ZEMCH 2015 - International Conference Proceedings | Page 712

No condensation problems exist for the single-glazed aluminium windows, while there is an
enormous problem of dispersion externally. The transmittance value (u=5.531 w/m² k) is much
higher than the legal threshold of 0.2 w/m² k and the building in its present state is classified as
Class G (fig.5).
Therefore, the solution proposed to increase energy efficiency was, in the case of the simplex
apartments where no makeover of the walls was foreseen, to apply an 8 cm insulating cladding
over the exterior part and then a 2 cm plaster coating on the existing layer. Instead, in the case
of the duplexes, the choice was to replace the existing perimeter walls with 25 cm poroton masonry with an exterior 5 cm insulating coating and plaster. Both the new solutions resolve the
serious problem of thermal bridges which had occurred in the construction evaluation phase of
the buildings. In the case of the simplex apartments, it was verified, using the Glaser diagram, that
the altered walls would not have any condensation problems and the relative transmittance value
would be u=0.234<0.29 w/m² k. Similarly, for the duplex apartments, with the new exterior layer,
the transmittance would be below the regulation threshold of u=0.249<0.29 w/m² k.
As far as the windows are concerned, it was proposed to replace the existing aluminium

Figure 6: Building A new solution: new apartments and transmittance evaluation for external wall and
windows
frames with insulated 4-6-6 double-glazed windows with an exterior of Saint Gobain climaplus,
with the glass being coated in a low-emission film providing an even higher level of insulation,
and a hermetically sealed space filled with an insulating gas or demoisturizing air. For the horizontal closing cover it was proposed to apply, to the top surface of the damp-proofing layer, a layer of closed cell insulation which would decrease the transmittance value to u=0.238<0.26 w/m² k.
From the calculations, it was verified that with these simple modifications to reduce thermal dispersion, the building’s energy classification would increase to Class B (fig.6).
Instead, concerning domestic hot water production, often responsible for very high CO2 emissions, it was confirmed that, at the time of construction, the buildings were installed with a hot
water storage system with an electric boiler for each apartment, later replaced with an instant
heating hot water system with a gas boiler, which resulted in a marked increase in energy consumption and heating. The project’s aim was to reduce the CO2 emissions by foreseeing the installation of a centralized storage system, where the unused still hot water, would remain in the
boiler (accumulators) at a sufficiently high temperature, not requiring further heating. This type

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ZEMCH 2015 | International Conference | Bari - Lecce, Italy