## 7 Very Shallow Geothermal Potentials of Ub  
Geothermal based heating (and cooling) solutions require certain favourable characteristics of the soil. Very shallow geothermal systems for instance require favourable petrophysical parameters realized in thermal heat conductivity of the soil. In order to explore thermal heat conductivity in Ub, the soil was analysed by _ThermoMap_ Viewer (Results presented in this part of the paper were obtained through _ThermoMap_ Viewer and its option vSGP Report. _ThermoMap_ Viewer is available at www.thermomap.eu). _ThermoMap_ was a project funded by European Commission with the aim of mapping the very Shallow Geothermal Potentials (vSGP) in Europe [3]. It shows that the territory of the urban area of Ub splits almost equally in soil with 1.07 W/(mK) thermal conductivity, and soil with 1.21 W/(mK) thermal conductivity (These values are calculated by using Kersten formulas [93]) (see Figure 5). One area in the eastern part of the urban area of Ub is located, and chosen as a potential test field (see Figure 6). This test field is used for the purposes of this article to present an estimated model and show how very shallow geothermal potentials in Ub could be activated. This test field has around 26,000 m\({}^{2}\). It is surrounded by around 90 households, and located on the edge of the urban settlement. Most of the houses on the potential network consist of one or two households. It would make the planning process and eventual connection to the network less complicated, because of less parties involved in a process. According to _ThermoMap_, a slope on the test field which is less than 15\({}^{\circ}\) is a favourable condition for very shallow geothermal system in a hydraulic point of view for e.g., horizontal collectors or special forms like heat baskets (see Figure 7). Figure 5: Very shallow geothermal potentials in the urban area of Ub (own map based on _ThermoMap_). _ThermoMap_ reveals also climatic conditions for the test field (see Table 1). Mean annual air temperature for the chosen site is 12.08 \({}^{\circ}\)C, while annual precipitation is 760 mm with maximal monthly precipitation in June. The nearest official meteorological station of the Serbian Hydrometeorological Service [95] shows similar results (see Table 1). Accordingly, climatic conditions of the selected area are favourable for utilization of vSGP--there are humid conditions. The following results from the _ThermoMap_ Viewer Report for the Test field in Ub also show no limitations for the utilization of the vSGP. Dominant soil type according to the World Reference Base is Luvisol (\"Luvisols have a higher clay content in the subsoil than in the topsoil, as a result of pedogenetic processes (especially clay migration) leading to an argic subsoil horizon. Luvisols have high-activity clays throughout the argic horizon and a high base saturation in the 50-100 cm depth\" [96] (p. 165)). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Location** & **Mean Ann. Temp.** & **Ann. Precipitation** \\ \hline Ub (Test field) 1  & 12.08 \({}^{\circ}\)C & 760 mm \\ Valjevo (Meteorological station) 2  & 11.40 \({}^{\circ}\)C & 788 mm \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Climatic conditions—Ub and Valjevo. Figure 6: Potential test field in Ub and its surrounding (own map based on _ThermoMap_). Figure 7: Horizontal collectors and heat baskets [94] (p. 240). This soil type should not have restrictions regarding the installation of (very) shallow geothermal systems. The dominant grain size distribution is medium according to the European Soil Data Centre (ESDAC) soil texture classification. Thermal heat conductivity is defined essentially by texture, water content and bulk density of the soil [37]. _ThermoMap_ predefines bulk density (relation between mass and volume) for selected area at 1.3 g/m\({}^{3}\). On the basis of humid conditions, a possible thermal conductivity value is 1.07 W/(mK).