Research of seasonal underground thermal storage in a net-zero carbon building

THE PURPOSE of this paper is to analyze the efficiency of a seasonal UTES for heating a residential building and optimize its operational modes based on experimental data from 2022-2024. Addressing the seasonality of this energy source will increase energy generation and achieve net-zero carbon for energy-efficient buildings. SIGNIFICANCE . For the first time, the actual operating modes of UTES in combination with flat-plate solar collectors have been experimentally assessed under conditions of a long cold period. The temperature limit for safe operation of the UTES with XPS thermal insulation (83.7°C) has been determined, which allows for increased design reliability. The data obtained has been used to adapt and refine mathematical models in TRNSYS, improving the accuracy of system operation prediction. Practical significance: achieving a reduction in energy consumption for heating and hot water supply of up to 42% compared to the baseline. Extension of the heating system operation period without turning on the heat pump – until December 20, 2024. Confirmation of the achievability of net-zero carbon for individual building. Potential application of the results in the design of energy-efficient buildings in cold climates. METHODS . Experimental measurements of equipment temperatures and energy consumption in 2022-2024. Mathematical modeling of thermal processes: ANSYS Steady State Thermal – determination of the maximum safe temperature of the heating system. TRNSYS – forecasting system performance in winter. RESULTS . The experimental and computational study enabled comprehensive analysis and evaluation of thermal energy production and consumption monitoring data The integrated heat pump and solar collector installation yielded substantial energy conservation: Electricity consumption for the heat supply system of building, thanks to the use of a heat pump and solar collectors, decreased from 4420 kWh in 2022 to 3050 kWh in 2023, i.e. by 31%, and in 2024 decreased to 2568 kWh, i.e. by 42%. CONCLUSION . The use of a UTES and solar collectors for the heat supply system, in combination with photovoltaic panels and electric car charging, ensured the achievement net-zero carbon in 2023 and 2024.