The outputs of the used software tool SPSS show a highly significant single correlation (see Table 2) when comparing the thermal
consumption with the year of construction (x1) and the energy
standard (x2), which is based on the fact that there is a significant linear correlation between both of these predictors x1 and x2. In our case, this was the result of enacting the regulation [9]
described above. The very strong correlation between thermal consumption (y1) and the energy source (x6) could already be assumed
after analyzing the values in Fig. 2. All buildings with low energy
consumption figures were supplied with district heat in contrast to the inefficient buildings heated with fuel oil boilers