Zero Carbon Isn’t Really Zero: Why Embodied Carbon in Materials Can’t Be Ignored


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A Design Intelligence webinar provided by Arup consultants focusing on environmentally sustainable building design. The webinar is based on a web article authored by Frances Yang and Engin Ayaz.

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  • DI to introduce themselves and other speakers
  • Now that you know who we are, we’d like to know you
  • More detailed agenda outline. Can follow the bars at the upper right as we progress through the talk. Ask them to type in questions if the function is available.
  • (Frances)In talking about zero carbon, we need to first set out some definitions. We have adopted the use of the term “carbon” as abbreviation for carbon dioxide equivalent, the metric for global warming potential.In buildings, there are two primary types of carbon emissions. Most people are familiar with those related to the operations of the building. That is, from running the building – the heating, lighting, cooling, so forth. We term this operational carbon and it is shown here at the lavendar line.Now if you consider the building as a product and include everything that goes into and out of it over its lifecycle, there is another source of carbon that has to do with the materials that make up the building assembly. From extraction, to manufacture and transportation, to design and construction, refurbishments and maintenance, to whatever happens at the end of its life: renov, demo, recycling and/or reuse of its components. Counting this quote-unquote “embodied carbon”, as represented by the red line, in addition to the operational carbon, gives us a more complete accounting of the carbon emissions of a building over its lifecycle.
  • (Frances) So now that we are clear on what we mean by embodied carbon, is would interesting to know where all the carbon comes from. This graph from the WRI shows a breakdown of sources of GHGs by industry subsector. You can see that huge portions are from materials cement, iron & steel – the materials that go into our buildings.
  • Finally, another way of setting energy and carbon in context, is shown in this chart.The horizontal axis represents what is being measured and the vertical represents the scope, still as related to buildings. As we go from lower left to upper right, we increase in comprehensiveness in accounting for environmental impacts, but also complexity.So the simplest metric here is energy. Another level up in calculations would be CO2, the by-product currently of most concern in our energy production because it is the main contributor to greenhouse gases. Then CO2e, short for “carbon equivalents”. This takes into account the other GHG, like methane and nitrous oxide. Still higher levels up are metrics that consider other environmental impacts, like toxicity, resource depletion, waste generation, to name a few.Now on the vertical axis, the smallest in scope is within operational electricity and gas consumption. Again, this is the energy to run the building. Next would come embodied and transport, mostly of building occupants. Waste and Water are rarely tracked in their energy demand and carbon emissions, but do have their own environmental impacts.The increase in complexity is an indicator of why up to recently, people only really tried to measure operational energy.
  • (Frances)Here we show the scope of our study. Using carbon as the metric instead of energy is advantageous, b/c the literacy regarding carbon has increased tremendously in recent years. Al Gore brought worldwide attention to atmospheric CO2 levels. About the same time, California passed an assembly bill (AB32) that warrants 80% reduction of US greenhouse gas emissions by 2050 when compared with 1990 baseline. Conducting a comparative analysis in “carbon” units thus allows us to relate to these macro-scale goals and address a wide audience.Meanwhile, when chose to limit our study on embodied and operational demands because this is where we in the Arch, Engring and Construction industry can have the greatest influence.
  • (Frances)Again we delineate between embodied and operational carbon.Hopefully we’ve clarified now the terms around “zero carbon”While we have emphasized the difference btwn embodied and operational carbon, the next natural question that comes up is, how do they compare?
  • (Frances)Well, in performing a Literature Review, we have found a few studies containing some breakdowns of embodied and operational carbon, more often embodied versus operational energy. As summary of the ones most often cited and done in the US, Canada, or UK, is shown here.Without getting too caught up in the details, there are a couple themes to draw from here. One is that there is variability in the numbers both across studies and within them. Sometimes it is due to region, but mostly it is due to methodology. All the authors conveyed their results as a range to impart how sensitive the percentage of embodied to operational is to a host of variables -- like lifespan of the building and the types of materials used, as mentioned -- but also how the embodied energy and carbon emissions related to each of the materials were themselves derived. Another theme that we see is a trend in increasing proportions of embodied energy and carbon out of targets to decrease operational demands. This created an interest amongst us to see where new trends in limiting carbon emissions will take us, which is what prompted the series of case studies Engin will now describe...Mark Webster estimates GWP of 2-22% attributable to embodied, based on 3 different building types, over 50 year life, in the US and in Montreal. The lower value represents a wood-framed building in the US and the higher represents a concrete-framed high efficiency building in Montreal. [“Relevance of Structural Engineers to Sustainable Design of Buildings”, Structural Engineering International, March 2004.]Probably the most Cole and Kernan studied office buildings found that about 4-9% of 60 yr life-cycle energy demand is embodied energy [in USGBC presentation, Feb 2007.]Athena estimated 9-12% of 60 yr life-cycle energy demand is embodied energy [in USGBC presentation, Feb 2007.]BuildCarbonNeutral stated eCO2 is 13-18% over 66 yr life [in USGBC presentation, Feb 2007.]In the UK, Eaton and Amato found a much larger percentage of the total carbon emissions attributable to what the materials embodied.Smith and Fieldson of Simon Group (UK) estimate up to 80% [as published in “Whole Life Carbon Footprinting”, The Structural Engineer, March 2008.]
