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The energy consumption for space heating and domestic hot water preparation are significant burdens of a polish household budget, especially in old tenement houses. Simultaneously, lowering the emission of pollutants is under the great importance and one of main goals to achieve in big cities. This policy results in the need of elimination of systems based on solid fuels. The article analyses the environmental and social consequences of the exchange of heat sources in such buildings in one of the quarters in Wroclaw. It presents how this change will affect the levels of low emission and costs of energy supply to tenement buildings.

The negative impact of systems based on fossil fuel on the environment and the desire to promote sustainable development is increasingly encouraging building owners to invest in renewable energy sources. One of the possibilities of using a renewable energy source located in shallow soil layers is a brine-to-water heat pump. Ground energy can be used for both heating and cooling buildings. This article presents the advantages of balancing the supply and energy consumption from the ground for the large heat pump systems. Authors presented a case study and the simulation of the system operation with different cooling load share vs heating load. This was done on the basis of the analysis of data from several years of measurements from the actual installation as well as the simulation in Earth Energy Designer software. The results of the simulations shows that the most advantageous strategy for the operation of the analysed installation is to provide 50 to 75% of the cooling load in relation to the heating load.

Paper shows the performance analysis of the boreholes being the lower heat source for the brine-to-water heat pump. Researchers focused on the changes of the specific power extraction rate change in time and in various loads. The measurements were the continuation of the analysis of the differences between the Thermal Response Test (TRT) and exploitation data made in 2016/2017 heating season. The heat source performance under greater load and in longer period have been examined. The analysis showed brine temperature drop in overload work conditions even when ambient temperature was high and severe heat source destabilization despite a return to original performance.

In the paper the analysis of the operation of ground-source heat pump with various heat-carrier fluids circulating in boreholes was made. The authors considered several aspects related to the heat-carrier fluid selection (freezing point, heat transfer capabilities, toxicity, pumping costs). The lower heat source analysis had been performed in Earth Energy Designer (EED) software. The analyses’ results reliability was assured by the ground-source model calibration made basing on the measurement data from on-site test stand. Analyses were performed for four heat-carrier fluids (two kinds of propylene glycol solutions – standard and with lower viscosity, water and nanofluid (water + CuO)) and in four variants of thermal load (design and actual loads both with and without active regeneration). It had been concluded that temperature of none of the fluids would drop under 0°C if the system was operated under actual thermal load. For design thermal load there would be a risk of the water freezing but it may be minimized by active regeneration or lower heat source enlargement by 20% (in analyzed case) each rising the mean fluid temperature by around 1.0-1.5 K. The use of other fluid in place of standard propylene glycol solution will give pumping energy savings.

In the paper the simulations of the low enthalpy energy source for brine-to-water heat pump using EED software had been presented. Authors indicated the influence of the ground parameters’ assumptions on the low enthalpy heat pump’s energy source simulation’s results. Based on the real borehole geological profile and data available in literature, the ground thermal conductivity coefficients have been calculated making different assumptions concerning the ground thermal properties. The calculated ground thermal conductivity coefficients along with the calculated source sizes, heat pump parameters and the heated building thermal performance served as the input data for the simulation software. The outcomes of the analyses include the temperatures of brine entering the heat pump as well as the brine initial temperature. Outcomes served for the low enthalpy energy source performance evaluation.

The article discusses the principles and the problems of obtaining an accurate data input for the design of brine-to-water heat pump’s vertical exchangers. Currently, the most accurate method is the thermal response test (TRT). Unfortunately, the test procedure has its limitations and the quality of the results depends on many factors that cannot be fully controlled during the test. As an illustration of the problems, the results of the TRT were presented. The test was executed on the vertical boreholes (one actively regenerated and one not actively regenerated during the summer) which are parts of the operating heat pump system. The test results were compared to the data from the device’s operation, in particular with the measurements of the undisturbed ground temperature profiles and the actual unit energy gains from the boreholes. The level of difference between the results of the test and the data from the operation of the boreholes under the real load and the threats concerning the boreholes overload were shown. Additionally the performance differences between the actively regenerated and not actively regenerated boreholes have been emphasised.