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2	Cities: A Reservoir for Concrete Materials
3	Construction Sector and Sustainability Globally, the construction sector has a large impact on Greenhouse Gas (GHG) emissions. Manufacture of cement releases large amounts of CO2 (1 unit cement => 1 unit CO2). Globally, cement contributes 6%-7% of annual CO2 emissions (Mehta, 1998) Solid Waste: Construction debris is a large component of urban solid waste going to landfills Scarcity Issues: Sources of virgin aggregates are getting further away from cities like Denver, increasing transportation costs and fuel use.
4	National: Consumption of Cement
5	National Scarcity of Aggregates
6	Denver – Sources of Virgin Aggregate Sources
7	Some Solutions High Performance Green Concrete Performs as well or better than Ordinary Portland Cement (OPC). Is more durable Has lower environmental emissions Is resource efficient by using recycle/waste streams Examples Fly Ash concrete (FA Concrete) Recycled Concrete (rebar and aggregate)
8	Enter Partnership 1: City & County of Denver Denver’s Mayor signs the US Mayors Climate Protection Agreement in March 2006, joining more than 290 cities who have pledged to take local action for climate protection. Denver’s goal is to reduce its per capita Greenhouse Gas (GHG) emissions by 10% from 1990 per capita baselines by the Year 2011 Denver partners with the University of Colorado Denver to conduct a state-of-the art GHG inventory that would provide baseline data on which to focus Denver’s Climate Action Plan
9	What is New in Denver’s GHG Inventory? City is viewed as a demand center for energy AND key urban materials End-use of energy in all buildings & industries located within Denver is inventoried Transportation energy use by city residents is isolated and inventoried Embodied energy of critical urban materials is included Water, Fuel, Cement in urban concrete, Food/ packaging
10	Sectors Contributing to Denver’s GHG Emissions Buildings/Facilities Energy Use (Greens) Transportation Tail Pipe Emissions (Blues) Embodied Energy of Key Urban Materials (Reds)
11	National Energy Use by Sector
12	Denver’s GHG Inventory Results Per Capita emissions = 25.5 mtCO2e / person Buildings/Facilities Energy Use (Greens) = 52%; Transportation Tail Pipe Emissions (Blues) = 30%; Embodied Energy of Key Urban Materials (Reds) =18%
13	Materials Sector Materials have a significant (18%) impact on Denver’s GHG footprint. Food and packaging wastes contribute 9% to current GHG footprint. Energy recovery from food waste (e.g., restaurant oil waste, biogas) and packaging wastes can avoid some of these emissions. Promoting green fuels such as biodiesel or bioethanol can mitigate another 7% of our current GHG emissions attributed to refining of transportation fuels. Urban concrete alone contributes about 2% to our current GHG emissions, in the same range as all city government operations combined. Green concrete and concrete recycling policies can mitigate these emissions.
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15	Enter Further Collaborations American Coal Ash Association (Fly Ash) Colorado Ready Mix Concrete Association Cement Industry Concrete Recycler (RMC) Regulatory and Other Agencies City Department of Environmental Health Mayor’s Office for Sustainable Development Colorado Department of Transportation (CDOT) USEPA Region 8
16	Policy Workshop: April 13^th, 2006 Stakeholders included: City of Denver Mayor’s Office City of Denver Public Works Department City of Denver Department of Environment Colorado Department of Transportation Environmental Protection Agency – Region 8 Cement and Ready-Mix Industry Recycled Materials Company American Coal Ash Association The primary goals being: Disseminate material science of incorporating wastestream materials into concrete. Identify and track wastestream material sources using GIS Present analysis methods to quantify environmental benefits and costs of high performing green concrete Identify opportunities and constraints toward developing policy
17	Workshop Consensus Recycled and waste stream materials viewed as an important part of sustainable urban concrete Quantifying environmental benefits and costs useful to city policymakers Education of contractors (Residential buildings) seen as important in creating acceptance of high performing green concrete (HPGC) Implications of a HPGC policy needed further study Risk and liability of mandating? Benefits of incentives versus mandates Long term availability of Fly Ash (mercury regulation)
18	Quantifying Environmental Benefits with MFA-LCA: Present Time
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20	Visualizing Future Urban Material Flows using MFA-LCA
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26	Summary of Scenarios: Per unit 1 ton concrete (14% cement)
27	Summary of Scenarios
28	Durability and Life-Cycle Cost
29	Education Component: AMCOR Precast Manhole Pilot
30	Education Component: CCD Cast-in-Place Alley-Slab Pilot
31	Education Component: Rocky Mountain Prestress T-Beam
32	On-going Durability Testing freeze-thaw ASTM C-666 [2003], rapid chloride ion permeability ASTM C 1543 [2002], and sulfate resistance ASTM C-1012 [2004].
33	Ongoing Data Collection Working with Cement Distributors to quantify cement flow in Denver Quantifying long-term concrete demand in Denver Determining long-term material availability of usable Fly Ash (mercury rule)
34	Challenges and Rewards Data from private industry sources Coal Ash Association excellent node for facilitating contacts with power industry Recycled Materials Company provided data Concrete mix associations response variable City became aware of beneficial reuse of FA and recycled concrete aggregates A Fly Ash-Recycled Aggregate Policy in Denver could save more than 55,000 mtCO2e per year Significant cost benefits and durability advantage Same as displacing 12,000 cars, each traveling 12,000 miles per year
35	Policies to Be Discussed Policy 1: Incorporation of HPGC with a minimum FA content set in the City and County of Denver infrastructure to lower carbon footprint. Policy 2: Recycle all concrete infrastructure for use as aggregates and recycled rebar. Part of larger C&D City or Statewide initiative. Mandate or Incentives?
36	Conclusions on Collaborative Research Environmental Life Cycle assessment (LCA) and Material Flow Analysis (MFA) are excellent tools to make visible the environmental benefits and costs of reuse of “waste-stream” materials Role of Academia (UCDHSC) Data from Industry is essential in making MFA-LCA analyses realistic to the region Roles of Coal Ash Association, Recycled Materials Company, Concrete Ready Mix Association, etc. Policymakers seeking broader sustainable development goals consider integrated materials and energy use policies Role of City & County of Denver
37	Acknowledgements David Goss, American Coal Ash Association Rick Givans, Recycled Materials Company Pat Kennedy, Jim Barwick: City and County of Denver - Public Works Gregg Thomas, Kurt Schlomberg: City & County of Denver - Environmental Health Beth Conover, City of Denver, Mayor’s Office – Sustainable Development Initiative