Policy Instruments: The Case of Germany - Nearly Zero Energy Building Refurbishment - page 19

Diefenbach et al. ( 2010 ) identified interesting results about the refurbishment
characteristics in the German building stock. Accordingly, the refurbishment rates
of different building shell components vary significantly. Thus, the building roof,
respectively topmost ceiling, is refurbished most frequently (ca. 1.5 %), followed
by the façade insulation (ca. 0.8 %) and ground floor, respectively basement
ceiling (ca. 0.3 %). No considerable difference between single- and multi-family
buildings has been identified.
Diefenbach et al. ( 2010 ) analysed that in about 20 % of the single- and two-family
buildings and approximately 26 % of the multi-family buildings, the façade has
subsequently been insulated. Almost 50 % of the roofs have subsequently been
insulated but just about 10 % of the ground floors, respectively basement ceilings. In
total, it is estimated that between 25 and 30 % of all building component areas have
subsequently been insulated after their construction. As some of the buildings
constructed before 1979 have already been insulated partly, Diefenbach et al. ( 2010 )
estimate that the share of insulated area in the building stock is about 10 % higher.
2 Definition of Nearly Zero-Energy Buildings in Germany
As the overarching topic of this topic relates to nearly zero-energy building
(nZEB) refurbishments, it is important to know how the standard of nZEB is
defined in Germany. As the German government has not yet finally published a
definition, this chapter aims to collect and describe all available information in
order to give a good overview of the current status.
'For a long time, Germany's development of energy performance requirements
for buildings has been accompanied by research and demonstration projects that
showed further strengthenings to be technically feasible, which became due to
market adaptations some years later also economically feasible. Figure 3 shows
the minimum energy performance requirements (in 6 steps) as the upper line, the
pilot projects (solar houses, low-energy buildings, three-litre houses, zero-heating
energy houses and plus energy houses) as the lower line and the actual building
practice in between. The requirements followed the pilot projects with 10 to
20 years time difference' (Erhorn-Kluttig et al. 2011 ).
'With the last tightening of the minimum energy performance requirements by
the energy decree, EnEV 2009 (Regierung der Bundesrepublik Deutschland 2009 ),
Germany has again become one of the countries in Europe with the strictest
requirements for new buildings' (Erhorn-Kluttig et al. 2011 ). But so far, the
German Federal Government has not yet defined a precise national definition for
nearly zero-energy buildings according to the EPBD. This fact can also be
explained as the EPBD requirements on the definition of nearly zero-energy
buildings are quite vague (Boermans et al. 2011b ) and have just been clarified
recently within the European Commission's (EC) research project 'Towards nearly
zero-energy buildings-Definition of common principles under the EPBD'
(Schimschar et al. 2013b ). However, already since years, the German government