Civil Engineering Reference
In-Depth Information
In addition to the four cases presented here, the Passivhaus-Datenbank shows
(as of November 2010) a non-exhaustive list of 8 additional projects for retrofits
with PH components: Ainet, Neumarkt, Wolfurt, Velden, Bezau, Alberschwende,
Hörbranz and Mäder. Their performances, as calculated with PHPP, show heat
demands between 7 and 27 kWh/(m
2
.y), and heat loads between 10 and 27 W/m
2
.
Some projects mention air tightness values between 0.3 and 0.6 1/h. Primary
energy was not requested for the first version of the database and the information is
missing for most projects. However, considering the spreading of Passivhaus
renovation for residential buildings, it is reasonable to suppose a similarity for
school buildings and that the results described in this study can be achieved in
most school renovations.
Nevertheless, a lack of clarity can arise as to whether the Passivhaus fulfilment
is real or approximate, or whether it actually meets the exact requirements of the
Passivhaus standard. This is because the studied buildings are not certified to the
Passivhaus standard and some alternative methods are used to calculate some
values. Methods of energy calculations in buildings are described by standards like
ISO, but in our case, the national Austrian norm was used, which delivered a
specific energy certification (OIB-Energiausweis). Generally, numbers for heat
demand obtained from this official calculation (as with, for example, Sonderschule
4) differ from numbers calculated with PHPP. These differences can be conse-
quential, with the OIB number being 20-50 % lower than the PHPP number—as
the examples from the Passivhaus-Datenbank show—and this fact is confirmed by
Austrian expertise (personal communication, Günter Lang, November 2010).
Nevertheless, Passivhaus concepts were fully applied in the cases presented.
6 Conclusion
The four cases of this research, all large buildings from the 1960s and 1970s, show
a remarkable exemplarity with reductions in heat demand better than 80 %. In
particular, Schwanenstadt shows a striking 82.4 % improvement compared to the
original traditionally planned refurbishment. The results of the case study provide
a strong paradigm for a radical upgrade of energy efficiency. Within this paradigm,
these school retrofits addressed important design issues and provided appropriate
solutions for a strong control of thermal performances such as continuous external
insulation solving thermal bridges on the façades. Both prefabricated elements and
on site construction were used. Both these approaches allowed to also secure air
tightness. In addition, mechanical ventilation with highly efficient heat recovery
has been installed in all the buildings allowing good IAQ and highly improved
comfort. Two approaches are equally valid: central systems or room units. The
buildings have not been certified as Passivhaus; therefore, the judgment of the
quality of the buildings as Passivhaus is only based on the control of air tightness,
the design calculations with PHPP (and the trust that these calculations are true),
and that the buildings are built according to the calculated design. Nevertheless,
