MIT Concrete Sustainability Hub Bruce McIntosh, Portland Cement Association Topics • HUB background • Life-cycle assessment of pavement • Life-cycle assessment of buildings and homes • Econometrics • Green concrete science MIT Concrete Sustainability Hub • Established by PCA and RMCREF • $10 million investment over next 5 years • Validate and innovate: – Identify areas in which concrete excels – Identify opportunities for improvements – Create solid technical basis for future industry development R&D Platforms • Concrete Science • Building Technology • Econometrics Concrete Science Platform • Mission: Scientific breakthroughs toward reducing CO2 footprint of cement and concrete • Breakthroughs would imply: – Strength with less material – Lower energy processing – Chemical stability Building Technology Platform • Mission: Life-cycle assessment (LCA) of concrete buildings and pavements to identify impacts and opportunities Econometrics • Mission: Assess the impact on jobs and the economy of sustainable advancements in cement and concrete Building Technology: Paving • 8 million lanemiles • 3 trillion vehiclemiles / year • 27% of U.S. GHG emissions from road transportation Improving Paving Performance • Comprehensive methodology for pavement LCA • Quantifying greenhouse gases • Investigate pavementvehicle interaction Life-Cycle Analysis Opportunities from LCA: • “Cradle-to-cradle” analysis • Large impacts beyond initial manufacturing • Use-phase impacts Use-Phase Impacts • • • • Fuel consumption Urban heat islands Street lighting Carbonation Indirect impacts • Traffic delays • Additional materials and energy • Construction equipment emissions • Material waste Key findings • Whole life LCA needed to capture all impacts • Use and maintenance phases account for 33% to 44% of CO2 for interstate highways Pavement-Vehicle Interaction • Demonstrates of fuel savings with concrete • Two factors: stiffness and roughness Stiffness Roughness Stiffness or Deflection • Rigid pavements produce less rolling resistance and better fuel economy Stiffness Stiffness or Deflection • Asphalt roads need to be 25% to 60% thicker to achieve same fuel efficiency as concrete. • Goal is to assess impacts of pavement properties on fuel consumption for both environmental impact and cost savings. 50-year GHG Emissions PVI (Deflection) Production + M&R GHG Emissions (Mg CO2e) 2500 2000 1500 1000 500 0 Concrete Asphalt High Volume Concrete Asphalt Arterial Building Technology: Structures • Life-cycle analysis research for single-family housing, multifamily housing, and commercial structures Why are Buildings Important? 56% 25% 18% Commercial Bldgs 21% Residential Bldgs 26% Transportation 19% 35% United States Other of G7 countries Rest of the world Industry Buildings Life-Cycle Analysis • Examining materials within whole building context, not just manufacturing and initial construction • Consider use and operations phases Single-Family Housing • Single family homes represent 80% of total residential energy consumption Multi-family 80% Single family Single-Family LCA • Exterior walls • Wood frame and insulating concrete forms • Quantity of insulation • Thermal mass Key Findings • Concrete homes produce 5% to 8% lower GHG emissions. • Concrete homes use 8% to 11% less energy. • Concrete wall systems have higher embodied energy, but that accounts for only 2% to 12% of GHG over a 60-year service life. Next Steps: Air Tightness • Not considered in initial study, but represents greatest potential for additional improvement • Improvement from average to tight saves 23% of total operating energy Commercial Buildings • Commercial buildings represent 18% of U.S. energy consumption Commercial LCA • Compares steel and concrete structural frames • Floor to floor heights identical • 12-story building with 40% glazing Key Findings • No greater embodied energy than comparable steel frames • Energy savings when concrete frame is exposed are 3%; when covered by finishes, 2%. • Active use of the thermal mass capability of concrete slabs could result in significant savings Econometrics • Study on life-cycle cost analysis” for highways, “The Effects of Inflation and Its Volatility on the Choice of Construction Alternatives.” • Study examines historical data on real prices of construction materials. Key Findings • Traditional analysis uses the same escalation rate for concrete and asphalt . • Assumption of constant real costs can lead to serious cost overruns. • Study suggests the use of materialspecific escalation rates. Advocacy and Promotion • Working with state and federal officials to incorporate MIT findings in life-cycle analysis models • Focus of ad campaign • Goal: Level playing field for concrete and asphalt. Ad Campaign Concrete Science Platform 1. Alite/belite reactivity 2. Aluminate reactivity 3. Alkali effects 4. Water and dissolved components 5. Mechanical properties of materials Concrete Science Platform • Industry/MIT collaboration • Significant progress on key topics: – Alite/belite reactivity – Water and dissolved components – Mechanical properties of materials More Information • http://web.mit.edu/cshub/ MIT Concrete Sustainability Hub Bruce McIntosh, Portland Cement Association