Development of a sustainability index for South African dwellings incorporating green roofs, rainwater harvesting and greywater re-use

[摘要] ENGLISH ABSTRACT: South African water service providers experience major problems with providing adequate waterservices to consumers. Water service providers in South African urban areas rely on traditionalcentralised infrastructure, such as bulk supply networks, to provide water services. Alternativesupply and stormwater drainage methods should be encouraged to help mitigate these problems.The researcher thus aims to quantify the potential impact that three alternative methods may haveon a given dwelling in terms of its dependence on traditional bulk water services. The threealternatives considered in this thesis are the construction of green roofs, rainwater harvesting andgreywater re-use.An efficiency of dwelling water use index (EDWI) was developed during this research project. Itwas designed in such a way as to show what portion of municipal water services could bereplaced within the given dwelling by using the proposed techniques. The final EDWI-rating isobtained by using the EDWI-software tool developed as a part of this research. The derivedEDWI-rating ranges from 0 to 100, with a rating of 100 indicating a dwelling requiring only theremoval of a portion of sewage by a municipality, but no external water supply. Such a dwellingwould also not require any water from a municipal network to meet domestic demand and allstormwater from its roof would be utilised within the plot boundaries. Results presented in thisthesis illustrate how different geographical regions require different system specifications toobtain optimal EDWI-ratings, thereby lowering their dependence on the respective municipalwater services.Validation of the EDWI-system proved difficult as no similar index could be found during theliterature review. It was therefore decided to benchmark the EDWI-system using three modeldwellings with nine configurations producing a total of 27 analyses. The EDWI-system providesa conceptual foundation for sustainable water services to South African households in servicedurban areas. Future work could further improve the EDWI-system by testing its practicalapplication so that it may be extended to act as a national barometer, used to comparedecentralised water services in terms of sustainability.

[发布机构] Stellenbosch University