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.

1. AIA COTE, San Francisco, CA March 8, 2011
Reducing Embodied Carbon in the Built Environment

2. Resilience is Sustainable
There Are No Bad Materials
It’s the Cement

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 years
Active E.Q. Faults

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 function
Deformed Section – Eccentric Braced Frame

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. 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 Webcor
Architect: KMD/Stevens

7. Steel to Concrete Redesign
Architect: KMD/Stevens
Steel Scheme (155 Dampers)

8. Link Beam Optimization
Trade Partners: Herrick, Harris-Solinas

9. Link Beam Optimization

10. Rebar Savings
conventional reinforcement post-tensioned reinforcement
Save 50% steel

11. Structural Material Matrix
Architect: BNIM Architects

12. Structural Material Options
Architect: BNIM Architects

13. The Chartwell School

14. High Insulation & High Embodied Energy

15. Resource Efficient Framing
conventional framing resource efficient framing
Save 30% in lumber as compared to conventional framing
Savings allowed FSC lumber

16. Conductivity Studies
Thermal Bridging Framing Study
Mechanical Engineer: Taylor Engineering

17. Low Cement Concrete
Limit cement content
Slag replaces cement
(flyash does not)
Pozzolanic concrete
improves durability
Strength does not equal
to durability
Stronger aggregates
need less cement

18. The Chartwell School Chapin Ready Mix LEED Platinum - Innovation Credit
Orinda City Hall Cemex LEED Gold - Innovation Credit
The David Brower Center Hanson LEED Platinum – Innovation Credit
San Francisco PUC Central Concrete Supply (in construction)

19. Fly Ash
Fly ash is fine residue produced by
the combustion of coal in power
stations.

20. Granulated Blast-Furnace (GGBF) Slag
Slag is a nonmetallic product
developed simultaneously with iron in
a blast-furnace.

21. Pozzolanic Concrete
PORTLAND 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. 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. 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. Pounds per Cubic Yard
0
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. Pozzolanic Concrete

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 Neglibilbe
Charged 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. Set Times

28. Pounds of CO 2 per Cubic Yard Concrete
0
50
100
150
200
250
300
350
400
450
100% Portland Cement
50% Fly Ash Type F
18%
reduction
50% Fly Ash Type C
Carbon Dioxide Emission
42%
reduction
Chartwell Mix:
55%
70% Slag
reduction

29. SF PUC Building
Architect: KMD/Stevens

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. Low Cement Concrete
Architect: BNIM Architects

32. Low Cement Concrete
90 days
56 days
28 days
10 days
Supplier: Central Concrete

33. SF PUC Building
KMD/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. 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/yd
Architect: KMD / Stevens

35. Low Cement Concrete Design
Total CO2 Savings:
• 7,400,000 lbs CO2 reduction
• Reduce C02 footprint by 50%

36. AIA COTE, San Francisco, CA March 8, 2011
Reducing Embodied Carbon in the Built Environment