Life cycle impact comparison of different concrete floor slabs considering uncertainty and sensitivity analysis

The traditional construction industry is characterized as a labor-intensive, wasteful, and inefficient sector. Currently, prefabrication has become a common practice in residential development and has reduced energy consumption and waste generation compared to traditional on-site practices. This study investigates the differences in life cycle environmental impacts among three different floor systems (precast slab, composite slab (semi-precast slab) and cast-in-situ slab) based on two functional units (delivering the same carrying capacity and maintaining consistent floor depth) using both LCA midpoint and endpoint methods using the software tool SimaPro. This study sets a calculation boundary for the construction process: raw material production, slab production, transportation, construction activities on-site, demolition and recycling of buildings at the end-of-life stage. Moreover, uncertainty and sensitivity analysis are carried out to help decision-makers identify major environmental impact factors and develop eco-friendly plans to facilitate housing industrialization. The results indicate that (1) the environmental impact of precast slab outperforms those of cast-in-situ and composite floors regardless of different design functional units and evaluation methods. (2) While under different functional units, the environmental performance of composite and cast-in-situ floors varies considerably. (3) From the perspective of life cycle stages, the transportation sector and its supply chain make up a significant portion of the final environmental impact and are responsible for 45.2%, 50.1% and 53.6% of the total impact for the precast, composite and cast-in-situ slabs, respectively. Slab production of precast slab (it is raw material production of cast-in-situ and composite slabs) is the second largest contributor to the environmental impact

Investigation into contractors' responsible sourcing implementation practice

This article was published in the journal Proceedings of the ICE - Engineering Sustainability [© Institution of Civil Engineers]. Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees. The journal's website is at: http://www.icevirtuallibrary.com/content/serial/ensuOver the last few years there has been an increasing demand for more efficient ways of procuring materials in terms of reducing their impacts on the environment. The UK Strategy for Sustainable Construction introduced a voluntary target of 25% of all resources in the construction industry to be responsibly sourced by 2012. At the time of writing there has been very limited research on responsible sourcing (RS), particularly in terms of contractors' current practices and implementation at project level. Therefore, an assessment of the current status of RS among the top 100 UK contractors has been captured using a questionnaire survey and follow-up interviews. The results indicate that no clear RS responsibility has been established, and there is no cohesive, top-down strategy from the strategic level (sustainability managers) to the implementation level (procurement mangers) in place in contracting companies. On the other hand, there was agreement that government leadership through the implementation of RS in all public projects could be a significant catalyst to drive RS in construction projects