The statistical analysis of real estate data has received increasingly more attention during the last decade. Property owners, investors and banks are looking for cost-effective and reliable means to assess the value of single properties or even property portfolios. Additionally, building operating charges have turned out to be a major determinant of profitability of real estate investment, and the Europe-wide introduction of the energy certification for buildings in 2002 enhances the importance of accurate assessment of the energy efficiency of buildings even more. The main purpose of this...