G r e e n R o o f s a s P a s s i v e C o o l i n g S t r a t e g i e s
591
roof in the summer period, also comparing it with other types of roof coverings, when
installed on roof slabs that are strongly insulated in accordance with the present Italian
regulation on energy saving in the construction industry.
Materials and methods
The research was carried out by comparing the thermal performance of an extensive
green roof with that of 4 other types of roofs in terms of covering and under covering
ventilation.
All of them were installed on a real-scale experimental building in the vicinity of Ancona
(Italy, 2064 DD).
The building was 8.20 x 10.50 m, totalling 82.30 m
2
with a unique volume of around 250
m
3
, which created a realistic attic. The S/V ratio was 0.89. The side walls were built with
multi-layered insulating panels made of polyurethane resin (U=0,20 W/m
2
K). Inside the
envelope, a 30 cm air cavity was created with the help of 22 mm OSB panels in order to
reduce the impact of solar radiation on the walls. The floor was insulated with
polystyrene panels in order to make the building almost adiabatic (U=0,33 W/m
2
K).
The roof was divided into 6 modules of roofs of the same width (1.50 each) and same
length of 6 m on the south slope and 3 m on the north slope, in order to obtain a similar
size as that of traditional roofs (Fig.1).
Figure 1: External view of the experimental building near Ancona (Italy): north roof slope
The roofs, in pairs, were different from each other in terms of the kind of slab (made of
wood or concrete), type of roof covering (copper or clay tiles) and the type of under
covering ventilation (ventilation absent, 3 or 6 cm air cavity). Fig. 2 shows the
stratigraphies which are the focus of the present study (roofs on wooden slab: types
1,2,3,4).
The common element among all the roof coverings is the insulation, which was made of
two crossed layers of EPS panels with a total thickness of 12 cm (U=0,25 W/m
2
K). In
order to avoid heat transmission in between the modules, the paths of connection were
also insulated with EPS panels that were positioned vertically.