  • (Engin)Can bring up interactive Excel spreadsheet?
  • (Fiona)Future flexibilityHigh performance designDesign for DeconstructionInfrastructureSitingWhile the Case 1 scenario, like many comparisons, assumes a building life of around 60 years, the lifespan of a building in fact varies widely between 20 and 80 years. Demolition has historically been mostly dictated by change of use imposed on an inadaptable building (Minnesota, 2004), not by energy efficiency targets. Joining these two ideas together, a strong rationale emerges for designing for adaptability and ensuring financial incentives to refurbish existing buildings instead of demolishing them.Besides inadaptability, natural hazards such as fire, flood, earthquakes, and hurricanes also threaten building lifespan. In fact, traditional design to code-prescribed hazard levels only assures no loss of life. Building codes do nothing to prevent loss of the material and monetary investment embodied in buildings. The rebuild effort involved can also be represented by Case 4b, urging us to design for more resilient buildings. Performance-based design and utilization of protective systems offer advancements above conventional code-prescribed construction, which can lead to solutions that do not necessarily increase embodied carbon. Even if some solutions to durability strategies -- such as structural redundancy for earthquake resilience -- increase the total embodied carbon in the building, they will likely avoid rebuild and reduce embodied carbon overall.Durability and embodied energyYou can “get more use” out of the initial energy investment, but durable materials tend to have an associated high embodied energyStrength v. sustainability, eg. non-recyclable composites, glass, and coatingsStiffness v sustainability, eg. 90%+ use of crushed concrete aggregate requires about 20% more depthDurability v sustainability, eg. weatherproofing coatings and admixturesEmbodied vs OperationalIt may take greater embodied energy and initial cost to reduce operational energy and costs, particularly for facades.Short-term vs. long-term sustainabilityeg. laminates in recycled content engineered lumber make it unrecyclable (but can reuse!)
  • Fiona or DI to field questions
  • Zero Carbon Isn’t Really Zero: Why Embodied Carbon in Materials Can’t Be Ignored

    1. 1. Zero Carbon Isn’t Really Zero[ Why Embodied Carbon in Materials Can’t Be Ignored ]<br />Total Embodied vs. Operational Carbon for 60 year building lifecycle<br />2: Efficiency<br />3: Clean Power<br />1: Baseline<br />4a: Refurb<br />4b: Rebuild<br />Webinar: Tuesday, Nov 10 2009, 1pm ET / 10am PT<br />
    2. 2. Presenters<br />
    3. 3. AttendeePollfor the Design Intelligence/ Arup conference about “Embodied Carbon in Buildings.”Based on actual attendance dataLocations and professions are approximatedData: Stephanie WhittakerGraphics: Engin Ayaz<br />London<br />Hawaii<br />LOCATIONS<br />Sydney, Aus<br />PROFESSIONS<br />SUMMARY<br />80 people registered<br />57 people attended<br />17Arup people registered<br />10 Arup people attended<br />architect / designer<br />researcher<br />contractor<br />unknown<br />facilities manager<br />engineer<br />
    4. 4. Background of Arup<br />10,000 Staff in 92 Offices<br />global | integrated | employee-owned | multidisciplinary<br />
    5. 5. Principal Fields of Activity in the US<br />Structural Engineering<br />Mechanical Engineering<br />Electrical Engineering<br />Plumbing Engineering<br />Fire Engineering + Life Safety<br />Sustainability<br />Civil Engineering<br />Façade Engineering<br />Energy<br />Infrastructure Planning<br />Transportation Planning<br />Traffic Engineering<br />Communications / IT Consulting<br />Acoustics / Vibration Consulting<br />Audiovisual Consulting<br />Master Planning<br />Security / Risk Assessment<br />Building Energy Assessment<br />Computational Fluid Dynamics<br />Environmental Consulting<br />
    6. 6. Agenda<br />
    7. 7. ARUP SUSTAINABLE BUILDINGS <br />DESIGN FRAMEWORK<br />On every project we aim to help our clients imagine how their buildings might be:<br />© Arup<br />© Arup<br />© Arup<br />© Arup<br />© Arup<br />© Arup<br />
