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Building Green with Concrete
Amy Miller, P.E.Vice President, National Resources
National Ready Mixed Concrete Association
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National Trade Assn. (Est. 1930)
Silver Spring, MD, based 1100 Member companies 75-80 % - N Amer. Production Advance the Technology & Market
National Ready Mixed Concrete Assn.
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What/Who is NRMCA?
National Ready-Mixed Concrete Association Funded by Member Companies Mission - Serve Industry and Partners Through:
Education Certifications Operations Research & Engineering Codes & Standards Advocacy Promotion Sustainability
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Definitions
What is Sustainable Development? Development that meets the needs of the present
generation without compromising the needs of future generations
Encompasses shelter, food, social welfare, health issues, and ecology
What is Green Building? Focuses on the built environment Minimize environmental impact of buildings A subset of sustainable development
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Triple Bottom Line
TomorrowToday
Social Environment
EconomicGlobal Regional
Local
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Cradle to Cradle Perspective
Material AcquisitionManufacturingConstruction
OperationReuse/Recycling
Life Cycle
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Material Acquisition Phase
Material AcquisitionManufacturingConstruction
OperationReuse/Recycling
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The Bad and The Ugly
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The Good
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Impact of Extracting Materials
Extraction of any raw material has impact on the environment
Natural Resources Canada compared impacts in research study Logging (wood) Iron ore mining (steel) Aggregate quarrying (concrete)
Extracting aggregate for concrete has lower impact than other materials
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Impact Index
Resource Impact Index
ConcreteAggregate QuarryingLimestone Quarrying
1.001.50
Steel Iron Ore Mining 2.25
WoodBoreal Timber HarvestingCoastal Timber Harvesting
2.503.25
Source: Natural Resources Canada
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Logging for Wood
Disruption per unit of building material is high
Renewal takes generations
Stream damage from landslides is common
Source: Natural Resources Canada
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Iron Ore Mining for Steel
Very deep open pit mining
Mines are rarely restored
Duration of disruption may be forever
Source: Natural Resources Canada
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Aggregate & Limestone Quarrying
Closely contained and temporary
Restored within 1 to 2 years
Most abundant materials on earth
Source: Natural Resources Canada
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Manufacturing Phase
Material AcquisitionManufacturingConstruction
OperationReuse/Recycling
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The Bad and The Ugly
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The Good
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Carbon Dioxide
Most materials requires little processing
Low energy of production
Manufactured and harvested locally
Low transportation energy
Contributes to local economy
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Does cement manufacturing generate CO2?
As with all industrial processes Cement generates CO2 Made from natural minerals
calcium (60%) from limestone silicon (20%) aluminum (10%) iron (10%)
Heated in large kiln to 1500° C Converts raw materials to clinker CO2 generated from two sources
Fossil fuels in burning process Calcination - calcium carbonate
broken down to calcium oxide with release of C02
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Cement and CO2
Most common cement is called portland cement Contains about 92% to 95% clinker by weight Some companies produce blended cements
Incorporate industrial byproducts Reduces amount of clinker in the cement
Mining equipment and transportation emit relatively small amounts of CO2
Energy consumption in the U.S. Petroleum refining (6.5%) Steel production at (1.8%) Wood production at (0.5%) Cement manufacturing (0.33%)
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How much CO2 does cement produce?
Between 900 and 1100 kg of CO2 emitted for every 1000 kg of portland cement produced
On average 927 kg of CO2 emitted for every 1000 kg of portland cement produced
50% to 60% is result of calcination remaining is result of burning fossil fuels such
as coal and natural gas
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U.S. Cement CO2 Emissions
U.S. cement industry 1.5% of U.S. CO2 emissions Well below other sources
2005 CO2 Emissions
Transportation 33%
Commercial 18%
Residential21%
Industry28%
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Global CO2 Production
Cement accounts for 3.8% of the global CO2
Global cement production in 2005 Total: 2300 million metric tons (Mt) China: 1038 Mt India: 145 Mt United States: 96 Mt
Global emissions will decrease as countries like China replace old kilns
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Does concrete manufacturing produce CO2?
