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So comparing for buildings in Palermo (climatic zone B), particularly for vertical walls and
roofs, the values requested by the "Technical Standards" of Gescal for the transmittance
with current regulatory parameters to get the economic incentives, the results are the
following (Tab.3):
Table 3: Comparison between the values of trasmittance according to Gescal and the current energy
legislation
Transmittance (W/m
2
K)
Vertical walls
Roofs
Gescal standards
1,29
0,97
Current legislation
0,41
0,32
Therefore, the transmittance values for both the walls and the roofs must be reduced by
about one third. This is a significant sign of the energy loss of this huge existing building
stock.
The thermal properties of the envelope of some industrialized buildings realized in
the ‘70s
In order to illustrate the interventions necessary to adapt the buildings realized with
industrial techniques in the '70s to current energy standards, required by standards and
laws, a detailed energy analysis was carried out on 776 flats built in the Sperone-
Romagnolo district of Palermo by the Ravenna Consortium of Production and Labour
Cooperatives with the coffrage-tunnel technique.
The energy performance assessment of the housing complex of the Sperone was
performed in two stages. Firstly, qualitative study, based on local climate, sun exposure
and orientation of the facades in order to identify the more exposed ones to radiation in
summer, was carried out.
The second phase of the study concerned, however, the identification of potential heat
loss due to the discontinuity points of the building envelope and the calculation of the
thermal insulation of vertical and horizontal enclosures. This phase was anticipated by
the collection of technical documentation and field analysis of construction-technical
factors (typology of the structure, materials and functional layers of the technical
elements of the envelope).
The Sperone district is located in the southern part of Palermo, near the sea, where the
mean temperature is in the range of 7.5 °C -11.5 °C in winter and 18 °C -21 °C in
summer with the maximum often exceeding 30 °C, out of the comfort zone. The resulting
increasing need for cooling of the interior spaces realized through high energy
consumption conditioning systems has often caused continuous electric power
interruptions.
These data needed a particular attention with the aim of energy saving, not only to
reduce heat dispersion in winter, but also and mostly to the reverse process, meaning
the maintenance of the thermal inertia in the hottest period.
As it concerns with the analysis of solar radiation, it was observed that the most
irradiated facades are those facing north-east and south-east. The peculiarity of the
project disposition of buildings in the Sperone district, due to designers, prof. eng. B.
Colajanni, prof. arch. S. Lenci (Cottone, Basiricò, Bertorotta, Vella, 2010), to give unity
and recognizability to the housing complex, led to the realization of buildings differently
exposed, non-aligned to the roads, but rotated between 30° and 60°. These buildings are
equal to each other, derived by the joining of four different types, resulting in buildings in
line characterized by short transverse facades of fixed length (12 m) and longitudinal
facades of different lengths (between 25 m and 100 m). As it is evident by the following
plan, some facades are exposed to north-east and south-west and some others to north-
west and south-east.
