Civil Engineering Reference
In-Depth Information
5.1 Compactness
The compactness of a building expresses the relationship between the surface of
the envelope, through which thermal losses happen, and the volume to be heated.
A ratio is then calculated as area/volume, or envelope area/heated area. Energy
efficiency depends on reduced heat losses for a given volume to be heated, and as a
consequence is helped by a low compactness ratio. The compactness of the
building of the schools was retained or increased. Sonderschule 6, as a cube (see
Fig.
4
), is the most compact building. The other three buildings are elongated and
have the common feature of the second floor being extended as an overhang
covering the entrance, and are still very compact.
5.2 Concrete Structure
Three of the schools were extended; the extensions consisted primarily of the
addition of a full storey for both Sonderschule, and an additional storey was also
part of the extension for Schwanenstadt. The original buildings and their concrete
structures were not designed to accommodate additional stories. To cope with this
circumstance at both Sonderschule, light timber frame constructions were used to
allow the construction of an additional storey without extensive reconstruction of
the weight-bearing structure. Sonderschule 4's additional wooden columns carry
the new second floor. They are built on the outside of the old building, but inside
the thermal envelope. Further analysis follows the protocol described earlier in
Fig.
1
.
5.3 Building Envelope
5.3.1 Façade
Schwanenstadt and Zams-Schönwies originally had external and/or exposed
concrete columns on the façades with associated thermal bridges. For Sonde-
rschule 4, the columns were exposed at the window level. In all cases, those
columns are now incorporated into the building volume, so new façade elements
were placed on the outside of the former columns. The internal volume of the
building has increased by the thickness of the original concrete structure (for
Schwanenstadt, 50 cm of added space on the perimeter).
Windows are of passive house quality with a mean installed U-value of 0.8
W/(m
2
.K).
