*3.3. Characteristics of Zone C*

In zone C (Figure 1), 68% of the buildings were insulated, as they were mostly relatively new buildings built on the outskirts of the city. The closer to the centre, the more the number of insulated buildings decreased and their age increased. Most of the insulated buildings were observed to be in breach of the building code (Ordinance concerning the technical conditions to be met by buildings and their placement of 2014), specifying the maximum energy intensity parameter at 120 kWh/(m2annum). This situation was similar to the one observed in zone B [58]. The thickness of buildings insulation layers varied between 5 and 10 cm (Figure 12). In zone C, 35% of buildings were heated with coal, which significantly contributed to the deterioration of the quality of the environment in this area, similarly affecting zone A, located at the valley floor. According to the Municipal Office, the average age of coal-powered boilers in Radzionków was 17 years—it can be assumed that the average age of boilers in this area was slightly lower than listed in statistical data. Most of the buildings in this zone are dated to the post-war period and were erected between 1960 and 2010.
