Civil Engineering Reference
In-Depth Information
3.2 Defining a Performance Reference
In the Passivhaus-Datenbank (IG passivhaus Österreich n.d.), retrofit with Pas-
sivhaus components is defined as retrofit that results in a building with low-energy
demand. The heat demand is then B35 kWh/(m
2
.y). The Passivhaus Institute has
developed a specific standard for retrofit, EnerPHit (Passivhaus Institut
2010
),
limited today to residential buildings, in which the certification limit for heat
demand is B25 kWh/(m
2
.y). Alternatively, if this value is not met, a set of
requirements for the building components applies. In this latter case, the certifi-
cation will describe the building as ''EnerPHit—Quality-Approved Modernisation
with Passive House Components''. For the cases studied here, all the buildings
achieved a level of heat demand B15 kWh/(m
2
.y), as required for new buildings
by the Passivhaus standard according to the PHPP (Feist
2007
). In this article,
''Passivhaus'' refers to the original German standard, while ''passive house'' refers
to the general underlying concepts.
3.3 Case Studies
The research focuses on the achievement of four Austrian experiences, which
demonstrated the ability of the buildings to meet the criteria of the Passivhaus
standard through upgrading. Austria has shown to be in the forefront of Passivhaus
development (Lang
2009
). The result is a description of a common approach
allowing the Passivhaus level of energy efficiency and an analysis to identify sim-
ilarities and differences. The choice of the schools studied as empirical material was
determined and limited by the opportunity to visit those buildings during a single trip
and the relationships with relevant people developed during those visits allowing
access to key data. The four cases provide the foundation of the multiple-case study.
The case study is designed with the help of a protocol used as a guideline for
interviews and data collection and guaranteeing the reliability of the research design.
Interviews were held with key personal involved in the projects, and these were
guided by the protocol presented below. The Passivhaus-Datenbank is a good source
of basic information for all four projects. The Schwanenstadt project is further
described in several German reports (Lang et al.
2006
; Plöderl et al.
2008
), which
besides factual information about the construction, such as U-values and energy
consumption, feature analysis of the development of some critical elements of the
retrofit process. Reduction in thermal bridges, façade changes which include glazing
as part of the improved thermal envelope, and ventilation strategies are also
addressed there in more restricted units of analysis (Yin
2008
).
These cases can be qualified as exemplary as the concept is described by Yin
(
2008
). The exemplarity can be expressed at different levels: they are exemplary in
the context of building renovations in general, school retrofits in particular, and in
the achievement of the level of the Passivhaus standard in renovation. And because
