An Enhanced Comparative Life Cycle Assessment Approach for Evaluating The Energy Consumption and Carbon Emissions of Prefabricated Construction Methods

Construction is one of the largest industries which have a significant impact on the environment. It is known that concrete has been the second most consumed material - only after water - in the world for years. It has been estimated that buildings and construction account for 37% of energy related carbon emissions. One way to reduce carbon footprint, is to utilise materials which require less energy to be produced such as modular construction, prefabricated materials, and recycled materials. The adoption of prefabricated construction techniques has been increasing to reduce carbon emissions. In the design phase of construction projects, a comparative life cycle assessment (LCA) is conducted to select the best construction method from two or more alternatives. While the original LCA framework is considered too broad, typical comparative LCA studies focus on the materials and construction activities involved in each method. However, each construction method has specific characteristics that necessitate or avoid certain materials or activities. It has been evident that the majority of previous studies usually focus only on the directly involved factors such as the direct materials of the construction methods and miss to include some indirect items which can be extremely vital in the assessment. As the original LCA is too broad, many items can easily be overlooked and neglected, which can be extremely detrimental for the overall evaluation and may lead to false results. A prime example of the items that usually get overlook is the required maintenance aspect of the construction method. Another example is the carbon emissions resulting from labour transportation, which entirely dependent on the speed of the construction method. This study proposes an enhanced and applicable framework that has been developed from the original one. It has been developed by examining the features of different construction methods to outline the dependent materials and construction activities then categorising each phase of the LCA into direct (independent) and indirect (dependent) carbon emission factors. Polymer Profile Walling and Traditional Concrete Wall construction methods were examined to demonstrate how the proposed comparative LCA framework can be utilised. Energy consumption and carbon emissions were quantified for each method and a comparison was made. Polymer Profile Walling has been selected as a case study due to its wide usage, in addition to the fact that walling elements are significant components in buildings. An Australian based Polymer Profile Walling manufacturer and an experienced builder were engaged in this research to provide their insights and required data. Data were collected from the engaged manufacturer and builder, in addition to various sources including suppliers, manufacturers, published reports by Australian Government, etc. Structural drawings were collected from the manufacturer and wall measurements were carried out by using iTWO costX software. Wall materials’ quantities such as concrete and steel reinforcement were calculated for each construction method based on the relevant structural specifications found on the structural drawings. Consequently, the embodied energy and carbon amounts were quantified by multiplying each material quantity by its relevant factor from The Environmental Performance in Construction (EPiC) database. Regarding the energy consumption and carbon emissions resulting from fuel consumption, the required fuel quantities were also calculated for each method and multiplied by the relevant energy consumption and carbon emissions factors, and the total amounts were quantified for each method. Overall, it was found that the Polymer Profile Walling construction method consumes less energy by 18.42% and achieves up to 25.9% reduction in carbon emissions. The significant reduction in carbon emissions was mainly due to the Polymer Profile Construction method ability of eliminating several building materials, construction equipment, and transportation activities. Although the Polymer Profile Walling construction method utilises PVC material, which is known to be harmful towards the environment, yet overall, it had the lower impact. This clearly highlights the importance of incorporating all the direct as well as the indirect factors in the assessment. This study has theoretically contributed to knowledge by developing an enhanced comparative LCA framework that accounts for indirect (dependent) materials and construction activities which can fundamentally change the overall results. Practically, this study has a significant contribution by calculating the energy consumption and carbon emissions of Polymer Profile Walling construction method and comparing it against the conventional concrete wall. Furthermore, the research contributions of this study are also aligned with sustainable development goal (SDG) 11 “Sustainable Cities and Communities” as with the utilisation of the developed comparative LCA framework, decision makers can select more sustainable materials and construction methods which would create more sustainable buildings and infrastructure which results in making cities more sustainable. In addition, as this study has recommended the use of Polymer Profile Walling, utilising such innovative products would lead to the elimination of many other materials and construction activities as illustrated in this study which aligns with SDG 12 “Responsible Consumption and Production”. There are few research limitations of this study such as not including the end of life phase in the assessment due to the limited data available, adopting only one case study due to the intensive analysis and calculations involved, and allowing a unified the distance for all labour and materials’ transportation. Future research can focus on investigating the impact of the end-of-life phase and explore recycling methodologies. Further research is also required to examine the environmental impact of using a swinging stage against traditional scaffolding. Additionally, research is also required to investigate how changing the structural frame system from columns to load bearing walls can result in massive savings in material quantities and carbon emissions.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2024

Author dc:creator

• Salih, Hadi

• Life Cycle Assessment
• Prefabricated Construction
• Carbon Emission
• Energy Consumption
• Embodied Carbon
• Construction Methods
• anzsrc-for: 330202 Building construction management and project planning
• anzsrc-for: 400504 Construction engineering

Statement dc:rights

• open access
• CC BY 4.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by/4.0/

Language dc:language

en

Identifier

https://doi.org/10.26190/unsworks/30871

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/104145