PIs: John Ochsendorf , Les Norford , and Timothy Gutowski
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Transcript of PIs: John Ochsendorf , Les Norford , and Timothy Gutowski
PIs: John Ochsendorf, Les Norford, and Timothy Gutowski
The Edge of Concrete: The Edge of Concrete: A Life Cycle Investigation of Concrete A Life Cycle Investigation of Concrete
and Concrete Structures and Concrete Structures
The Edge of Concrete: The Edge of Concrete: A Life Cycle Investigation of Concrete A Life Cycle Investigation of Concrete
and Concrete Structures and Concrete Structures
September 13, 2010
Motivations for LCA work
1) Growing demand for quantifying performance of structures
Industry Day – August 31, 2010
Motivations for LCA work
1) Growing demand for quantifying performance of structures
Industry Day – August 31, 2010
Motivations for LCA work
1) Growing demand for quantifying performance of structures
2030 Challenge calls for carbon reductions of:
60% in 2010 (of average carbon emissions for building type)70% in 201580% in 202090% in 2025 Carbon-neutral in 2030
Industry Day – August 31, 2010
Motivations for LCA work
1) Growing demand for improved quantification of green building
2030 Challenge calls for:
60% in 2010 (of carbon emissions 70% in 201580% in 202090% in 2025 Carbon-neutral in 2030
Industry Day – August 31, 2010
Motivations for LCA work
1) Growing demand for quantifying performance of structures
2) Increasing recognition that green design includes the construction phase and the operating phase of buildings
Industry Day – August 31, 2010
Motivations for LCA work
1) Growing demand for quantifying performance of structures
2) Increasing recognition that green design includes the construction phase and the operating phase of buildings
3) Advantages of concrete construction in lowering the emissions in the operating phase
Industry Day – August 31, 2010
Goals of LCA Project
Identify advantages over full life cycle
Identify areas for improvement
Build foundations for future studies
Industry Day – August 31, 2010
Software: GaBi 4
Leading life cycle assessment program
Data for LCA is: Obtained from peer-reviewed sources Taken from in-house database Input from outside sources
Convenient impact assessment interface
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Pavements: Locations and Materials
Concrete versus asphalt roads Analysis currently based on national averages Concentrating on high-volume highways
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Roadway lighting, lane closures, etc.
Model Scenarios
Full Life Cycle Emissions for Different Traffic Volumes
In Summary
Concrete production emissions are higher than asphalt, but concrete use phase emissions are lower High traffic volume concrete highways can have up to 90% lower
emissions for the entire life cycle compared to asphalt highways because of the greater fuel efficiency of vehicles driving on concrete pavements.
But no two pavements are alike The total carbon footprint of a pavement can vary by two orders of
magnitude depending on the traffic volume, rehabilitation schedule, and many other assumptions.
Pavement roughness and deflection are still inaccurate No one has accurately quantified their interactive effects, the effect of
each pavement layer, nor the effect of temperature.
Work for Year Two
Refine our fuel consumption models to better account for pavement-vehicle interactions and to instill greater confidence in fuel savings due to pavement design.
Continue peer review process to have an expert critical review of our LCA study.
Policy Analysis - Analyze scenarios that quantify the carbon emissions associated with proposed renewal and improved upkeep of the national highway system. Combine with life cycle economic costing to understand the
economic impact of reducing greenhouse gas emissions.
Buildings: Locations
Phoenix Chicago
We consider two climate regions in the USWe will expand the studies to other cities
Industry Day – August 31, 2010
LCA Components
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Pre-use phase Use phase End of life
Extraction Heating DisposalManufacturing Cooling RecyclingTransportation Lighting ReuseConcrete Fans TransportationSteel Plug loadsInsulation MaintenanceGlass Energy Mix
Commercial Buildings
Reinforced concrete frames versus structural steel frames in: 12-story commercial office buildings
Industry Day – August 31, 2010
Results
Industry Day – August 31, 2010
Total HVAC:
- 5% Chicago
- 6% Phoenix
CHICAGO PHOENIX
Results
Industry Day – August 31, 2010
Chicago
- 2.5%
Phoenix
- 2.7%
Results
Industry Day – August 31, 2010
Thermal mass provides energy savings over time
Better estimation needed of concrete recycling rates and end-of-life emissions
Even greater advantages are possible for concrete buildings
Next Steps
Industry Day – August 31, 2010
Passive strategies Night cooling Passive solar heating
Active strategies Radiant systems Low-lift cooling
“Predictive Pre-Cooling Control for Low Lift Radiant Cooling using Building Thermal Mass” by N. Gayeski, 2010
Envelope systems
Residential Buildings
Insulated concrete form (ICF) structures versus wood frames in: Two-story single-family residences Four-story multi-family residences
Industry Day – August 31, 2010
• Results based on average quality wood construction, insulated to meet code vs. typical ICF quality construction
• Primary research performed to determine air-tightness of ICF construction• MIT sponsored tests on 15 ICF houses around the country
RESULTS: Single Family Operational Energy
Chicago
- 34%
Phoenix
- 6.3%
Conclusions
• ICF homes deliver substantial energy savings over the lifetime of residential buildings
• Blower door testing revealed that ICF homes offer tight construction with improved energy performance
• Significant further improvements can be made to the life cycle performance of ICF homes
Highlights of LCA Studies in Year One
For a high traffic volume highway, the greater fuel efficiency of vehicles driving on concrete pavements can lead to significantly lower carbon emissions compared to an asphalt pavement. Over a 50-year lifetime, the savings could be as high as 90% of the carbon emissions associated with the pavement selection.
For commercial buildings, the higher thermal mass of concrete buildings can offer savings of 6% of the heating, ventilation and cooling (HVAC) energy consumption for a hot climate such as Phoenix, and 5% of HVAC energy for a cold climate such as Chicago, compared to steel construction. Even greater reductions (up to 25% of operating energy) are possible through improved design of concrete commercial buildings.
For residential buildings, insulated concrete form (ICF) construction can offer HVAC energy savings of 30% or more compared to code compliant wood-framed buildings in a cold climate such as Chicago. Such operational energy savings can compensate for the initial carbon emissions of the concrete within a few decades of operation.
Industry Day – August 31, 2010
Embodied versus operating
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Embodied versus operating
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30% reductionspossible
40% reductionspossible
Next Steps
Complete studies and write reports this fall
Finalize work plans for year two
Integrate new team members
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Thank YouThank YouThank YouThank You