From August to December 2005 dena carried out a field-test on non-residential buildings with the main goal of gathering first practical experiements with the new calculation method of DIN V 18599 and corresponding regulation drafts for full implementation of the EPBD in 2006. 30 issuers and 42 buildings took part in the field-test. At the end of December, 38 issued certificates and the experiements of the issuers could be evaluated. The general conclusion can be summarized by stating that the new standard provides a holistic approach for the calculation of buildings energy performance. The high complexity and the new approach nevertheless caused some difficulties in the practical transposition and make an extension of the tested simplified methods for data acquisition desirable. Also the implementation of the calculation routines in software solutions was highly recommended by the participants.