Civil Engineering Reference
In-Depth Information
• Eutrophication potential (EP).
• Photochemical ozone creation potential (POCP).
Furthermore, the following payback indices were added to the above EPD set
for a deeper description of the energy performance of the retrofit actions and to
compare different alternatives:
• Energy Payback Time (E
PT
) of a building retrofit action, which indicates the
time needed to save as much energy (valued as primary) as that consumed
during all the life-cycle phases of each retrofit component/material/technology,
• Emission Payback Time (Em
PT,GWP
), which indicates the time during which the
avoided GWP by the application of the retrofit actions is balanced by that one
derived from the life-cycle of each retrofit component (PRè
2010
),
• Energy return ratio (E
R
), which shows how many times energy saving exceeds
global energy consumption. It includes GER and the primary energy saving
induced by the retrofit actions during the whole building life cycle.
In detail, E
PT
was assessed for each action as:
E
PT
¼
GER
=
E
s
;
y
ð
1
Þ
where
• GER is calculated with regard to the life cycle of the retrofit action (GJ).
• E
s,y
is the yearly saving of primary energy due to the retrofit action (GJ/y).
The yearly direct saving of electricity and heat was estimated at the design
stage of the retrofit actions or measured after the retrofit was completed (Table
3
).
Such data were converted into primary energy based on the energy mix for the
production of electricity and other energy sources for each considered country
(Frischknecht et al.
2007
). Em
PT,GWP
was defined as:
Em
PT
;
GWP
¼
GWP/GWP
a
;
y
ð
2
Þ
where
• GWP is calculated with regard to the life cycle of the retrofit action (kgCO
2
eq).
• GWP
a,y
is the GWP avoided yearly after the retrofit (kgCO
2
eq/y). It also rep-
resents the GWP, which arises from the building if no retrofit action performed.
Table 3 Service life of each
retrofit component
Component
Lifetime (years)
Lighting equipments
3
Small wind turbines
15
HVAC systems
15
Solar thermal plants
15
PV plants
20
Building components
35
