The Sydney Opera House
Instructions:
For this assignment, students are required to:
– Select one of the nine projects nominated by the International Union of Architects as significant Twentieth Century Australian Architecture (http://www.architecture.com.au/architecture/national/notable-buildings)
– Identify a building material that has been used in at least 1% of the overall building area, or at least 0.5% of the overall building volume.
– Specify an alternative material that could have been used in achieving similar function in the building
– Discuss the advantages and disadvantages in both materials in the building of interest
– Evaluate and compare the embodied energy of both materials
ADDITIONAL GUIDANCE :
It is your responsibility to select only ONE of the nine buildings (SYDNEY OPERA HOUSE). Information regarding the history of the building is NOT essential. It is however important to state the building material of choice ( CERAMIC ROOF TILES WITH COLORBOND METAL SHEET ROOFING AS ALTERNATIVE), and the building element where it is used, For instance; Timber used in roofing in the National Parliament House; concrete used in the foundation at the Sydney Opera theatre etc. It will also be important to state the size of the building material of interest. It is not advisable to engage in measurement and estimating of building materials. A figurative estimate, preferably based on the literature will suffice.
It is also important to select a part of the building that is amenable to having an alternative. It can be argued that structural design will be the more convincing basis to select alternative materials for load-bearing structures. Hence, it is advisable to focus more on non-load bearing elements of buildings, so that choices can be sufficiently based on the mechanical, thermal, and acoustic considerations.
In selecting alternatives, it is worth mentioning that – suggesting laminated glass in place of toughened glass may not be acceptable (because they are both glass) except there is justification for such. It will therefore be important to focus on selection of materials with clear differences in material configuration; for instance, Copper may be used in place of Zinc, Timber may be used in place of Steel; Aluminium may be used in place of Stainless Steel etc.
Lastly, it may help to highlight relevant case studies where the chosen alternative material have been used to achieve similar purpose. Although this may be subjective, it will avoid making selections that are rather impractical. The lack of a relevant case study will however not diminish the quality of the work inasmuch as concerted attention is given to the relevant building properties. Where appropriate, it may be useful to include pictures and diagrams, but cross reference them and demonstrate in the text that you understand their relevance.
Solution.
The Sydney Opera House
Background
The structural design of the Sydney Opera House is an excellent and complex architectural design. The SOH covers approximately 11 acres of floor space (380 ft wide and 611 ft long) and, therefore, requires immense structural materials for the development of a credible and durable building. The expansiveness of the building required an equally large and complex roof design. According to the CBS (2013), the roofing is complex and its vaults stretch up to 221 feet. The complexity of the design and roof required the utilization of an efficient plan and materials. The shell roof weighs 27,230 tons and used 2,194 pre-cast sections of concrete, each making up to 15 tons (Wells, 2013). Additionally, 1,056,056 Swedish ceramic tiles integrated into 4,253 pre-cast lids covered the roof contributing greatly to the total weight of the building (161,000 tons) (CBS, 2013). Further, a part of the roof mouths and other building areas used French glass covering 67,000 square feet (Porter, 2013). This project offers an analysis of the main material (Swedish ceramic tiles) used in the SOH roofing by outlining and discussing its properties and suitability in the building. Additionally, it proposes and discusses the suitability and properties of Colorbond metal sheet as an alternative material for use in constructing the roof.
The preference of Swedish ceramic tiles for the roofing of SOH was influenced by the numerous properties of the material. The designers considered the durability of the ceramic tiles, strength, and cost-effectiveness before their application in developing the roof. Some of the physical and chemical properties considered in determining whether to use ceramic tiles included its low density in comparison to metals, high decomposition temperature, its hardness and brittleness, strength, toughness, thermal conductivity, resistance to thermal shock and corrosion, and its electrical resistivity among others (Srikari, 2016). The choice was made by determining its applicability in design such a large roof in comparison with other materials. The comparison of the properties of the material with those of Colorbond metal sheets when applied for constructing the roof enhances understanding of construction materials and applicability. The comparison determines the embodied energy of both materials and discusses the advantages and disadvantages by placing emphasis on the aesthetic look, impact on the environment, cost-effectiveness, strength and durability among other properties.
The possible alternative to the ceramic tiles, Colorbond’s steel sheets, offer numerous properties that make them applicable in roofing of a building of SOH’s significance. The material is strong and secure for building and comes in different colors giving an aesthetic value. Additionally, the material’s solar reflective ability, depending on the color of the sheets enhances thermal efficiency and promote sustainability (Colorbond, 2017). The Sydney Opera House uses white tile enhancing the reflectance ability. Further, though not as durable as the ceramics, the sheets offer significant durability, strength, and cost-effectiveness. The application of the materials would cut down the costs used for the construction and address the significant challenge of the building’s weight. The density, melting point, hardness and strength, toughness, and electrical resistivity and thermal conductivity among other mechanical properties compare significantly to the ceramic tiles used in the building. The advantages and disadvantages of the two materials show the different factors that influence the selection of building materials.
