Sustainable construction materials and assemblies for Nigerian low cost housing

Abstract

Sustainable construction is a way to achieve environmental-friendly building design and construction. Construction activity has impact on the environment and users of naturally occurring and synthesized resources. The recent rise in environmental conscious design mandates the development of a new tool for pre-use stage decision-making in the materials and assemblies process. It is crucial in building life-cycle decision making, to integrate environmental issues in the evaluation process. The study developed an evaluation-tool to aid in the pre-use stage decision-making process of low cost housing projects by integrating sustainable construction principles into the materials and assemblies process. The study identified the decision making tool; then investigated the environmental awareness issues in sustainable materials and assemblies at pre-use stage; and finally, evaluated and compared the pre-use stage overall environmental impacts of a building life cycle. An explanatory sequential mixed method research design was adopted. 43.1% of 480 architects and designers in Abuja-Nigeria, through stratified random sampling participated in the survey. Data were analysed using descriptive statistics analysis, relative index analysis and Kendall‘s Concordance. The findings showed the need for a new materials and assemblies tool for environmental impact evaluation, and designers do have the knowledge and are concerned about environmental issues of sustainable materials and assemblies. Based on the findings, an evaluation system was developed. Two case studies of a traditional construction method (TCM) and a contemporary construction method (CCM) for low cost housing were chosen to test the system. Data were analysed using linear programming coupled with a process life cycle assessment (LCA) framework and international energy and carbon protocols. The findings showed that the environmental performance of the building life-cycle pre-use stage can be improved by up to 126% embodied energy and 165% embodied carbon emissions. Furthermore, it was much easier to compare the environmental performances of whole-building assemblies, instead of separate materials and elements that do not represent the performance of the function of a building. The study has shown that the evaluation system provides design guidelines and criterion to achieve environmental conscious design. Based on the findings from the evaluation system, a decision-making tool, the Optimum Life Cycle Assessment Performance (OLCAP) was developed. This tool can be used to guide local authorities, academicians and stakeholders to develop a structure for effective implementation of pre-use stage sustainable materials and assemblies. The tool developed was validated by the application of REVIT. Furthermore, the tool exposes the true environmental and economic sustainability in materials and assemblies with the help of simple multiplication and REVIT, which is readily available in the market. As a conclusion, OLCAP, the tool developed in this research can reduce the environmental impact of design and construction.