environmental implications of steel bridge construction

2.1 Conversion factors
2.1.1 Machines and tools
For machines working on electricity, the total energy E is expressed by Eq. (1):
E = nϕ
λ P [ kWh]
(1.a)
or E = 3.6
nϕ
λ P [ MJ]
(1.b)
where:
P the declared power of the machine [kW];
n the total number of working hours reported by the operator [h];
λ the load factor, which is the percentage of the full capacity that has been used [%];
ϕ the effectivity, expressing the effective working time of the machine divided by the
reported working time of the operator [%].
The global warming potential GWP is expressed by Eq. (2), which is based on [4]:
GWP = 0.
615 E [ kgC02eq]
(2)
where:
E the total energy expressed by Eq. (1.a) in [kWh].
Typical values of the load factor λ and the effectivity ϕ are shown in Table 1.
Table 1: Typical values for the load factor and the efficiency
Load factor Effectivity ϕ
λ
Cranes (workshop) 50% 60%
Compressor (workshop) 30% 100%
Ventilation (workshop) 100% 100%
Plate oxy-cutting (workshop) 40% 100%
Drilling, punching, sawing (workshop) 60% 70%
2.1.2 Consumables (gas and other materials)
The energy consumption E and global warming potential GWP have been derived from the
recorded actual consumed quantities, using Eq. (3) to (13) which are based on [4] and [5]:
E = .6 c pr
m MJ
(3)
- For propane: 3
o pro
[ ]
3.
00m
pro
[ kgCO2eq]
- For natural gas: 3.6
c nat
v na t
[ MJ]
1.83
vnat
[ kgCO2eq]
- For acetylene: 3.6
c ace
vace
[ MJ]
2.
471d ace
vace
[ kgCO2eq]
- For diesel: 3.6
c die
vdie
[ MJ]
3.
135vdie
[ kgCO2eq]
- For thinners: .064v
[ kgCO2eq]
GWP = (4)
E = (5)
GWP = (6)
E = (7)
GWP = (8)
E = (9)
GWP = (10)
GWP = 0
thi
(11)
- For the zinc metal spray (ZnAl 85/15) process:
E = m MJ
(12)
68
met
4.80mmet
[ ]
[ kgCO2eq]
GWP = (13)
4