    8. 8. A closer look at life-cycle thinking<br />Renovation, Demolition, Recycling & Reuse<br />Operations & Maintenance<br />Extraction<br />Design & Construction<br />Manufacturing & Transport<br />OPERATIONAL<br /> EMBODIED<br />
    9. 9. Definitions<br />f (Material Energy, Lifespan, Refurbishment)<br />Building Embodied Energy<br />=<br />f (Material Energy, Lifespan, Refurbishment + Energy Source + Chemical Processes + Transport Fuel Type)<br />=<br />Building Embodied CO2<br /><br /><br /><br />
    10. 10. Global Statistics<br />
    11. 11. Zero Energy / Carbon Definition<br />Boundary for <br />Environmental Footprinting<br />Water<br /> increasing<br />comprehensiveness<br />Waste<br />increasing complexity<br />Transport (People & Logistics)<br />Embodied in materials<br />throughout lifecycle<br />Operational Electricity & Gas Consumption<br />Impacts<br />© Arup<br />Energy<br />CO2<br />CO2e<br />(All GHGs)<br />Other <br />Environmental<br />
    12. 12. Zero Energy / Carbon Definition<br />Boundary for <br />Environmental Footprinting<br />Water<br />Waste<br />Transport (People & Logistics)<br />Our <br />Study<br />Embodied in materials<br />throughout lifecycle<br />Operational Electricity & Gas Consumption<br />Impacts<br />© Arup<br />Energy<br />CO2<br />CO2e<br />(All GHGs)<br />Other <br />Environmental<br />
    13. 13. Zero Energy / Carbon Definition<br />Boundary for <br />Environmental Footprinting<br />Water<br />Waste<br />Transport (People & Logistics)<br />Emb<br />Embodied in materials<br />throughout lifecycle<br />Op<br />Operational Electricity & Gas Consumption<br />Impacts<br />© Arup<br />Energy<br />CO2<br />CO2e<br />(All GHGs)<br />Other <br />Environmental<br />
    14. 14. Past Studies<br />Embodied energy is 2-22% of 50 yr life-cycle energy demand<br />Embodied energy is 4-9% of 50 yr life-cycle energy<br />Embodied energy is 9-12% of 60 yr life-cycle energy demand <br />Embodied carbon is 13-18% of 66 yr life-cycle carbon emissions<br />Embodied carbon is 37-43% of 60 yr life-cycle carbon emissions<br />Up to 80% of the life-cycle carbon emissions is embodied carbon<br />
    15. 15. Case Study<br />Color Legend: Embodied vs. Operational<br />Line chart:<br />To compare whole-life carbon emissions trends across 60 year lifecycle<br />for baseline<br />© Arup<br />Doughnut chart: <br />To compare the aggregated carbon emissions at the end of 60 years<br />2: Efficiency<br />3: Clean Power<br />1: Baseline<br />4a: Refurb<br />4b: Rebuild<br />
    16. 16. The tool behind it<br />“EVOCE: Embodied vs Operational Carbon Emissions” Tool, developed by Arup<br />
    17. 17. Case 1: Baseline <br />for baseline<br /> Typical mid-rise office bldg, 60 year lifespan, ASHRAE 2004 baseline<br />
    18. 18. Case 2: Energy Efficiency<br />for baseline<br />Source: CPUC Energy Efficiency Plan<br /> Max LEED EA points – 50% energy reduction <br />Source: ASHRAE<br />
    19. 19. Case 3: Clean Power<br />for baseline<br /> 30% more renewables (on-site, grid, offsets) <br />Source: Pew<br />
    20. 20. Case 4a: Refurbish<br />for baseline<br /> Replacement of mechanical systems, façades, and finishes at 30th year <br />
    21. 21. Case 4b: Rebuild<br />for baseline<br /> Demolition and rebuild at 30th year <br />
    22. 22. Our Conclusion<br />2: Efficiency<br />3: Clean Power<br />1: Baseline<br />4a: Refurb<br />4b: Rebuild<br />Embodied carbon is 11-50% of 60 yr life-cycle emissions<br />
    23. 23. Wider Context<br />High-performance<br />design<br />Design for<br />Deconstruction<br />Future flexibility<br />© Arup<br />Infrastructure<br />Site<br />
    24. 24. Proposed Overall Approach<br />Load reduction, efficiency, renewables<br />Long-lasting, weatherproof, disaster-resilient systems; Adaptable, flexible space<br />Make use of existing building; Reduce total built area<br />Reclaimed and recycled content; Rapidly renewable and local/regional materials<br />Built-in source separation, chutes; Favor take-back schemes<br />Outreach to occupants; Purchasing policies & waste contracts<br />© Arup<br />
    25. 25. Thanks…<br />Questions?<br />DI Subscription<br />