Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Sustainability is becoming an increasingly important aspect in all facets of engineering. It is in particular an
important consideration in the structural engineering industry, due to the prominence of the negative impact
this industry has on the environment, both on a national and international scale.
The problem, however, is that sustainability is a mostly unknown and highly debated topic. It is not only
difficult to quantify, but even difficult just to define. In the field of structural engineering it is an especially
difficult task to consider sustainability. It is still a very new field of research and difficult to apply. It is therefore
important that continued research be done in order for there to be a better understanding of how
sustainability should be considered and applied in the context of structures.
In an attempt to assess the environmental impact of building structures, there are two basic approaches that
are followed. The first, the application-oriented method, is a simple, points-based system. The second, the
analysis-oriented method, makes use of detailed indices and factors to quantify the impact. This study aims to
develop an analysis-oriented method, specifically designed for the complete life cycle of buildings in the South
African environment. This is accomplished by continuing the work that was started by Brewis (2011), and
continued by Brits (2012).
Brewis developed the approach for the pre-use phase, while Brits developed the approach for the end-of-life
phase. Both focussed their application on low-cost housing development. However, the approach is defined
for the use of the analysis of a building envelope. The details of developing the environmental life cycle
assessment (LCA), as well as the approaches for the pre-use phase and the end-of life phase are discussed in
Chapter 3.
The study develops the use phase of the proposed environmental life cycle assessment for buildings in Chapter
4. It discusses in detail the two main components of the use phase, namely maintenance and operation. While
maintenance is concerned with the replacement of building materials in the structure, the operation
component is concerned with the energy needs during the use phase.
It is determined that the energy use that is directly related to the building envelope is the energy required for
the space heating and cooling of the building. This is due to the fact that the thermal properties of the building
envelope influence the thermal environment within the building, and thereby impact the use of energy to
regulate that thermal environment.
In order to make the most use of both of these components within the application of the proposed LCA, it was
decided to model a residential building structure that uses consistent energy to regulate the thermal
environment within the structure.
However, it is not only the objective to use the proposed LCA as an assessment tool, but also as a comparative
and optimisation tool. Therefore one component, the external walls, was selected as a variable component.
This component was varied to form a total of nine different buildings. These nine buildings were then used in a
comparative study in order to try to determine an optimum choice of external walling system, based on the
results of the environmental impacts determined in the LCA. It is also used to try to explain exactly how and to
what extent the external walling system contributes to the environmental impact, and what useful application
value we can gain from this knowledge. The results showed that a minor increase in the materials impact (due to attempts to improve the thermal
capacity of the external walls) were in most cases countered by a decrease in the energy impact, which in
seven of the eight alternative external walling systems led to a net decrease in environmental impact (EI)
categories one to four. It was also found that with the increase of the R-value of the external walling systems, the environmental
impact of the building steadily decreased, in terms of four of the five impact categories.
The only exception to these trends was found in the fifth impact category: waste generation. The reason for
this is the fact that energy impact in this environmental impact category is negligible, and therefore does not
contribute much to the net change in environmental impact. / AFRIKAANSE OPSOMMING: Die belangrikheid van volhoubaarheid neem al hoe meer toe in alle aspekte van ingenieurswese. In die
industrie van struktuuringenieurswese is dit van besonderse belang as gevolg van die prominente negatiewe
impak van hierdie industrie op die omgewing, op beide ’n nasionale en internasionale skaal.
Die probleem is egter dat volhoubaarheid nog meestal gesien word as ʼn onderwerp wat onbekend en hoogs
debatteerbaar is. Dit is nie net moeilik om te kwantifiseer nie, maar selfs moeilik om dit net te definieer. In
struktuuringenieurswese is dit veral ʼn moeilike taak om volhoubaarheid in ag te neem. Dit is nog ʼn baie jong
studieveld wat moeilik is om toe te pas. Dit is dus van uiterse belang dat verdere navorsing gedoen word sodat
daar ʼn beter begrip kan wees van hoe volhoubaarheid op die lewensiklus van strukture toegepas kan word.
