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of the building mass (Itard et al.
2008
, pp. 32-33); therefore, existing buildings
provide the main potential for energy savings and require a strong focus.
Any need for retrofit, repair or maintenance to the envelope of a building is a
good opportunity to undertake an upgrade in energy efficiency. Several studies
(Plöderl et al.
2008
; Dokka and Klinski
2010
; Bretzke
2009
) indicate that a radical
energy retrofit can subsequently even pay for itself due to the important energy
savings. Several levels of retrofits can be identified. Very limited actions may not
interfere with the energy efficiency, but in general, most actions—even minor
actions—have an impact on the overall energy efficiency of a building, or may
impair the ability to improve this efficiency at a later date (Bodem
2010
; Feist et al.
2009
). Consequently, a radical approach to energy efficiency improvement is
needed to get the best return on investments.
The case of small residential buildings retrofits seems well covered (Feist et al.
2001
; Schnieders and Hermelink
2006
; Pedersen and Peuhkuri
2009
; Herkel and
Kagerer
2010
; IBGE
2009
; Beedel et al.
2007
). Larger non-residential buildings
are, however, subject to increased interest (Itard et al.
2008
; Thomsen and Witt-
chen
2008
; Waide
2006
; Herkel and Kagerer
2010
). Among these, school build-
ings are an interesting group (Kluttig et al.
2002
; IEA
1991
; Butala and Novak
1999
). Due to the many challenging conditions during extensive energy upgrade,
they deserve special attention. Meeting the requirements in such buildings may
provide important knowledge in upgrading towards highly energy-efficient
buildings on a broader scale. Austria is a European country providing extensive
models and practical examples on how such radical energy retrofits can be
attained. Notably, several school buildings have been retrofitted achieving between
80 and 90 % reductions in heat demand. Such reductions actually go far beyond
the levels of most of other international references (Kluttig et al.
2002
; Butala and
Novak
1999
), while knowledge about these retrofit projects has had only limited
attention in international scientific publications. A systematic, in-depth knowledge
is largely lacking. The main aim of our study was to make such knowledge public
to an international scientific audience.
Four Austrian school buildings, that could be visited and studied in situ in 2010,
were selected for a multiple-case study. They all represent implementations of the
Passivhaus standard (Lang
2009
); an approach with clear principles, and a vali-
dation scheme that allow radical improvements of energy efficiency of buildings at
the expected level of nearly zero energy. Such a system also provides a solid
foundation for coherent case studies, analyses and comparisons.
First developed in 1994 as a standard for residential buildings by the Passivhaus
Institute (PHI
http://www.passiv.de
), the Passivhaus standard has won wide
international recognition and application in a variety of climates. The standard is
linked to the ''passive house planning package'' (PHPP), a tool that allows vali-
dation of the design (Feist
2007
). This standard is now used for all kinds of
building and also as a reference for retrofits.
Retrofits represent larger challenges. The PHI has recently (
2010
) introduced a
set of requirements for the certification of retrofits of existing buildings called
EnerPHit.
The
substantial
number
of
constructions
designed
or
retrofitted
