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Measuring Carbon Footprint of
Your Building Supply Chain
Dr. S. Thomas Ng
Dr. James M.W. Wong
Department of Civil Engineering
The University of Hong Kong
HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Contents
Building supply chain and carbon footprint
Carbon footprint of typical building materials
Ways to measuring the carbon footprint
A glimpse of an on-going research project at HKU
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HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Why Bother ?
The Kyoto Protocol – aimed at fighting global warming by reducing
greenhouse gases
Hong Kong‟s Target – to reduce carbon intensity by 50-60% by 2020
compared with 2005 levels
Building sector contributed to 56% of final energy consumption in Hong
Kong in 2008 (EMSD, 2010)
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HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Current Perception
“… a zero energy house is one equipped with
photovoltaic panels and wind turbines; insulated with
sheep‟s wool; and without using PVC …”
“… reducing CO2 emissions at operation stage would
suffice as most of the sustainability regulations and
assessment models focus on this only …”
“… just how much carbon is generated in assembling
and disposing building components …”
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HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Reality
Embodied energy of a building may
constitute 15% of its lifetime energy
consumption (Harris, 1999)
In domestic buildings, embodied energy
may be equivalent to 10 times annual
operational energy use
For complex commercial buildings, the
ratio can be as high as 30:1 (Rawlinson
and Weight, 2007)
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HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Make the best decisions in the early project stage
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Source: Fieldson et al (2009)
HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Embodied Carbon
“The embodied carbon of a building material can be taken as the total carbon
released over its life cycle
This would normally include (at least) extraction, manufacturing and
transportation
Ideally the boundaries would be set from the extraction of raw materials until
the end of the products lifetime (including energy from manufacturing,
transport, energy to manufacture capital equipment, heating & lighting of
factory, maintenance, disposal, etc.)
known as „Cradle-to-Grave‟”
Inventory of Carbon & Energy (ICE, 2008)
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HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Cradle-to-Grave Concept
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Source: Government of British
Columbia, http://www.gov.bc.ca/
HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Embodied Carbon of Common Building Materials
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Materials Embodied Carbon (kgCO2/Kg)
Aluminium 11.46 (1.69 for recycled aluminium)
Steel (virgin) 2.75 (0.43 for recycled steel)
PVC 2.41
Glass 0.85
Cement 0.83 (0.42 for cement with 50% fly ash replacement)
Plywood 0.81
Lime 0.74
Tile 0.59
Bricks 0.22
Concrete 0.13 cement: sand: aggregate – 1:2:4
(0.209 for high strength concrete; 0.215 for prefabricated
concrete)
Plaster 0.12
Aggregates 0.005
Source: Inventory of Carbon & Energy (ICE, 2008)
HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Examples of Green Materials
Green block wall system
Can be recycled after demolition, even just by heat
and pressure after buried underground
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Source and Photo courtesy: Hong Kong Green
Council and CaSO (HK) Engineering
Photo courtesy: Technology Review
(http://www.technologyreview.in/energy/2
5300/)
Green Concrete
Reduce cement content reduce heat release
during curing, better concrete performance and
less carbon emission from cement production
Use recycled industrial by-products such as silica
fume/flyash to replace cement reduce cement
production yet achieving high strength
High performance green concrete reduce the
use of concrete and therefore related carbon
emission
HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Life Cycle Assessment (LCA)
“Carbon footprint of products or services needs to be calculated according
to an agreed standard”
Fieldson et al (2009)
The task of calculating carbon footprints can be approached
methodologically from two different perspectives:
Top-down – based on Environmental Input-Output (EIO) analysis using
national or organisational financial statistics
Bottom-up – based on Process Analysis (PA) in Life Cycle Analysis
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HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Top-Down Approach
Many countries produce inter-industry specific datasets (i.e. I/O table)
Such tables can be converted from monetary (input) values to energy basis
The sum of direct energies for various sectors then adds up to the
embodied energy / carbon in specific outputs (products) of that industry
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HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Bottom-Up Approach: Relevant Standards
ISO standards
ISO LCA standards (14000 and 14044) aim to establish a global industry wide
set of protocols to ensure that LCA studies are conducted in a comprehensive,
consistent and reproducible manner
ISO 14025 „Environmental labels and declarations‟ offers critical aspects on the
communication of LCA results
ISO 14040:2006 describes the principles and framework for life cycle
assessment (LCA)
ISO 14064 (1-3) Greenhouse Gases specifies guidance for quantification,
monitoring reporting & verification of GHG at organisational and project levels
ISO 14065:2007 specifies accreditation requirements for organisations that
validate or verify resulting GHG emission assertions or claims.
ISO 14067 is a developing standard designed to be a two-part international
guidance on quantification and communication of carbon footprints of products.
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HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Carbon footprint of building supply chain can
be measured based on ISO 14040:
Identifying construction materials to be
labelled (e.g. reinforcement bar)
Inventory assessment – Life Cycle
Inventory (LCI) data from relevant databases
with localization adjustment (e.g.
replacement of fuel mix, impacts of
transportation)
Assessing life cycle carbon emission
standard of studied construction materials
Interpretation and application –
benchmarking
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Bottom-Up Approach: ISO 14040
HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Bottom-Up Approach: PAS 2050
PAS 2050
Developed by the British Standard Institute and
co-sponsored by the Carbon Trust and Defra
PAS 2050 is a voluntary standard that has
been designed to help organisations assess,
manage, and reduce carbon footprints
The most applicable standard as it aims to
foster a greater understanding of the GHG
implications of purchasing decisions
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HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Bottom-Up Approach
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Source: PAS 2050: 2008
HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Life Cycle Emission Analysis
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Three Phases
HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Envisaged Carbon Label for Construction Materals
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HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
Is a Carbon Labelling Scheme for the
Building Sector Needed?
Importance of a universally recognised measurement unit
Promote selection of environmentally responsible options
Encourage manufacturers to improve relentlessly
Putting Hong Kong at the forefront of sustainable development as well as
accreditation service and carbon auditing
Achieving the Chief Executive‟s policy direction and tie in with the mission of
the Green Building Council
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HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
The Way Forward
New buildings vs. existing properties
In HK almost 90% of various end use of electricity is attributed to our
buildings (EPD, 2010)
In 2008 alone, the total energy consumed by the building sector was
36,845 million kWh or 24 million tonnes of CO2e (EMSD, 2010)
Strengthen existing environmental impact assessment methods i.e. BEAM
Plus, LEED, BREEAM, etc.
Set suitable policies to maximise the emission reduction opportunities in the
building sector
3 envelop system
Carbon trading
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HKQAA Symposium 2010 Measuring Carbon Footprint of Your Building Supply Chain
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END OF PRESENTATION
Thank you for your attention!
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Dr. S. Thomas NgAssociate Professor
Department of Civil Engineering
The University of Hong Kong
Email: tstng@hku.hku
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