Water, sand, stone or gravel and other ingredients make up about 90% of concrete
Mining sand and gravel, crushing stone, combining the materials and transportation concrete requires very little energy
Emits a relatively small amount of CO2
Amounts of CO2 embodied in concrete primarily function of cement content
Structures are built with concrete and not cement
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How much CO2 embodied in concrete?
Small percentage embodied in concrete Concrete uses 7% and 15% cement by weight The average quantity of cement is around 250 kg/m3 100 to 300 kg of CO2 embodied per cubic meter That’s 5% to 13% of the weight of concrete CO2 reabsorbed into concrete through carbonation 33% to 57% of CO2 emitted from calcination is
reabsorbed through carbonation over 100-year life
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How does concrete compare to other
building materials in energy consumption?
Concrete has low energy consumption and CO2 emissions compared to: Steel Wood Asphalt
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Concrete vs. Wood Frame
Thermal mass systems save energy Lower CO2 emissions from building occupancy Research study compared energy performance of
various concrete wall systems to wood and steel: Concrete systems reduced energy by 17% Stick-frame house must be 2x12 with R-38 insulation to
achieve same energy performance as insulated concrete wall comprised of 150 mm of concrete and two layers of 60 mm thick rigid insulation
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Concrete Frame Energy Cost Savings
Compared 5-story office building Steel frame with light frame exterior walls Concrete frame with solid concrete exterior walls
5%10%
16%18% 21% 23%
0%5%
10%15%20%25%30%
Miami
Phoenix
Memphis
Chicago
Denve
r
Salem
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Energy of Production
0.251.4222.55
2030
90270
0 50 100 150 200 250 300
AggregatesConcrete
BricksTimber
Reinforced concretePortland cement
GlassSteel
Stainless steelAluminum
Production Energy [GJ/t]
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Concrete Frame vs. Steel Frame
Study compared the CO2 emissions of concrete and steel framed buildings Concrete frame accounted for 550 kg of CO2 per
square meter of floor area Steel frame accounted 620 kg of CO2 per square
meter of floor area
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Concrete vs. Asphalt Pavements
Annual Savings and Reductions for Major Urban Arterial Highway
Results based on driving onconcrete vs. asphalt pavement
Minimum0.8%
Average3.85%
Maximum6.9%
Fuel Savings (liters) 377,000 1,813,000 3,249,000
Dollar Savings ($) 338,000 1,625,000 2,912,000
CO2 Reductions (t) 1,039 5,000 8,950
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RoughnessDeflection
Pavement-Vehicle Interaction (PVI)
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Energy Efficiency Fuel Consumption savings of
3%-17% on PCC pavements
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Other Factors: Heavy trucks get up to 17% better
mileage on concrete – MIT Study. Concrete paving designs and
techniques make concrete roads quiet while maintaining superior skid resistance for increased safety.
No ruts or potholes. Better night visibility. Reduced lighting if using concrete. Completely recyclable. Aids in UHI reduction.
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• Asphalt must be 60% thicker than concrete to provide equivalent stiffness.
Figure 7-3: Impact of PVI deflection over 50 years lifetime at the 95% confidence interval.
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Concrete vs. Asphalt
Life cycle analysis on concrete and asphalt roadways
Compared embodied energy and global warming potential for construction and maintenance over a 50-year life cycle
For a high volume highway Asphalt pavement required 3 times more energy than
concrete pavement Asphalt generated global warming potential of 738 t/km of
CO2 equivalents compared to 674 t/km for concrete
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What is the cement industry doing?
33% reduction in CO2since 1972
Additional 10% reduction by 2020 from 1990 levels
Limestone additions Saves 11.8 Trillion Btus Eliminates 2.5 million
tons of CO2
Reduce waste by 60%
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What is concrete industry doing?
