Reducing Embodied Carbon with David Mar - COTE 3/8/2011

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Reducing Embodied Carbon in the built environment will play an increasingly important role in reducing overall carbon emissions over the next 20 years. For buildings, the focus has mostly been on reducing emissions by reducing the use of fossil fuels for operating energy. But we also need to reduce the carbon emissions embodied in the materials and resulting from the construction phase. As buildings become more efficient to operate, the embodied energy and emissions from materials and construction becomes an increasingly significant portion of total GHG emissions.

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Reducing Embodied Carbon with David Mar - COTE 3/8/2011

  1. 1. AIA COTE, San Francisco, CA March 8, 2011Reducing Embodied Carbon in the Built Environment
  2. 2. Resilience is SustainableThere Are No Bad Materials It’s the Cement
  3. 3. The Seismic Environment U.S. Geological Survey: 70% probability of a magnitude 6.7 or larger earthquake in the Bay Area in the next 30 yearsActive E.Q. Faults
  4. 4. Code Seismic Design Throw-away technology: Structure and Architecture absorbs energy through damage Large Inter-story Drifts: Result in architectural & structural damage High Accelerations: Result in content damage & loss of functionDeformed Section – Eccentric Braced Frame
  5. 5. Self-healing Structure • Immediate Occupancy - Green Tag - Minimal Repair Cost and Time • Self Centering Response - No Permanent Tilt - Tough & Damage Resistant • Small Interstory Drift - Protects Façade - Protects Gravity Frame
  6. 6. SF PUC Building Performance Goals High Performance Seismic Design • Immediate Occupancy Value Engineering Savings • $10 million Redesign in Concrete from Steel • After DD complete • Initiated by WebcorArchitect: KMD/Stevens
  7. 7. Steel to Concrete RedesignArchitect: KMD/Stevens Steel Scheme (155 Dampers)
  8. 8. Link Beam OptimizationTrade Partners: Herrick, Harris-Solinas
  9. 9. Link Beam Optimization
  10. 10. Rebar Savings conventional reinforcement post-tensioned reinforcementSave 50% steel
  11. 11. Structural Material MatrixArchitect: BNIM Architects
  12. 12. Structural Material OptionsArchitect: BNIM Architects
  13. 13. The Chartwell School
  14. 14. High Insulation & High Embodied Energy
  15. 15. Resource Efficient Framingconventional framing resource efficient framing Save 30% in lumber as compared to conventional framing Savings allowed FSC lumber
  16. 16. Conductivity Studies Thermal Bridging Framing StudyMechanical Engineer: Taylor Engineering
  17. 17. Low Cement ConcreteLimit cement contentSlag replaces cement (flyash does not)Pozzolanic concrete improves durabilityStrength does not equal to durabilityStronger aggregates need less cement
  18. 18. The Chartwell School Chapin Ready Mix LEED Platinum - Innovation Credit Orinda City Hall Cemex LEED Gold - Innovation CreditThe David Brower Center Hanson LEED Platinum – Innovation Credit San Francisco PUC Central Concrete Supply (in construction)
  19. 19. Fly Ash Fly ash is fine residue produced by the combustion of coal in power stations.
  20. 20. Granulated Blast-Furnace (GGBF) Slag Slag is a nonmetallic product developed simultaneously with iron in a blast-furnace.
  21. 21. Pozzolanic ConcretePORTLAND CEMENT AND CEMENTITIOUS POZZOLANS: CS + H = CSH + CH calcium water calcium calcium silicates silicate hydroxide hydrate (glue) (weak crystals) Pozzolans turn weak crystals into strong crystals NON-CEMENTITIOUS POZZOLANS: CH + S = CSH calcium silica (fly ash or slag) calcium hydroxide silicate (weak crystals) hydrate (glue)
