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Embodied Energy in Buildings
John Herbert
Director
The materials and components used to construct our buildings
required the use of different forms of energy, in the country
of orgin, to mine, process, assemble, and manufacture materials
and ship to the job site. Since that energy has been used, we
call it embodied energy. That energy used is tied to the product
or material, from factory door to its grave.
Presently, there is no standard framework used in Hong Kong
to assess Embodied Energy or Embodied Carbon, only the EMSD
LCCA tool can be used to calculate the embodied energy, and
therefore implicitly the embodied carbon.
Like it or not, sustainability and energy are two sides of
the same coin.
Embodied Energy
The term Embodied Energy is meant to reflect the energy consumed
during production of materials, for construction that means the
materials used to construct our buildings, in the Hong Kong context,
that predominantly reinforced concrete, glass and steel.
Other countries often use a wider range of construction
materials, but the principle is the same.
The production of the concrete, glass and steel require vast
quantities of energy, and emit carbon dioxide emissions
during those processes.
In Hong Kong there are no steel factories, so all the steel
building materials are generally imported.
For buildings using reinforced concrete, the components are
mixed either 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 materials for making concrete are energy intensive,
but are typically produced overseas and shipped to Hong Kong, therefore
the resulting carbon emission does not appear as a local emission,
but the energy/carbon used is tied to the material, and embodied
energy / embodied carbon is the term used to define those emissions.
In a perfect world all the materials would arrive with emodied energy
label, totalling up those figures provides the emodied energy figure,
but real life is rarely that straightforward.
One element for example steel, can be provided by different factories
in different countries, each with a different embodied energy
and the data is often difficult to obtain.
Then some materials for example concrete comprise several different
elements, which could also be sourced from different countries.
Often one project will have steel and concrete materials from a
mumber of countries, with different production methods and travel
distances.
Embodied Energy in Waste
Its often overlooked, after the useful life of a product or material
it is sent to landfill, including that 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
chosen, a bonus point is awarded.
Its true, the 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.
However, giving the embodied energy data to the designer,
it is hoped that will encourage and 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!