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Embodied Energy in building construction Hong Kong
John Herbert
Director
The materials and components used to construct Hong Kong buildings
require the use of different forms of energy use. In the country
of orgin, energy is used to mine, process, assemble, and manufacture
materials, and then ship to the job site.
Since that energy has been used before arriving in Hong Kong, we call it
embodied energy (and the related embodied carbon). That energy used is
tied to the product or material, forever, from factory door to the
grave.
Presently, there is no standard framework used in Hong Kong
to assess Embodied Energy or Embodied Carbon, the EMSD LCCA tool
can be used to calculate the embodied energy, and implicitly the
embodied carbon.
Like it or not, sustainability and energy are two sides of
the same coin.
Embodied Energy in Hong Kong Structures
The term Embodied Energy is meant to reflect the energy consumed
during production stage of materials for the construction
of buildings. In the Hong Kong context, that means the materials
are IMPORTED, predominantly the raw materials for reinforced
concrete, and completed components such as aluminium curtain
wall units, glazing panels, etc.
During the production of the cement, glass, and steel vast
quantities of energy are used, and the related carbon
dioxide is emitted overseas, so is not counnted within Hong
Kong's emission inventory.
There are few industries remaining in Hong Kong therefore
the majority of construction materials and constituent raw
materials are imported from overseas, included the embodied
energy and implicitly the embodied carbon.
However, the emission factor overseas for energy use,
electricity production, etc. can be significantly higher
than Hong Kong, which causes under reporting of the real
emission.
For buildings using cast-in-situ reinforced concrete, its
constituents are imported, then either mixed on site in a
batching plant (for large projects) or mixed in a central
concrete plant and transported using concrete trucks to
the site.
Embodied Carbon and Production
Steel and the constituents materials for production of cast-in-situ
concrete are energy intensive, the raw materials typically produced
overseas and shipped to Hong Kong, therefore the resulting carbon emission
does not appear as a "local" emission, so Hong Kong GHG inventory
appears lower.
In a perfect world, all materials would arrive in Hong Kong with a clear
embodied energy label, totalling up those figures would provide the total
embodied energy figure, but real life is rarely that straightforward.
For example steelwork, steel can be provided by different factories,
from different countries, each with a different embodied energy quantity
but often the data is difficult to obtain.
Then some materials for example concrete comprise several different
elements, which maybe be sourced from different countries.
Often one project will have steel products and concrete materials
from a number of countries, with different production methods, and
different travel distances.
Embodied Energy in Hong Kong Waste
Its often overlooked, after the useful life of a product or material
it is sent to landfill, including the embodied energy used in its
production. Therefore, use of post consumer waste including post-building
waste, is important, where possible materials should be repurposed, some
examples:
- waste concrete, a free resource,can be used as a raw material for
producing new concrete paving blocks (pioneered in Hong Kong);
- waste glass (cullet), a free resource, can be used as a raw material
for producing new glass, and used as replacement for silca for
producing concrete paving blocks;
- waste gypsum board, a free resource, can be used as a raw material
for creating new gypsum board, and can be used as a conditioner
added to soil;
With the expertise to back this up, for example specifying
energy, water and waste efficient techniques and equipment in
buildings and infrastructure and the specialist analysis
techniques to demonstrate the practical environmental
performance.
BEAM PLUS EU3 Embodied Energy
The EMSD LCA tool provides the calculation software to
estimate the embodied energy in Hong Kong building
structures, and BEAMPLUS New Building, credit EU3,
encourages embodied energy assessment at the concept
stage, giving vital knowledge to designers before key
decisions are made.
Under BEAM PLUS EU3, if two or more options are examined,
and the option having the lowest embodied energy is
choosen, a bonus point can be earned.
Whilst it is true that embodied energy in a structure
can be calculated at different stages of the project,
it is the same for embodied carbon, even years later
after the project is complete the embodied energy can be
calculated, it is too late to influence the design.
However, giving the embodied energy data to the designer early,
it is hoped that will influence the choice of materials BEFORE
commencing the design. After the key decisions are made,
repeating the calculation is a futile mathematical exercise.
For more information about our embodied energy reporting
call us today!
More Information
Building Embodied Energy
Building Embodied Carbon
E&M Condition Survey
infrared inspection
REA energy audit
energy modelling
carbon audit
carbon auditor
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