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Embodied Energy in Buildings
John Herbert
Director
The materials and components used to construct our buildings
require the use of different forms of energy. In the country
of origin, energy is used to mine, process, assemble, and
manufacture materials or products, they are transported to
to Hong Kong and then to job site.
Since that energy has been consumed, it is called embodied energy,
you can imagine it as a information tag permanently attached to
each material or product, and that embodied energy is tied with the
material or product forever, a key point that is often overlooked.
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.
Embodied Energy an important issue for areas like Hong Kong, that
must import 99% of its materials for construction from overseas, for
example, Hong Kong does not manufacture steel, it is all imported.
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 or products, for construction that
means the materials used to construct our buildings, in the Hong
Kong context, that predominantly means the raw materials for reinforced
concrete, and finished work such as steel, aluminium, and glass panels.
Other countries often use a much wider range of construction
materials during construction, however the general 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 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
from different countries, each with a different embodied energy
and the data is often difficult to obtain.
Then some materials for example concrete comprise raw materials
which could also be sourced from different countries. Often one project
will have steel and concrete materials from a number of countries, with
different production methods, travel distances and therefore different
embodied energy values.
Embodied Energy in Construction Waste
Its often overlooked, after the useful life of a product or material
it is often sent to landfill, including that is the embodied carbon and
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 and aggregate
- waste glass (cullet), a free resource, can be used as a raw material
for producing new glass, also used as replacement for silca for
producing and manufacturing concrete paving blocks;
- waste gypsum board, a free resource, can be used as a raw material
for creating new gypsum board (also known as dry board), gypsum can also
be used in agriculture as a conditioner added to soil;
There is a fixed quantity of naturally occuring gypsum, once its used
you can imagine a future with people digging up landfills to recover
the tonnes of buried gypsum.
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 (v1.2)
The EMSD LCA tool provides the calculation software to
estimate the embodied energy in Hong Kong building
structures, and BEAM PLUS 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,
BEFORE commencing the design, it is hoped that will encourage
and influence the choice of lower embodied energy materials
and products.
After the key decisions are made, repeating the embodied
energy calculation is a futile mathematical exercise.
For more information about our embodied energy reporting
call us today!
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