Figure 1 : Study scope and boundary ( red dotted line )
The construction value chain assessment is the main scope of this study and encompasses material extraction , material manufacturing , transportation of material , and construction activities . This value chain ’ s boundary condition is commonly referred to as “ Cradle-to-Site ” ( Figure 1 ). “ Cradle-to-Site ” is an extension of “ Cradle-to-Gate ,” and further includes transportation from the factory gate to the construction site , including activities at construction sites during the construction stage .
The cradle-to-site GHG emissions can be categorised into three groups , as tabulated in Table 1 .
For this study , 14 construction materials were selected and prioritised for the cradle-tosite analysis . The nine major and five non-major construction materials are tabulated in Table 2 .
Under this study , a survey was carried out with selected contractors based on the construction project value to verify further and support the input values and assumptions used in the GHG assessment . In terms of composition for major material consumed by the construction sector , the results from the survey of actual projects are comparable to the data compiled from CIDB and other sources ( Table 3 ).
GHG Emission Aspects
Embodied Carbon in Material 1 . Demand for construction materials such as cement , concrete , steel reinforcement , etc .
Transportation of Material 2 . Distribution of construction material to the construction site
Emissions at Construction Site 3 . Use of equipment and machinery during construction , maintenance , and renovation as well as waste generated from the construction site
Main Sources of GHG Emissions
This material consumes energy and produces GHG during the extraction and manufacturing process , commonly referred to as Embodied Carbon ( cradle-togate ).
The transportation of construction material to the site consumes fossil fuel , such as diesel . GHG emissions from transportation of material included GHG emissions from the production , processing , and delivery of fuel ( Well to Tank ) and fuel combustion .
The construction stage utilises various machinery and equipment which consume fossil fuel and / or electricity . GHG is also emitted from the disposed degradable waste . The GHG emissions from fossil fuel utilisation from machinery and equipment include GHG emissions from production , processing , and delivery of fuel and fuel combustion .
Table 1 : GHG emissions contribution from the construction industry
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