E n e r g y S a v i n g s i n B u i l d i n g R e s t o r a t i o n
137
the same of the monthly method described in ISO 13790 standard (EN ISO 13790,
2008). The Italian standard includes a lots of thermo physical data of several building
materials used in Italy. The part 1 of the Italian standard shows the method in order to
calculate the energy need for heating and cooling with mainly reference to the
characteristics of building envelope, while the part 2 describes the method in order to
assess the energy use for space heating and domestic hot water.
The main geometric characteristics of building are reported in Table 1.
Table 1: Main geometric characteristics of “La Masa” school building.
Floor
Gross
conditioned
area
(m
2
)
Gross
conditioned
Volume
(m
3
)
Useful
conditioned
area
(m
2
)
Useful
conditioned
Volume
(m
3
)
Area of
external wall
(m
2
)
First
847.89
4281.84
720.89
3496.32
808.51
Second
847.89
4281.84
658.29
3192.71
798.91
Third
847.89
4281.84
658.29
3192.71
798.91
Fourth
241.98
1222.00
133.29
646.46
477.03
Fifth
17.40
56.55
6.83
20.82
79.56
Overall
2803.05
14124.08
2177.59
10549.00
2962.91
The thermal transmittance of opaque and glazed building elements were calculated by
means of methods reported in EN ISO 6946 standard (EN ISO 6946, 2007) (e.g. see
Table 2) and in EN ISO 10077-1 standard (EN ISO 10077-1, 2006) respectively.
The heat loss by thermal bridges was calculated taking into account the method
described by EN ISO 14683 standard (EN ISO 14683, 2007).
Table 2: Calculation of thermal transmittance of one type of external wall (thickness 60 cm).
N.
layer
Description
Thickne
ss
s
(m)
Thermal
conductivity
(W m
-1
K
-1
)
Thermal
resistance
R
(m
2
K W
-1
)
1 Internal thermal surface resistance
0.13
2 Internal plaster
0.02
0.7
0.03
3 Cement mortar
0.05
1.4
0.04
4 Tufa stone
0.45
0.63
0.71
5 Cement mortar
0.05
1.4
0.04
6 External plaster
0.03
0.9
0.03
7 External thermal surface resistance
0.04
Overall thermal resistance (m
2
K W
-1
)
1.02
Thermal transmittance (W m
-2
K
-1
)
0.98
The building was divided into calculation conditioned zones at temperature of 20°C (see
Fig. 8):
•
first floor – Zone n. 1 (ground floor);
•
second floor – Zone n. 2;
•
third floor – Zone n. 3;
•
forth floor – Zone n. 4;
•
fifth floor – Zone n. 5.
The attic and the boiler room are unconditioned areas.
