Jeremy Gregory, Executive Director, Concrete Sustainability Hub (CSH) of Massachusetts Institute of Technology (MIT): Presentation from the 12th CSI Forum: Cement & Concrete: From Linear to Circular, 2018.

1. Quantitative evaluations of circular
economy solutions
Jeremy Gregory
Executive Director, MIT CSHub
CSI Forum 2018
October 9-10, 2018
Chicago, IL USA

2. Slide 3
Resource use is unsustainable
Source: UNEP (2011) Decoupling natural resource use and environmental impacts from economic
growth, A Report of the Working Group on Decoupling to the International Resource Panel.

3. Slide 4
Construction & demolition quantities are huge
Concrete
70%
Asphalt
15%
Wood
7%
Shingles
3%
Drywall
2%
Brick
2%
Steel
1%
The US generates over 550 million tons of C&D waste per year –
more than twice the amount of generated municipal solid waste
5% of the waste is generated during construction
Source: US EPA, 2015

4. Slide 5
Buildings have a significant environmental footprint

5. Slide 6
Transitioning to a circular economy would enable sustainable
materials management
Material
Production
Construction Use End-of-Life
Material
Production
Construction
Use
End-of-Life
Linear Economy
Circular Economy
Circular economy in the
buildings and infrastructure
sector is challenging due to:
• Complexity of B&I
• Use of multiple materials
and assemblies
• Long lives

6. Slide 7
A life cycle perspective is key for evaluating
circular economy solutions
Materials
Production
• Use recycled
content
• Improve
performance
Design &
Construction
• Use less
(i.e., stronger)
material
• Create longer-
lasting designs
Use
• Reduce energy
consumption
• Reduce hazard-
induced repairs
• Minimize
maintenance
End-of-Life
• Enable material
recovery
• Plan for
component
reuse
Evaluate trade-offs among solutions

7. Slide 8
LCA – Life-cycle assessment:
Method for quantifying environmental impact
Materials
Production
Design &
Construction
Use End-of-Life
Activity
Raw
Materials
Energy
Product
Air
Emissions
Water
Effluents
Releases to
Land

8. Slide 9
Building life cycle perspective is important
0
400
800
1200
ICF
Wood
ICF
Wood
ICF
Wood
ICF
Wood
Concrete
Steel
Concrete
Steel
Chicago Phoenix Chicago Phoenix Chicago Phoenix
Single Family Multi-Family Commerical
Embodied Impact Energy Use over 60 years
Exterior Wall
Building Type
Location
Building Life
Cycle
Global
Warming
Potential
(lbs CO2/ft2)
Ref: Methods, Impacts, and Opportunities in the Concrete Building Life Cycle
Energy use
Embodied

9. Slide 10
ReSOLVE Circular Economy Framework
Source: Ellen MacArthur Foundation
Building strategies:
• Maximizing value from C&D waste
• Design for material and component reuse
• Design for long life and adaptability
• Enable CE design and construction
practices through increased use of digital
technology and advanced automation
• Transforming finance mechanisms and
regulations to incentivize CE strategies
Evaluate trade-offs among solutions

10. Thank you
http://cshub.mit.edu/
jgregory@mit.edu