Civil Engineering Reference
In-Depth Information
In a similar way, it is possible to calculate also the thermal losses for each other
subsystem; by adding thermal losses and electrical energy demand of the heating
system to the building energy need, the primary energy need of the building is founded.
4 Case Studies
Two examples of typical low-performance constructions widely spread in Italian
cities were analysed.
Nevertheless, the case studies are not exhaustive of the overall national building
stock; in fact, as it has been highlighted by TABULA Project,(Corrado et al.
2010
)
which gave an overview of existing typology in 24 European countries, the dif-
ferences among the climatic zone in Italy caused the diffusion of various building
typologies both for the features of the envelope and for shape. Furthermore, even
the U-values spread in the territory, without an exact correlation between building
age and insulation level. The main features that characterize the national building
stock are the large percentage of historical buildings, (61 % of construction built
before 1970), and the low renovation rate, so that the potential energy savings
achieved by efficient refurbishment measures could be very high.
4.1 Case Study A
Case study A represents an existing single house, located in a suburban area of the
city. The building has a regular rectangular plan (Fig.
1
), and it has a single
inhabited floor, characterized by a non-heated underroof above it. The load bearing
structure is made of brick masonry, 35 cm thick, and the envelope is built with
bricks without insulation.
The windows have a double glazing with air (U
window
= 2.947 W/(m
2
K)),
while the ground and the superior floor, characterized by a 30 cm thickness, are not
insulated (U
floor
= 1.500 W/(m
2
K)); hence, the energy demand is very high: the
building is characterized by the energy class G.
The heating plant is composed of an old traditional boiler with radiators and
low-insulation distribution pipes, while the control of water temperature depends
on the external climatic conditions; the consequence is that the global efficiency of
the heating system is very low.
4.2 Case Study B
Case study B is a dwelling located on the third floor of a block, border on a stair
case with an external wall (Fig.
2
) and with heated apartments on the other walls
