reheating of make-up water. As a result, the heating, ventilation, and pool water treatment systems form an integrated energy–water system, in which suboptimal installation design leads to increased energy consumption and operational inefficiencies. Rising energy prices, growing pressure on freshwater resources, and the implementation of climate and environmental policies require the improvement of energy efficiency in existing swimming pool infrastructure. Many facilities constructed 15–25 years ago lack integrated solutions for energy management, heat recovery, and water reuse. This study addresses this gap by evaluating the role of installation design in improving energy and resource efficiency, with a focus on integrated modernization strategies based on hybrid energy systems and water recovery technologies.
Methods
The study used a case study methodology applied to existing indoor swimming pool facilities located in different climatic regions of Poland: Ełk, Limanowa, and Skoczów. The selected facilities represent different construction periods, system layouts and operational profiles, allowing a comparative assessment of energy and water performance under varied boundary conditions. The first stage involved the determination of the baseline energy and water consumption. This assessment was based on long-term utility billing data, measurements from building management systems (BMSs), direct meter readings, and supplementary on-site measurements. The collected data was used to quantify annual and specific consumption of thermal energy, electricity, and water, as well as to identify the dominant energy loads associated with pool water heating, air handling units, ventilation, and auxiliary installations. Subsequently, a detailed technical evaluation of heating systems, ventilation, air conditioning (HVAC) units and pool water treatment installations was performed. Based on functional and energy analysis, multiple retrofit scenarios were developed and modelled, including gas-fired boilers, electrically driven heat pumps, micro-cogeneration (CHP) units, photovoltaic (PV) systems, and hybrid system configurations. For each scenario, steady-state energy balances, operational expenditures, and CO₂ emissions were calculated, accounting for regional climatic conditions, energy price structures, and system efficiencies. Energy analyses were further integrated with assessments of water recovery potential, water reuse schemes, and heat recovery from wastewater streams, enabling a comprehensive evaluation of coupled energy–water optimization strategies.
Results
The results indicate that optimized installation design and system configuration, particularly the integration of multiple heat and power sources, significantly enhance the overall energy performance of indoor swimming pool facilities. The analysed facilities exhibited annual thermal energy demands in the range of 1.25–1.64 GWh year⁻¹ and annual electricity consumption between 0.82 and 0.89 GWh year⁻¹ under baseline operating conditions. These values confirm the high energy intensity characteristic of indoor swimming pool infrastructure. The implementation of hybrid energy systems that combine microcogeneration (CHP) units, electrically driven heat pumps, and photovoltaic (PV) installations resulted in substantial reductions in energy demand. Thermal energy consumption decreased by 20–50%, while electricity demand was reduced by 15–25%, depending on facility size, operational profile, and system configuration. Renewable and hybrid energy systems were capable of covering approximately 40–70% of the total energy demand, thus significantly improving energy autonomy. These improvements translated into operational cost reductions of up to 50% and an annual decrease in CO₂ emissions of approximately 30–40 t CO₂ per facility. The highest energy performance was observed in facilities equipped with integrated control strategies that coordinate pool, heating, ventilation, and irrigation systems, which enabled load balance, reduced peak demand, and improved overall system efficiency.
Conclusions
The study confirms that installation design has a decisive influence on the energy performance of indoor swimming pool facilities. Modernization strategies should therefore address the facility as an integrated energy–water system throughout its life cycle. Combining renewable energy technologies with water and heat recovery solutions enables substantial reductions in energy and water consumption while maintaining user comfort and sanitary safety. Such an integrated approach supports the transition toward low-emission, resource-efficient swimming pool infrastructure consistent with circular economy principles.
