The EU Directiv on the "Total efficiency of buildings" claims the introduction of mandatory energy performance certificates for buildings. The certificate needs to be made accessible in cases of new construction, purchase or rental of buildings and flats. According to the EU, the Directive had to be implemented within the member countries until 2006. In order to prepare the ground for the national implementation, the German Energy Agency (dena) conducted a field test for residential buildings between 2003 and 2004. The Fraunhofer ISI together with the Eco-Institute and the Fraunhofer Institute for Building Physics were assigned to evaluate the field test.

Objectives and methodical procedures

With the objective of gaining insight into optimization of the dena energy certificate prototype and the precepts of its compilation, the field test was also subjected to an accompanying evaluation. Focus of the study was market acceptance and market effects of the energy certificate, implementation aspects of issuing the energy certificate and balancing the calculation procedures.

A total of 3.925 energy certificates were taken into consideration in the evaluation process. By the conclusion of the project, 4.122 energy certificates had been issued. The database served as a basic address book for interviewing building proprietors, carried out in the form of in-depth telephone interviews, complete written data acquisition from all proprietors. Additional in-depth telephone interviews with the proprietors of buildings, representatives of joint ownership committees and tenants were conducted for in-depth treatment of specific questions.

Results

In summary, it can be noted that the energy certificate is considered as very sensible for private owners, in particular when they use their house themselves. The "message" of the energy certificate is clear: the idea of such verification of energetic quality is welcomed by most, and an effect on the housing market may also be expected. For this reason, the rating of the energy certificate should be kept firmly in hand. The key results of the evaluation can be summarized as follows:

• The costs of energy certificates have kept to a reasonable and accepted order of magnitude.
• Modernization recommendations in the short form are useful since they influence the decision-making process. 
• The flow of color on both versions of the label has been well received.
• A market effect of the energy certificate is to be expected if it is initially able to assert itself among own-property users.
• Following the broad introduction of energy certificates, the data contained therein represent a valuable database for energy statistics of private households in Germany. 

You can download an English version of the evaluation report here ( 235 KB) .