Quantifying the environmental dimension of sustainability for the built environment : with a focus on low-cost housing in South Africa

[摘要] ENGLISH ABSTRACT: Sustainability is difficult to achieve in a world where population and economic growth leads toincreased production of greenhouse gases, resource depletion and waste generation. Today, theenvironmental dimension of sustainability, which is more commonly known as the naturalenvironment, and the construction industry are two terms often mentioned together. In Europe,12.4 % of greenhouse gas emissions are induced by the construction and manufacturing industry(Maydl, 2004). Also, 50 % of the resources extracted are used in the construction industry and morethan 25 % of waste generated is construction and demolition waste. In South Africa, the buildingsector accounts for approximately 23 % of the total greenhouse gas emissions (Milford, 2009).Furthermore, 60 % of investment is made in the residential sector where 33 % of the building stock isthe focus of the government's Housing Programme. It is seen that the construction industrysignificantly impacts the natural environment and the aim should be to reduce this negative impact.Within the local residential sector, the low-cost housing sector presents potential when it comes tosustainable improvements. Each of the three spheres of sustainability, namely economy, naturalenvironment and society, plays a crucial role in this sector. Various studies have been done on theeconomical and social fields, but little information exists on the impact low-cost houses have on theenvironment. A need arises to scientifically quantify the environmental impact hereof, therefore it ischosen as the focus of this study.Various methods in order to determine the environmental impact of the built environment existglobally, but they tend to be complex, are used in conjunction with difficult to understand databasesand require expensive software. A need for a local quantification method with which to determine theenvironmental impact of the built environment, more specifically low-cost housing, has beenidentified. A simple and easy-to-use analysis-orientated quantification method is proposed in thisstudy. The quantification method is compiled with indicators related to the local conditions; theseinclude Emissions, Resource Depletion and Waste Generation. The end objective is to provide theuser with an aggregated total value called the Environmental Impact Index to ease comparison ofpossible alternatives.The quantification method is developed as a mathematical tool in the form of a partial Life CycleAssessment which can aid in objective decision making during the conception and design phase of aspecific project. Note that only the Pre-Use Phase of the building life cycle is considered during theassessment, but can be extended to include the Use Phase and End-of-Life Phase. The proposedmethod has the capability of calculating and optimising the environmental impact of a building.Regarding low-cost housing, different housing unit designs can be compared in order to select the bestalternative.The quantification method is implemented for two low-cost house design types in this study. Firstly,the conventional brick and mortar design is considered whereafter a Light Steel Frame Building isviewed as an alternative. The model implementation demonstrates that the model operates in itssupposed manner. Also, Light Steel Frame Building housing units are shown to be worthinvestigating as an alternative to the conventional brick and mortar design but should be confirmedwith a more accurate Life Cycle Assessment.

[发布机构] Stellenbosch University