The Swedish Ceramic Roof Tiles
Ceramic tiles have numerous advantages and disadvantages depending on the application and building requirements. The consideration of the properties is critical before selecting the material. The Sydney Opera House roofing was done using the Swedish ceramic tiles. These tiles were chosen following an analysis of their physical, mechanical, and chemical properties. One of the major the significant advantages of the ceramic roofing is their higher reflective property and the ability to emit heat easily. Applying ceramic tiles in roofing ensures a high reflection of sun rays and emission of heat thus limiting absorption and keeping the building cooler. The high solar reflectance and thermal emittance of the ceramics classify roofs constructed using the material as cool roofs (ABC, 2017). The SOH roof is a ceramic roof, which has high reflectance and thermal emittance. This qualifies it as a cool roof. The roof enhances cost-effectiveness and promotes energy efficiency by minimizing the use of air conditioners. The utilization of ceramic tiles, which promote cool roofing, serves a critical role in enhancing ecological sustainability, cost-effectiveness, and supporting the efficiency of air conditioning systems.
The Swedish ceramic roof tiles are attractive and offer high performance. The attractiveness of a building is greatly affected by the roofing and the material used in the most conspicuous parts of the building. As a performing arts center, the attractiveness of the design and final appearance was one of the major considerations made before the commencement of the Sydney Opera House project. The roofing contributes greatly to the aesthetic value of the building. The use of ceramic tiles makes the building more attractive. These tiles come in different designs and colors making them one of the most conspicuous and roofing materials. The consideration of the aesthetics and their performance as a roofing material made the Swedish roofing tiles the best choice for application in building the roof. The ceramic tiles not only make the building attractive but also give it durability and high functionality (CBS, 2013).
Ceramics have certain chemical properties that support their suitability as the roofing material for the Sydney Opera House. The materials have a high corrosion resistance due to the inertness of ceramic materials, which offers a significant chemical resistance to acids and bases. Following that a major issue considered before the choice of a roofing material is the ability to resist weak acids, this property makes ceramic roofing a viable and suitable material. The ability of the material to resist the effects of weak acids and bases makes the roofing material essential for the construction of the SOH (Thompson & Bayne, 2015). The extensive use of the ceramic tiles in the House’s roof makes certain that acid rain does not corrode the roof. Rain water contains weak acids whose concentration depends on the area. Since ceramics do not react with weak acids or bases, the application of the material translates to improved durability. Even when very strong acids may corrode the tiles, the impossibility of such rains or high amount of acid makes the roofing material important.
The mechanical properties of ceramic roofing tiles make them applicable for construction. Ceramics have a high rigidity and brittleness and a high elastic modulus. The combination of these properties makes the material a critical roofing material. However, the properties are determined by the temperatures used in the manufacturing and the crystallinity content. A high crystallinity and low temperatures in the processing allows the production of ceramic tiles that have a higher elasticity modulus and increased brittleness (Thompson & Bayne, 2015). The SOH used more than a million tiles in developing the roof. Considering the amount of these tiles, it was possible to request the customization of the tiles to meet the required rigidity and brittleness standards. These properties make the Swedish ceramic tiles the most applicable material in the construction of the roof.
The Swedish ceramic roof tiles have a high melting point, a higher temperature wear resistance, and a considerably high thermal resistance. These properties make the material highly applicable in areas that record high temperatures. Though the melting point does not have a direct influence on the building, it plays an essential role in the manufacturing process (Thompson & Bayne, 2015). The thermal resistance and a high temperature wear resistance are critical for ensuring that exposure of the material to high temperatures does not result in fast wearing or inefficiency. The roof of the SOH is exposed to sunlight and, therefore, requires the application of a material able to resist thermal wearing.
The greatest challenges of installing ceramic roof tiles in big projects such as the Sydney Opera House include high capital input, time-consuming and labor-intensive installation process, brittleness and low toughness (Thompson & Bayne, 2015). The SOH, for instance, required more than a million tiles, whose cost was considerably high. The cost affected the cost-effectiveness of the whole project. The installation process required significant labor and time, which also contribute towards the element of cost-effectiveness. Further, the major mechanical and physical disadvantages include the brittleness and low toughness, which make handling difficult (Thompson & Bayne, 2015). The Opera House shells are a complex design, therefore, handling more than a million pieces of the brittle and low toughness material must have posed a great challenge.
Colorbond Metal Sheet Roofing as an Alternative
Colorbond produces steel sheets of different designs and colors that would be applicable in the construction of the Sydney Opera House roof. The use of the sheets in the construction would be a nearly effective alternative as the Swedish ceramic tiles. One of the major advantages of the steel sheets is their heat reflectance. Colorbond produces sheets of different colors, which have high reflectivity and thermal emittance. For instance, white sheets have a high reflectivity and reduce heating thus keeping the building cooler (Colorbond, 2017). However, compared to the ceramic tiles, the sheets have a higher thermal conductivity and a lower emittance. These influence its applicability negatively especially in the construction of large, multipurpose and comprehensive designs.
