Temperature distributions of ground in the urban region of Poznan City

The measurements reveal that the daily ground temperature fluctuations are discernible at the depth of about x = 0.35 m during strong sun irradiation in summer and about x = 0.1 m during short and scarce periods in winter. The comparison of the ground temperature distributions e.g. at the depth of about x = 1.5 m indicates that the ground covered with grass is more suitable to be used as the heat or cold source for horizontal ground heat exchangers for heat pumps and for air conditioning systems. Because at the depth of x = 1.5 m, which is typical for horizontal ground heat exchangers, the minimum average temperature of the ground in winter is about 5 °C under grass and about 4 °C under bare ground, but the maximum average temperature of the ground in summer is about 16.3 °C under grass and about 20.6 °C under bare ground.