Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Sustainability is difficult to achieve in a world where population and economic growth leads to increased production of greenhouse gases, resource depletion and waste generation. Today, the environmental dimension of sustainability, which is more commonly known as the natural environment, 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 more than 25 % of waste generated is construction and demolition waste. In South Africa, the building sector 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 is the focus of the government’s Housing Programme. It is seen that the construction industry significantly 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 to sustainable improvements. Each of the three spheres of sustainability, namely economy, natural environment and society, plays a crucial role in this sector. Various studies have been done on the economical and social fields, but little information exists on the impact low-cost houses have on the environment. A need arises to scientifically quantify the environmental impact hereof, therefore it is chosen as the focus of this study. Various methods in order to determine the environmental impact of the built environment exist globally, but they tend to be complex, are used in conjunction with difficult to understand databases and require expensive software. A need for a local quantification method with which to determine the environmental impact of the built environment, more specifically low-cost housing, has been identified. A simple and easy-to-use analysis-orientated quantification method is proposed in this study. The quantification method is compiled with indicators related to the local conditions; these include Emissions, Resource Depletion and Waste Generation. The end objective is to provide the user with an aggregated total value called the Environmental Impact Index to ease comparison of possible alternatives. The quantification method is developed as a mathematical tool in the form of a partial Life Cycle Assessment which can aid in objective decision making during the conception and design phase of a specific project. Note that only the Pre-Use Phase of the building life cycle is considered during the assessment, but can be extended to include the Use Phase and End-of-Life Phase. The proposed method 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 best alternative. 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 is viewed as an alternative. The model implementation demonstrates that the model operates in its supposed manner. Also, Light Steel Frame Building housing units are shown to be worth investigating as an alternative to the conventional brick and mortar design but should be confirmed with a more accurate Life Cycle Assessment. / AFRIKAANSE OPSOMMING: In ’n wêreld waar toenemende ekonomiese en bevolkingsgroei veroorsaak dat al hoe meer kweekhuisgasse voortgebring word, hulpbronne uitgeput word en groter hoeveelhede rommel geproduseer word, is dit ’n bykans onbegonne taak om volhoubaarheid te probeer bereik. Volhoubaarheid rakende die natuurlike omgewing en konstruksie is twee terme wat vandag dikwels saam genoem word. Ongeveer 12.4 % van die kweekhuisgasse wat in Europa vrygestel word kom uit die konstruksie- en vervaardigingbedrywe (Maydl, 2004). Die konstruksiebedryf gebruik ook bykans die helfte van hulpbronne wat ontgin word en meer as 25 % van rommel word deur konstruksie of sloping produseer. Die Suid-Afrikaaanse boubedryf is verantwoordelik vir 23 % van die totale hoeveelheid kweekhuisgasse wat die land vrystel. Die behuisingsektor, waar die regering aan die hoof van 33 % van eenhede staan, ontvang 60 % van bestaande beleggings (Milford, 2009). Dit is dus duidelik dat die boubedryf ’n negatiewe impak op die natuurlike omgewing het en dat dit van groot belang is om dié situasie te verbeter. In die behuisingsektor het lae-koste-behuising groot potensiaal as dit kom by volhoubaarheid. Volhoubaarheid bestaan uit drie sfere: ekonomie, natuurlike omgewing en sosiaal, en al drie speel ’n betekenisvolle rol in lae-koste-behuising. Daar is reeds verskeie studies aangepak om die ekonomiese en sosiale sfere te beskryf, maar daar is steeds min inligting beskikbaar oor die omgewingsimpak van ’n lae-koste-huis. Dit laat die behoefte ontstaan om hierdie impak te kwantifiseer. Bestaande metodes wat wêreldwyd gebruik word om ʼn omgewingsimpak te bepaal is dikwels besonder kompleks en benodig duur sagteware tesame met ingewikkelde databasisse om dit te implementeer. ’n Behoefte aan ’n plaaslike kwantifiseringsmetode is geïdentifiseer. Hierdie studie stel ’n eenvoudige, gebruikersvriendelike kwantifiseringsmetode bekend. Dit word saamgestel uit faktore wat verband hou met die plaaslike omgewing: Uitlaatgasse, Hulpbronuitputting en Rommelvervaardiging. Uiteindelik word ’n saamgestelde waarde, wat die Omgewingsimpak-indeks genoem word, bereken om vergelyking te vergemaklik. Hierdie kwantifiseringsmetode word aan die hand van ’n gedeeltelike lewenssiklus-analise as ’n wiskundige hulpmiddel ontwikkel. Slegs die eerste fase van ’n gebou se lewenssiklus word beskou tydens hierdie studie, maar dit is moontlik om die ander twee fases in te sluit. Die voorgestelde metode het die vermoë om die omgewingsimpak te bereken en ook te optimeer. Tydens die ontwerpsfase, wanneer belangrike besluite geneem moet word, kan so ’n hulpmiddel van enorme waarde wees om die beste opsie uit verskillende alternatiewe te help identifiseer. Die studie beskou twee tipes behuisingseenhede vir die doel van implementering van die kwantifiseringsmetode: die konvensionele baksteen en mortel metode en alternatiewelik ’n ligte staalraamwerk-gebou. Tydens implementering van die voorgestelde metode, demonstreer die model dat dit werk soos dit veronderstel is om te funksioneer. Verder is getoon dat ’n ligte staalraamwerk-gebou ’n waardevolle alternatief is om te ondersoek, maar dit moet liefs met ’n meer akkurate lewenssiklus-analise bevestig word.