Fig.5 shows the correlation between the consumption and the gross heated floor area. Being quite small preschools and primary schools, most of the buildings analyzed had less than 10,000 m2. The school buildings with a heated floor area of more than 10,000 m2 were all secondary schools. Surprisingly, there is not a significant linear correlation between the heat consumption and the building size for the analyzed sample. A significant decreasing correlation was expected as it is typical for very large buildings to have a lower A/V ratio compared to small primary schools with only a few 100 m2 of heated area. This, however, could not be confirmed and, as a result of this, other construction characteristics are more important than A/V ratio.