Designing Sustainable Structures

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Designing Sustainable Structures

  1. 1. Designing Sustainable Structures Tim McMinn 03 December 2009
  2. 2. Environmentally Sustainable Design <ul><li>Climate Change </li></ul><ul><li>Water shortages </li></ul><ul><li>Limited resource depletion </li></ul><ul><li>Excessive waste disposal </li></ul>ESD Seeks to Address
  3. 3. Environmentally Sustainable Design <ul><li>The critical component of ESD is achieving resource efficiency </li></ul><ul><ul><li>Services </li></ul></ul><ul><ul><li>Solar shading and building orientation </li></ul></ul><ul><li>Daylight penetration for improved internal environments </li></ul><ul><li>Water capture and reuse </li></ul><ul><li>Reducing material use - this is an area of building design which structural engineers can influence </li></ul>
  4. 4. Structural Sustainability <ul><li>Building construction consumes: </li></ul><ul><ul><li>32% of global resources </li></ul></ul><ul><ul><li>12% of fresh water in OECD countries </li></ul></ul><ul><li>18% of Australian waste going to landfill is from construction and demolition </li></ul>Green Building Council of Australia and Australian Bureau of Statistics Figures
  5. 5. Structural Sustainability <ul><li>Concrete </li></ul><ul><ul><li>Focus of presentation </li></ul></ul><ul><ul><li>CO 2 emissions associated with concrete </li></ul></ul><ul><ul><li>Cement substitution </li></ul></ul><ul><ul><li>Techniques to reduce volume </li></ul></ul><ul><li>Steel </li></ul><ul><li>Timber </li></ul><ul><li>Design for deconstruction </li></ul><ul><li>Building reuse </li></ul><ul><li>Focus on design efficiency </li></ul><ul><li>Structures and ESD Rating Tools </li></ul>
  6. 6. Concrete and Emissions <ul><li>Concrete is one of the most widely used artificial products </li></ul><ul><li>5-8% of total greenhouse emissions come from cement production </li></ul><ul><li>Cement production accounts for around 90% of emissions associated with concrete </li></ul>
  7. 7. Cement Production <ul><li>Cement is made by heating limestone to over 1300 o C </li></ul><ul><li>CaCO 3 ―› CaO + CO 2 </li></ul><ul><li>Around 0.9 tonnes of CO 2 produced for every tonne of cement </li></ul><ul><li>Around half is due to calcination process </li></ul>Zeobond 2008
  8. 8. Cement Substitution <ul><li>Proportion of cement can be reduced with cement substitutes </li></ul><ul><ul><li>Fly-ash </li></ul></ul><ul><ul><li>Blast-furnace slag </li></ul></ul><ul><li>Collie fly-ash </li></ul><ul><ul><li>Until recently, has been of poor quality </li></ul></ul><ul><ul><li>Benefits: </li></ul></ul><ul><ul><ul><li>Reduces water requirements </li></ul></ul></ul><ul><ul><ul><li>20-60% emissions reduction </li></ul></ul></ul><ul><ul><ul><li>Up to 180kg CO 2 /m 3 reduction on 40MPa concrete with GP cement </li></ul></ul></ul><ul><li>Geopolymer concrete </li></ul><ul><ul><li>Low grade, developmental </li></ul></ul>
  9. 9. New Technologies to Reduce Volume <ul><li>Cement makes up around 11% of the volume of concrete </li></ul><ul><li>40-50% concrete reduction has equivalent load carrying capacity </li></ul><ul><li>59 Albany Highway: </li></ul><ul><ul><li>7 storey commercial building in Victoria Park </li></ul></ul><ul><ul><li>Precast/bubbledeck system used </li></ul></ul><ul><ul><li>1138.6 tonnes of CO 2 saved </li></ul></ul><ul><li>Fairlanes </li></ul><ul><ul><li>27 storey mixed-use building in East Perth </li></ul></ul>Bubbledeck
  10. 10. Steel & Timber <ul><li>Steel </li></ul><ul><ul><li>Most steel is scrapped and recycled at the end of an elements life </li></ul></ul><ul><ul><li>Major disadvantage is embodied energy </li></ul></ul><ul><li>Timber </li></ul><ul><ul><li>Potential to be a truly renewable source of material </li></ul></ul><ul><ul><li>Stores carbon </li></ul></ul><ul><ul><li>Many options for reuse/recycling </li></ul></ul><ul><ul><li>Attempt to source material from local, sustainable plantations (AFS or FSC) </li></ul></ul><ul><ul><li>Issues with Green Star – only FSC is recognised </li></ul></ul><ul><li>Both materials can be reused, unlike concrete </li></ul>
  11. 11. Designing for Deconstruction <ul><li>5.85 million tonnes of C&D waste are sent to landfill each year </li></ul><ul><li>DfD facilitates material reuse by “non-destructive” demolition </li></ul><ul><li>Reusing elements is more efficient than recycling </li></ul><ul><li>Details of deconstruction procedure need to be incorporated into drawings, and a deconstruction plan </li></ul><ul><li>Masonry, timber, and steel all lend themselves to this approach </li></ul>
  12. 12. Big Dig House Single Speed Design Architects Lexington, Massachusetts, USA Sustainable Environments, 2008
  13. 13. Building Reuse <ul><li>Embodied energy accounts for 8-10% of building emissions </li></ul><ul><li>Building re-use is the simplest way to reduce embodied energy </li></ul><ul><li>Most efficient use of materials: </li></ul><ul><ul><li>No transport </li></ul></ul><ul><ul><li>No reprocessing </li></ul></ul><ul><li>Challenges include: </li></ul><ul><ul><li>C hanges of use </li></ul></ul><ul><ul><li>Strengthening work </li></ul></ul>
  14. 14. Structures & ESD Rating Tools <ul><li>Green Star </li></ul><ul><li>Rating tools focus heavily on energy efficiency </li></ul><ul><li>On projects which aim for high ratings, structural points can become very important </li></ul><ul><li>Focus on embodied energy </li></ul><ul><ul><li>Building reuse has high priority </li></ul></ul><ul><ul><li>Cement substitution </li></ul></ul><ul><ul><li>Recycled Steel </li></ul></ul><ul><ul><li>Sustainable Timber </li></ul></ul><ul><ul><li>Design for Deconstruction. </li></ul></ul>

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