In 'n poging om die omgewingsimpak van die geboustrukture te evalueer, is daar twee basiese benaderings
wat gevolg kan word. Die eerste, die toepassingsgeoriënteerde metode, is 'n eenvoudige, punte-gebaseerde
stelsel. Die tweede, die analise-georiënteerde metode maak gebruik van gedetailleerde indekse en faktore om
die omgewingsimpak te kwantifiseer. Hierdie studie beoog om 'n analise-georiënteerde metode te ontwikkel,
wat spesifiek ontwerp is vir die analise van die volledige lewensiklus van geboue in die Suid-Afrikaanse
omgewing. Dit word gedoen deur die voortsetting van die werk wat begin is deur Brewis (2011), en voortgesit
is deur Brits (2012).
Brewis het die benadering vir die eerste fase (voor-gebruik) ontwikkel, terwyl Brits die benadering vir die finale
fase (einde-van-lewe) ontwikkel het. Beide het die fokus van hul toepassings geplaas op lae-koste behuising.
Die benaderings is egter gedefinieer vir die algemene analise van ʼn gebou se raamwerk. Die besonderhede van
die ontwikkeling van die omgewingslewensiklus analise (OLA), asook die benaderings vir die eerste en finale
fases, word in Hoofstuk 3 bespreek.
Die studie ontwikkel die gebruiksfase van die voorgestelde omgewingslewensiklus analise vir geboue in
Hoofstuk 4. Dit bespreek die twee hoofkomponente van die gebruiksfase, naamlik die instandhouding en
bedryf. Terwyl instandhouding gemoeid is met die vervanging van boumateriale in die struktuur, is die
bedryfskomponent gemoeid met die energie behoeftes tydens die gebruiksfase.
Dit word bepaal dat die energie verbruik wat ʼn direkte verband het met die gebou se raamwerk, die energie is
wat nodig is vir die verhitting en verkoeling van die gebou. Dit is te danke aan die feit dat die termiese
eienskappe van die gebou se raamwerk die termiese omgewing binne die gebou beïnvloed, en sodoende 'n
impak het op die energie wat benodig word om die temperatuur te reguleer.
In ʼn poging om die spektrum van die voorgestelde OLA ten volle te benut, is dit besluit om die toepassing
daarvan te illustreer op 'n residensiële gebou wat van konsekwente energieverbruik gebruik maak om die
termiese omgewing binne die gebou te reguleer.
Dit is egter nie net die doel om die voorgestelde OLA te gebruik as 'n assesseringsinstrument nie, maar ook om
die OLA se funksie as ’n vergelykende en optimaliseringshulpmiddel te illustreer. Dus is een komponent, die
eksterne mure, gekies as 'n veranderlike komponent. Hierdie komponent is gewissel om 'n totaal van nege
verskillende geboue te vorm. Hierdie nege geboue is gebruik in 'n vergelykende studie in 'n poging om 'n
optimale keuse van eksterne mure te bepaal, gebaseer op die resultate van die omgewingsimpak wat in die
OLA te bepaal is. Dit word ook gebruik om te probeer om te verduidelik presies hoe en tot watter mate die
eksterne mure bydra by tot die omgewingsimpak, en watter nuttige toepassingswaarde geput kan word uit
hierdie kennis.
Die resultate het getoon dat 'n toename in die materiaal impak (weens pogings om die termiese kapasiteit van
die eksterne mure te verbeter) in die meeste gevalle teengewerk is deur 'n afname in die energie impak. In sewe van die agt alternatiewe eksterne muurstelsels het dit gelei tot 'n netto afname in omgewingsimpak vir
kategorieë een tot vier.
Dit is ook gevind dat die omgewingsimpak van die gebou stelselmatig gedaal het met die toename van die Rwaarde
van die eksterne muurstelsels, ook in terme van kategorieë een tot vier.
Die enigste uitsondering op hierdie tendense is gevind in die vyfde impak kategorie: die afval wat gegenereer
word. Die feit dat die effek van energie verbruik gering is in hierdie omgewingsimpak kategorie, lei tot die feit
dat dit nie veel bydra tot die netto verandering in die omgewingsimpak nie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/96923 |
| Date | 03 1900 |
| Creators | Van Noordwyk, Arina |
| Contributors | De Villiers, Wibke I., Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 173 pages : illustrations |
| Rights | Stellenbosch University |
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