Civil Engineering Reference
In-Depth Information
Type of transport
MJ/ton/km
Diesel: road transport
1.6
Diesel: sea transport
0.6
Diesel: rail transport
0.6
Electric: rail transport
0.2
Energy consumption during building, use and demolition
Transport and the use of completed products is usually about 20 per cent of the
total energy input.
•
Energy consumption for the transport of manufactured products
. This can have a
very decisive role in the total energy picture. One example is the export of
lightweight concrete elements from Norway to Korea, which uses over
10 000 MJ/m
3
, while the actual manufacture of the elements require a prima-
ry energy input of 3500 MJ/m
3
. This confirms the principle that heavy materi-
als ought to be used locally.
•
Energy consumption on the building site
. This includes consumption which is
already included within the tools used, heating and lighting, plant, electricity
and machines. It also includes the energy needed to dry the building con-
struction such as in-situ concrete. The use of human energy varies from mate-
rial to material just as it varies between the manufacture and use of a materi-
al. This will not have much of an impact on the overall picture. Assuming one
person uses 0.36 MJ energy per hour, a single house would consume
270-540 MJ.
The amount of energy used on the building site has grown considerably in
recent years as a result of increased mechanization. Drying out of the building
with industrial fans is relatively new. Traditionally the main structure of the
building, with the roof, is completed during spring, so it could dry during the
summer break. The moisture content of the different building materials also
affects the picture. For example, it takes twice as long to dry out a concrete
wall as it does a solid timber wall.
•
Energy consumption during maintenance
. Sun, frost, wind, damp, human use etc.
wear away the different materials, so that the building needs to be maintained
and renovated. Initially one treats the surfaces by painting or impregnation,
materials that have an energy content themselves. The next stage is replace-
ment of dilapidated or defective components.
•
Energy consumption of dismantling or removal of materials during demolition
. This
is approximately 10 per cent of the energy input which is integral within the
different materials.
