Doctoral Degrees (Forest and Wood Science)

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Browsing Doctoral Degrees (Forest and Wood Science) by Author "Crafford, Philippus Lodewicus"

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    An investigation into the environmental sustainability of buildings in South Africa with a focus on timber building systems
    (Stellenbosch : Stellenbosch University, 2019-04) Crafford, Philippus Lodewicus; Wessels, C. B.; Stellenbosch University. Faculty of Agrisciences. Dept. of Forest and Wood Science.
    ENGLISH ABSTRACT: Buildings are responsible for about 33% of global anthropogenic carbon dioxide emissions, high-energy consumption and other environmental resource uses. Numerous studies over the past 20 years showed that wood-based constructions have lower environmental impacts in terms of energy use, global warming potential, air pollution, water pollution and solid waste production than steel and cement-based systems. However, there are still questions about the accuracy of green building rating tools. The objectives of this research were to (1)critically examine established international green building rating tools and methods to measureenvironmental impacts of buildings, (2)to investigate and quantify the environmental impact of selected building systems, components,and processes (including transport) relevant to the South African context, and (3)to develop a local environmental impact base and comparison models for timber-based buildingand future resource demand in South Africa. A review of green building rating tools indicated that the well documented environmental benefits of using wood was not sufficiently reflected in these rating systems. Life cycle-assessment is recognized as the best way to holistically evaluate the environmental impacts of a building. However, there is a critical need for local life cycle assessment based research in South Africa and other developing countries on building products and processes. At present, more than 70% of all sawn timber in South Africa is used in buildings, mainly in roof structures. A comparison between several roof truss systems (South African pine, Biligom and light gauge steel) using the life cycle assessment method showed that the two timber systems had overall the lowest environmental impact. Although the difference between the timber systems was small, light gauge steel had a 40% higher normalised impact over all assessed environmental impact categories. In a modelling analyses where different future building market scenarios in South Africa were compared, it was shown that if wood based residential buildings increase its market share to 20%, the embodied energy and global warming potential of the sector decrease by 4.9% from the current levels. If all new constructions is wood based, the total embodied energy and global warming potential of the residential building sector will decrease by 30.4%. It was shown that with the use of wood resources currently exported as chips, as well as planting trees in areas that have been earmarked for afforestation, it will be possible (in the long term) to sustain a future residential building market where all constructions are wood based. A decision support tool was developed to compare the environmental impact of timber transport in and to South Africa. Transport linked to local and international timber sources and markets were modelled for global warming potential and primary energy impacts. It was shown that the Johannesburg, Nelspruit and Durban markets were well located within current local truck networks and showed lower global warming potential (GWP) values per ton kilometre compared to Cape Town and Port Elizabeth markets. Results also illustrated that importing timber from regions such as Cacador, Brazil to the Cape Town and Port Elizabeth areas using container shipping will have a lower global warming potential impact than using timber from the Nelspruit area with truck transport.