The use of the steel sheets would be more cost-effective as compared to using the tiles. Colorbond sheets are produced in Sydney, unlike the Swedish ceramic tiles which were manufactured in Sweden and shipped to Sydney. Using the steel sheets would cut down on costs significantly. However, the ceramic tiles have a higher durability compared to the sheets and, therefore, sheets would be costly in the long-term. Most importantly, the thermal efficiency of the steel sheets caused by the high reflectance and low thermal conductivity would reduce the cooling bill and promote energy efficiency (Colorbond, 2017). These advantages would make using the sheets in the roofing beneficial both regarding cost-effectiveness and environmental/ecological sustainability.
Additionally, metal sheets offer longevity and durability. Although not as durable as ceramic tiles, proper installation of metal sheets in roofing offers between 20 and 50 years of performance life. Using metal sheets, especially steel, copper, or zinc-alloyed sheets, offers the longevity and durability. The application of the material in the development of the Sydney Opera House would have given the building this durability. The State Library of Victoria building has a metal sheet roof. Since its completion in 1912, the building was first re-sheeted in 1959, offering more than 45 years of service (Vorbach, 2013). This shows the high durability of metal sheets. The copper sheets used at the time had started wearing off, and parts would often get blown by heavy winds and storms. This shows that the durability of metal sheets is lower compared to that of the ceramic roofing tiles (Acton, 2013).
Installation of metal sheets is simpler compared to the installation of ceramic tiles. The tiles have several times more weight per square meters as compared to metal sheets. The process would be less tedious and would require less labor and time (Allen & Iano, 2013). This would contribute considerably towards cost-effectiveness. Moreover, shaping metal sheets to fit different designs would be simpler as compared to shaping ceramic tiles which are brittle. The brittle nature of ceramics leads to wastage as many tiles break, unlike metal sheets that are unlikely to get damaged in the process of fixing the roof.
Despite the advantages, roofing using metal sheets offers various disadvantages. These include its lower corrosion resistance, high thermal conductivity, and less heat emission. Using the material in the building the SOH’s roof would pose a challenge of fast wearing from high temperatures and corrosion caused by acid rain. Metals react with acids and corrode in the process (Acton, 2013). Even though steel does not corrode as fast as iron, it is less efficient as compared to ceramic roofing tiles. Moreover, the high thermal conductivity and less heat emission would create high temperatures in the building requiring an efficient air conditioning system. However, using metal sheets coated with high reflective materials can curb this concern and function even better than ceramic tiles.
Embodied Energy of the Materials
Ceramic roofing tiles and the steel sheets require significant energy for production. Embodied energy is the amount of energy required for manufacturing a building material from the processes of retrieving raw materials and refining to the different stages of processing. The embodied energy is calculated by determining the energy required to retrieve, transport, process, and produce the final product (Binggeli, 2011). The main types of transport include air, road/diesel, rail/diesel, rail/electric, and sea transportation. These transportation modes consume energy as shown in the table.
| Type of Transport | MJ/ton per Km |
| Air | 33 – 36 |
| Road/diesel | 0.8 – 2.2 |
| Rail/diesel | 0.6 – 0.9 |
| rail/electric | 0.2 – 0.4 |
| Sea | 0.3 – 0.9 |
Further, the
combustion value of the raw materials, the machinery applied in the extraction
of raw materials and the manufacturing process among other elements of the
production affect the embodied energy. Binggeli
(2011) asserts that ceramic tiles have a high embodied energy. The white
ceramic tiles used for roofing the building were manufactured in Sweden by Höganäs. The extraction of the raw materials, processing, drying and
transportation of the end product from Sweden to Sydney contributed to the
significantly high embodied energy. On the other hand, Colorbond metal sheets
are produced in Sydney with raw materials from within the country. This cuts
down costs of production significantly. However, the means of transport used
for the two materials may make a difference in embodied energy of the material.
Bibliography
ABC, 2017. What is Cool
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Available at: http://www.architecture.com.au/architecture/national/notable-buildings
Allen, E. & Iano, J., 2013. Fundamentals of building construction : materials and methods. Hoboken : Wiley.
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Available at: http://164.100.133.129:81/eCONTENT/Uploads/Session-13-Ceramics%20and%20PM.pdf
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Available at: http://www-personal.umich.edu/~sbayne/dental-materials/022-Ceramics-Prop1/022-Handouts/22-Ceram-Prop1-Notes-CL.pdf
Vorbach, N., 2013. Rejuvenating the roof. [Online]
Available at: http://exhibitions.slv.vic.gov.au/dome100/100-dome-stories/uncovering-dome/rejuvenating-roof
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Available at: http://www.australia.gov.au/about-australia/australian-story/sydney-opera-house