  22. 22. Pozzolanic Concrete 1.15 4% 1.1 6ksi 1.05 50% Fly Ash-F 9%Unit Cost 1 5ksi 0.95 11% 15% 15% Fly Ash-F 0.9 4ksi 0.85 3ksi
  23. 23. Pozzolanic Concrete 1.2 1.15 Relative Cost 6 ksi 1.1 5 ksi 1.05 1 4 ksi 3 ksi 0.95 0.9 0.85 Fly Ash Content 0.8 15% 20% 25% 30% 35% 40% 45% 50% 55% 60%
  24. 24. Pounds per Cubic Yard0 100 200 300 400 500 600 421 lbs 105 lbs cement fly ash-F Pozzolanic Concrete 290 lbs 290 lbs cement fly ash-F 250 lbs 250 lbs 4ksi concrete fly ash -C cement 250 lbs 250 lbs cement slag 200 lbs 200 lbs cement slag 250 lbs 3ksi concrete 150 lbs cement slag
  25. 25. Pozzolanic Concrete
  26. 26. Durability Rapid Chloride Permeability Tests Per ASTM C 1202 at 56 Day Standard Cure 6,000 Charge Passed Chloride Ion Penetrability > 4,000 High 2,000 - 4,000 Moderate 1,000 - 2,000 Low 100 - 1,000 Very Low 5,000 < 100 NeglibilbeCharged Passed (Coulombs) 4,000 100% Cement 3,000 25% Fly Ash 100% Cement 100% Cement 2,000 100% Cement 25% Fly Ash 25% Fly Ash 1,000 25% Fly Ash EF V2 50% EF V2 50% EF V2 50% EF V2 50% EF V2  EF V2  EF V2 EF V2 70% 70% 70% 70% 0 450 550 650 750 Total Cementitious (Lbs)
  27. 27. Set Times
  28. 28. Pounds of CO 2 per Cubic Yard Concrete0 50 100 150 200 250 300 350 400 450100% Portland Cement50% Fly Ash Type F 18% reduction 50% Fly Ash Type C Carbon Dioxide Emission 42% reductionChartwell Mix: 55%70% Slag reduction
  29. 29. SF PUC BuildingArchitect: KMD/Stevens
  30. 30. Concrete Spec Collaboration Mix requirements: 1. Mat foundation: a. Compressive Strength: 8000 psi in 90 days. b. Maximum cement content per cubic yard: 200 lbs. c. CSM content: 70 percent of the total cementitious materials. 2. Core walls and columns: a. Compressive Strength: 8000 psi in 90 days. b. Maximum cement content per cubic yard: 225 lbs. c. CSM content: 70 percent of the total cementitious materials. 3. Post-tensioned concrete slabs and beams (compressive strength to be determined by maturity methods): a. Compressive Strength for stressing: 4500 psi in 3 days. b. Compressive Strength: 6000 psi at 56 days. c. Maximum cement content per cubic yard: 440 lbs. d. CSM content: 45 percent of the total cementitious materials. e. See paragraph 2.09 D in this SECTION for required reflective index.
  31. 31. Low Cement ConcreteArchitect: BNIM Architects
  32. 32. Low Cement Concrete 90 days 56 days 28 days 10 daysSupplier: Central Concrete
  33. 33. SF PUC BuildingKMD/Stevens Mat Slab •Strength 8ksi at 90 days •70% supp. cementitious material •Temp logging system •Maximum cement 200 lbs/yd •CO2 Footprint 335 lbs/yd Baseline •Cement 600 lbs/yd •CO2 footprint 760 lbs/yd •Delta = 425 lbs/yd
  34. 34. Low Cement Concrete Design Concrete Mix Optimization – Sustainability, Performance and Cost Elevated P.T. Slabs •Strength 4.5ksi at 3 days - constructability •Final strength 6ksi at 56 days - structure •45% supp. cementitious material •Minimum Reflective Index 0.7 - lighting •Maturity Testing - mix design •Maximum cement 440 lbs/yd •CO2 Footprint 562 lbs/yd Baseline •Cement 800 lbs/yd •CO2 footprint 944 lbs/yd •Delta CO2 = 382 lbs/ydArchitect: KMD / Stevens
  35. 35. Low Cement Concrete DesignTotal CO2 Savings:• 7,400,000 lbs CO2 reduction• Reduce C02 footprint by 50%
  36. 36. AIA COTE, San Francisco, CA March 8, 2011Reducing Embodied Carbon in the Built Environment

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