Lifecycle Assessment LCA comparison for different prefabricated modular construction systems with the conventional construction system for affordable houses in Egypt
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Date
2017-02
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The British University in Dubai (BUiD)
Abstract
Egypt is considered as the most populated country in the Arab world with its high population that exceeds 94 million (CIA, 2017), 62.6% of them are in working age and the young generation forms 19.24% of the overall population. This overpopulation puts a huge pressure on many sectors including affordable housing which suffers from severe supply shortage. All conventional housing solutions that the different governments have put to solve this issue along the last 70 years, they are still fare away from being affordable to the majority of population in many cities in Egypt. This research focuses on studying the environmental viability of introducing prefabricated modular systems as an alternative sustainable solution to the current conventional construction system in affordable housing sector. To achieve the goals of this research, a comparison was conducted between four prefabricated and modular construction systems to the conventional construction system and studied their different impacts on the environment. The conventional construction system that is widely used in Egypt is cast in situ and masonry work. In this research, this conventional construction has been compared to the following four prefabricated construction systems: 1) Pre-cast Concrete PCC, 2) Glass Reinforced Concrete GRC, 3) Light Gauge Steel LGS, 4) Adapted Shipping Containers. Life Cycle Assessment (LCA) has been used as the research methodology to compare the environmental impact of the four construction system to the conventional system which was used as the base case for this comparison.
This research aims to assess these prefabricated systems that exist in Egypt and evaluate their impacts on environment from the perspective of the used resources and land emissions over the life-cycle of each system, total primary energy consumption and global warming potentials over the life cycle of the building. Five building models, one for each of the previous mentioned construction systems, have been designed and used in the LCA analysis. All the 5 models share the same physical dimensions and the same spatial components for the building under study but vary in their construction materials. The building is composed of a 4-storey building that holds 3 residential units per floor. Athena Impact Estimator was the software used for the LCA assessment tool and eQUEST was the energy analysis software used.
After running the LCA analysis we concluded that among the four construction systems and over the 50 years of their life cycle, both GRC and LGS options proved a lot of reduction in their impacts on environment. During the production and the construction stages as compared to the convention construction system, LGS and GRC reduced 66% and 46% of the used solid resources respectively. These reductions are due to the reduction in the materials mass used in these 2 construction systems. Accordingly and for the same reasons, the land emissions for the same systems (amount of waste generated along the life cycle of the building), have been reduced as well. LGS saved 60% while GRC saved 54% of the amount of waste that the conventional system produced. For the total primary energy consumption, LGS saved 40% of the total embodied energy compared to the conventional construction system while GRC saved 18%. For the Green-House Gas GHG emissions, LGS saved 64% while GRC saved 25% of the embodied emissions that the conventional system produced.
With their reduced environmental impacts, these two prefabrication systems are recommended to be used for the affordable housing projects in Egypt. Besides all the environmental benefits of these two systems, their prefabrication process in factories improves quality, reduces construction time and saves cost due to the economy of scale of the large housing projects especially those which are supported by the government.
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Keywords
Lifecycle Assessment (LCA), construction systems, affordable houses, Egypt, energy consumption