measuring carbon footprint of your building supply chain

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

http://www.hkqaa.org/en_community.php?catid=2

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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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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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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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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Make the best decisions in the early project stage

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Source: Fieldson et al (2009)


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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Cradle-to-Grave Concept

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Source: Government of British

Columbia, http://www.gov.bc.ca/


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)


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


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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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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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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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


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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Bottom-Up Approach

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Source: PAS 2050: 2008


Life Cycle Emission Analysis

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Three Phases


Envisaged Carbon Label for Construction Materals

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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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http://www.prlog.org/10119688-care-about-the-planet.jpg


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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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: [email protected]

mailto:[email protected]

http://www.hkqaa.org/en_community.php?catid=2

measuring carbon footprint of your building supply chain

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