Civil Engineering Reference
In-Depth Information
where
• GWP
Building
is calculated with regard to the building life cycle (kgCO
2eq
);
• GWP
a, y
is the GWP avoided yearly in the Refurbishment scenario, which
results 24,492 kgCO
2eq
/y. It depends on the typology and efficiency of the used
plants. It is based on the previous E
s, y
and on the reference emission factor of
each electricity mix and national gas-fired heating plants.
The two indexes assessed for the case study are 14 and 8 years, respectively.
These outcomes involve that the energy and environmental benefits related to
Refurbishment scenario would fully repay the life cycle impacts in a short period
in comparison with the expected lifetime of the building itself.
4 Discussion and Conclusions
The above life cycle energy and environmental assessment aims to highlight the
variation of the ecoprofile of the LH, when it is shifted from nearly Net ZEB
toward the Net ZEB target, at final energy level.
Globally, in the Refurbishment scenario, all the life cycle energy and envi-
ronmental impact indicators present lower values than the Baseline scenario.
As it can be noted from the results, the production and the replacement give the
highest contribution on the building life cycle ecoprofile in both assessed sce-
narios, with regard to CED and the environmental indicators. They slightly
increase moving from the existing nearly Net ZEB to the refurbished Net ZEB.
Building operation results the most affected phase. In fact, when moving from
the Baseline to the Refurbishment scenario, the building not only reaches the
energy balance condition (E
net, LH
= 0), but also generates a surplus as final
energy (E
net, LH
[ 0). Then, the sum of the covered deficit from the nearly Net
ZEB to the Net ZEB condition and the energy surplus, which is assumed to be
exported to the grid, involves significant saving of primary energy and avoided
environmental impacts, depending on the Italian energy mix for the production of
electricity.
Therefore, the main conclusion of the presented study is that taking the step
from a nearly Net ZEB to Net ZEB results in a small increase in primary energy
consumption and environmental impacts in the production and maintenance steps,
while the operating energy demand goes down to zero. However, each energy and
environmental indicator results decreased and, consequently, the ecoprofile of the
refurbished building is globally improved with respect to the existing building.
Further, the surplus generation owing to the PV plant retrofit involves energy and
environmental benefits beyond the building boundary, in terms of primary energy
saving and avoided environmental impacts.
