## 4 A Case Study of a Low-Energy House in Bialystok (NE Poland)  
According to the European Directive 2010/31/EU on the energy performance of buildings [128], a \"nearly zero energy building\" means a building that has a very high energy performance. The nearly zero or very low amount of energy required should be covered to a very significant extent by energy from renewable sources, including energy from renew \begin{table}
\begin{tabular}{c c} \hline \hline
**New Techniques and Emerging Trends** & **Sources** \\ \hline Support Vector Machine (SVM) & [110, 111, 112] \\ Multilayer Perceptron (MLP) & [113, 114] \\ Feed-Forward Neural Network (FFNN) & [115, 116, 117] \\ Back-Propagation Neural Network (BPNN) & [118, 119, 120] \\ Radial Basis Function Network (RBFN) & [121] \\ Multiple Linear Regression (MLR) & [122, 123] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: New Techniques and Emerging Trends towards Sustainability. able sources produced on-site or nearby. Member States have developed national plans for increasing the number of nearly zero-energy buildings. These plans include detailed requirements reflecting their national, regional, or local conditions. In Poland, \"nearly zero energy buildings\" [129] are buildings that meet the current requirements regarding energy saving and thermal insulation (WT2021, which entered into force on 31 December 2020), contained in the Regulation on the Technical Conditions that buildings and their location should meet [130]. It is worth emphasizing that, according to the report Zero-Emission Poland 2050 [131], these requirements are not sufficient to achieve the long-term energy and climate goals as defined in the EU's Long-Term Strategy [132]. Therefore, it is recommended, among others, to increase the current standards of thermal protection of buildings and require the installation of a photovoltaic system in new single-family buildings [131]. To present the possibility of erecting a building with low energy demand in the conditions of temperate continental climate (according to the Koppen-Geiger climatic classification [133]), the actual energy characteristics of a single-family house in Bialystok were determined. The geographic coordinates of the city are longitude 23.17\({}^{\circ}\) and latitude 53.1\({}^{\circ}\). The building in question consists of two heated floors. It is a building with a compact shape (Figure 6a), without a basement, and with an unheated garage on the north side. The facade with the largest glazing is oriented towards the south. The analyzed house is built on a polygonal plan, with an even number of sides, with right convex and concave angles; the difference between the number of convex and concave angles is 4 (see Figure 6b). The building plan view has a rectangular shape with the dimensions of 9.70 m \(\times\) 11.35/10.15 m. The building is covered with a shed roof with a wooden structure. Other basic geometric data of the house are:  
* total area: 171.89 m\({}^{2}\),
* volume: 822.3 m\({}^{3}\),
* usable heated area: 140.53 m\({}^{2}\),
* clear height of rooms: 2.70 m (ground floor) and 2.50 m (first floor),
* heated volume: 702.3 m\({}^{3}\),
* shape factor 0.70 m\({}^{-1}\). The building was designed in 2013, in accordance with the NF15 energy efficiency standard. NF15 is a term for the passive house, defined by the National Fund for Environmental Protection and Water Management in Poland (NFEP and WP) as part of a program supporting the energy-efficient buildings [134]. The building in this standard is characterized by the energy need for heating (Q\({}_{\rm H}\)) no higher than 15 kWh/(m\({}^{2}\) year). To achieve such a low energy demand, the building had to be:  
Figure 6: Photographs of the analyzed building: (**a**) south facade of the analyzed single-family building with an additional self-supporting light balcony system made of steel profiles; (**b**) layout of the analyzed building.