E n e r g y R e c o v e r y o f ‘ 7 0 e s I n d u s t r i a l i z e d B u i l d i n g
515
The "Technical Standards" of GESCAL predicted that the "thermal resistance" (R) of the
exterior walls had to be superior to 1 m²h°C/Cal (in the areas with a mean temperature in
January less than 4 °C) and superior to 0.9 m²h°C/Cal (in the areas with a mean
temperature in January more than 4 °C), while the "thermal resistance" of roofs and
floors above open spaces, in the two areas above-mentioned, had to be respectively
superior to 1.3 m²h°C/Cal and 1.2 m²h°C/Cal.
While the ministerial circular prescribed that the values of "thermal transmittance" (H),
equal to the inverse of the "thermal resistance", expressed as a function of the mean
weight of the wall (M), had to assume the following minimum values (Tab.1):
Table 1: Thermal transmittance values as a function of the mean weight of the wall
Vertical walls
M (kg/m
2
)
20
50
100
200
300
≥400
H (Cal/m
2
h°C)
0,43
0,61
0,81
1,09
1,35
1,40
Roof horizontal or inclined walls or overhanging porches and open spaces walls
M (kg/m
2
)
20
50
100
200
300
≥400
H (Cal/m
2
h°C)
0,30
0,45
0,60
0,81
1,00
1,15
Comparing the Gescal values with those of the Circular, it is clear that Table 1 valuesare
the same of those of the "Technical standards" of Gescal for the vertical walls weighting
168 kg/m
2
in the coldest areas and 208 kg/m
2
in the hottest ones.
This law was applied, only for subsidized housing, until 1976 when, due to the oil crisis,
the law dated 30/04/1976, No. 373 "Rules for the reduction of energy consumption for
heating in buildings" was enacted. This law, as amended and supplemented, and the
implementation decrees (Caleca, Cottone, 1983) were characterized by the following
parameters:
- Identification of six climatic zones as a function of the degree days;
- Determination of the "heat loss coefficient" (Cd) depending on the dispersing
surface - the heated volume ratio (S/V);
- Determination of the volume coefficient for each environment.
Afterwards, the law 09/01/1991 No. 10, "Rules for the implementation of national energy
plan in the field of rational energy use, energy saving and renewable energy sources
development," particularly the "TITLE II - Standard for the reduction of energy
consumption in buildings" introduced the compulsory energy certification of buildings. Its
implementation regulation was enacted only in 2005 and the Directive 2001/91/EC
allowed to achieve a coherent legislation for all EU countries, being implemented in Italy
with a Legislative Decree on 2005, repealing certain points of the Regulation of
contemporary law 10/1991.
The current values of transmittance, expressed in W/m
2
K, to benefit tax deductions are
reported below (Tab.2):
Table 2: Range of values for transmittance in the several zones of Italy
Climatic
zone
Degree
day
Vertical
walls
Roofs
Floors towards
non heated rooms
Windows
and casing
A
<600
0.54
0.32
0.60
3.7
B
C
D
E
F
601-900
901-1400
1401-2100
2101-3000
>3000
0.41
0.34
0.26
0.24
0.23
0.32
0.32
0.26
0.24
0.23
0.46
0.40
0.34
0.30
0.28
2.4
2.1
2.0
1.8
1.6