Committed to continuous environmental improvement
P2P Initiative (Prescriptive to Performance Specifications for Concrete)
The P2P Initiative removes limits on materials Allows producers to meet performance
requirements Minimize environmental impact
www.nrmca.org/P2P
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Recycled Industrial Byproducts
Uses of industrial byproducts Fly ash Blast furnace slag Silica fume
Supplement a portion cement Otherwise end up in landfills Called supplementary
cementitious materials (SCMs) Improves strength and
durability Reduces CO2 embodied in
concrete Typical values 15% to 40% As much as 70%
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Construction Phase
Material AcquisitionManufacturingConstruction
OperationReuse/Recycling
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The Bad and The Ugly
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The Good
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Concrete Construction
Made specifically for each order
Little to no waste is generated
Short transport No shipping carton or
wrapping Leftovers
landscaping blocks Traffic barriers
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Batch fresh materials
Reship
Paving at plant
Settling pond
Truck wash, batch plant or
discharge after treatment
Solids to landfill
Blocks
Reclamation
Windrow & Crush
Returned Concrete Options
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Operational Phase
Material AcquisitionManufacturingConstruction
OperationReuse/Recycling
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The Bad and The Ugly
United StatesOther of G7 countriesRest of the world
5%
88%
7%
25%
19%
56%
Population Energy Consumption
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Operational Energy
Residential Bldgs
Commercial Bldgs
Industry
Transportation
21%
18%
28%
33%
United StatesOther of G7 countriesRest of the world
25%
19%
56%
US buildings alone use almost 10% of the world’s energy!
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The Good
High Performance Envelopes Insulation on the outside
of wall or roof Mass in contact with
interior space Superior building
envelope
Concrete Walls
Concrete FloorsAnd Roofs
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Thermal Mass
Increase thermal lag Off peak demand Lower energy costs
Lower peak energy Smaller, more efficient
HVAC equipment
Reduce temperature swings Less heating and cooling
energy required
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High Performance Wall Systems
Tilt-up Concrete Walls
Insulating Concrete Forms
Removable FormSystems
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Alvaton Elementary School - 2006
Warren County Schools
Bowling Green, Kentucky
750 Student Capacity
77,000 sf
SCB: Case Study
• ICF Exterior wall construction
(First ICF School in the Nation!)
• Geothermal heating and cooling
• Sandwich panel metal roof
system R-30 insulation value
• Lighting and HVAC motion
sensors
• Daylighting
• Energy efficient glazing at
windows
• GREENGUARD certified interior
finishes
High Performance Features:
35 kBtu/sf/year
$167,259 Savings Annually
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Hearn Elementary School - 2008
Franklin County Schools
Frankfort, Kentucky
550 Student Capacity
67,853 sf
SCB: Case Study
• ICF Exterior wall construction
• Geothermal heating and cooling
• Automatic building shut-down
system
• Daylighting
• Energy efficient glazing at
windows
• GREENGUARD certified interior
finishes
High Performance Features:
36 kBtu/sf/year
$164,401 Savings Annually
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Energy Cost Case Studies
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ICF Wall On the left an ICF wall; On the right a traditional CMU wall
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Energy Standards
Thermal mass addressed in building codes
Buildings ASHRAE 90.1
Low-rise residential ASHRAE 90.2
One- and two-family ICC International Energy
Conservation Code
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Urban Heat Island Effect
Residential zones are 3° warmer
Downtown areas are 7° warmer
Due to dark-colored roofing and pavement
Source: Lawrence B. Livermore National Laboratory
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Urban Sprawl
NASA Thermal Images of Atlanta
1973 1979 1983
1987 1992 1997
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Concrete Parking
Concrete Parking Garage
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Cool Communities – US DOE
Use light colored roofing and cladding
Use light colored pavements
Landscape shading Reduce air
temperatures by 5° Reduce air conditioning
by 18%“The offset in carbon emissions from replacing the world's roofs and
pavements with reflective white and light-colored surfaces is roughly
equivalent to taking the world's approximately billion cars off the road
for 11 years.” – Steven Chu, former DOE Secretary
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Roofing and Cladding
Concrete roofing and cladding Light colored Highly reflective
Research shows 40% reduction in cooling energy
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Pavement and Landscaping
Concrete pavement and landscaping
Article in MIT Technology Review “…blacktopping should
be discontinued…” Use light-colored
pavements Concrete costs slightly
more but has a lower life cycle cost
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Reduced Lighting Requirements
30% fewer fixtures can produce the same level of lighting on concrete compared to asphalt
Asphalt Concrete
Source: Road Surface’s Reflectance Influences Lighting Design” RP269.01P, R. E. Stark, Portland Cement Association, April 1986.
