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
139
It is certainly more useful to know the energy need per cubic meter that, in this case, is
equal to 64,9 MJ/m
3
. The Figure 10 shows the trend of the energy need per cubic meter
during the heating season.
Figure 10: Percentage distribution of energy need for heating
The school is equipped with an air conditioning system consisting of a AHU, air ducts, air
outlets and a boiler fueled by natural gas. The boiler room is located on ground floor.
The efficiencies of the four subsystems that constitute the HVAC system are:
•
0.9 for the emission system (air inlet);
•
0.93 for control system (on/off type);
•
0.938 for distribution system;
•
0.86 for generation system (boiler).
The electrical energy need for auxiliary equipment of air conditioning system is equal to
828.34 kWh
el
, that is equal to 1837.11 kWh (converted to primary energy), instead the
primary energy use for winter heating is equal to 378774.45 kWh.
The average seasonal efficiency of the air conditioning system for winter heating is
supplied by following relation:
ℎ
=
ℎ, ,ℎ
= 0.672
where:
•
Q
h,env
is the energy need for heating with reference to the building envelope
(equal to 916217MJ or 254504.76 kWh);
•
Q
p,h
is the energy use for winter heating (equal to 378774.45 kWh);
The Energy Performance index for the winter heating is supplied by following equation:
ℎ
=
ℎ,
ℎ
∙
= 26.82 kWh m
3
where:
V
gross
is the gross volume of the school building (equal to 14124.08 m
3
).
According to the “D.Lgs 192/05” Italian law [20], the Energy Performance index for the
winter heating of this building should not exceed 4.78 kWh/m
3
.
0
5
10
15
20
25
Dec
Jan
Feb
Mar
Energy need per cubic meter