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Stormwater Management
Pervious Concrete 15-30% voids Rainwater percolates
through the slab Minimizes runoff to
surrounding streams and lakes
Functions like retention basins
Recharges groundwater supplies
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Indoor Air Quality
Building MaterialVOC Emission
(mg/m3h)
Vinyl flooring 2.3
Particle board 2.0
Plywood 1.0
Acrylic Latex Paint 0.43
Linoleum 0.22
Carpet 0.080
Gypsum board 0.026
Concrete 0.003
Source: University of Western Ontario
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Reduce VOC Emissions
Use exposed concrete: Decorative floors Textured walls Exposed ceiling
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Durability and Versatility
Most widely used building material
Extremely durable Doesn’t rot Doesn’t rust Doesn’t burn
Low maintenance 2000 year track record
of performance
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Reuse/Recycling Phase
Material AcquisitionManufacturingConstruction
OperationReuse/Recycling
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Committed to continuous environmental improvement
P2P Initiative (Prescriptive to Performance Specifications for Concrete)
The P2P Initiative removes limits on materials Allows producers to meet performance
requirements Minimize environmental impact
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Supplementary Cementitious Materials
Fly ash From coal-fired electrical
power plants
Blast furnace slag From steel manufacturing
Silica Fume From silicone
manufacturing
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Specifying SCMs
Concrete: Reference ASTM C 94 Permits the use of SCMs
Fly ash: Reference ASTM C 618 Replace from 5 to 65 percent
Blast furnace slag: Reference ASTM C 989 Replace from 20 to 70 percent
Silica fume: Reference ASTM C 1240 Replace from 5 to 12 percent,
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Key to high performance
High Performance Improves durability Increases strength Improves constructability
Environmental Benefits Reduces waste Reduces raw material
extraction Reduces energy of
production Reduces CO2
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Recycled concrete
Fills and bases Roadways and parking
areas Driveways and sidewalks Shoulders, curbs, gutters
Landscaping features Foundations Some Concrete
Structures
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RECENT CHANGES
Architecture 2030’s “2030 Challenge for Products” dramatic reductions in energy
consumption and greenhouse gas emissions to manufacture and transport materials
LEED v4 Material Disclosure and Optimization does away with credits for recycled content and regional materials and replaces with MDO requiring material suppliers to submit EPDs
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LEED v4 MR Credits
Global warming potentialDepletion of stratospheric ozone layerAcidification of land and water sourcesEutrophicationFormation of tropospheric ozoneDepletion of nonrenewable energy
Land useWater useBiodiversityHuman rightsNoise
Human health (cancer)Human health (non-cancer)
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Point System
Option 1 – EPDs (1 point)20 Permanently Installed Products Product specific declaration –
publicly available (1/4 product) Industry average EPD – Third
party certified Type III (1/2 product)
Product specific EPD – Third party certified Type III (Full product)
USGBC Approved Program
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Point System
Option 2 – Multi-Attribute Optimization (1 point) 50% by Cost Environmental Impact Reduction below
industry average– USGBC Approved Certification Program – (100% Value) GWP Ozone depletion Eutrophication Smog formation Acidification Depletion of nonrenewable energy
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OPPORTUNITY Demanded by A/E Firms
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