The need to decrease energy usage and subsequent emissions from the building sector has been at the forefront of U.S. green movement. Not only has energy reduction been viewed as a step for improving the environment, it has financial benefits for companies and homeowners.
To address this, researchers at the Massachusetts Institute of Technology’s (MIT) Concrete Sustainability Hub conducted a life-cycle assessment (LCA) study to evaluate and improve the environmental impact and study how the “dual use” aspect of concrete – its ability to offer a durable structure while providing thermal mass benefits for energy loads – affects the environmental footprint of the structure.
"Methods, Impacts, and Opportunities in the Concrete Building Life Cycle" provides a comprehensive analysis that advances three key areas relevant to the buildings LCA field: methodology, benchmarking, and impact-reduction opportunities. The study is a major development for construction-related life-cycle assessment because it thoroughly examines all phases of the complete life cycle of a building – from acquisition of materials to construction, the use of the building, and finally demolition and end of life.
“Most environmental assessments do not move beyond the construction phase and only provide a partial picture of the full impact a particular material can have on a building. This is short-sighted,” David Shepherd, director of sustainable development for the Portland Cement Association (PCA) said. “The heating, cooling, and general operations of buildings and homes in the United States accounts for approximately 70 percent of national energy consumption each year and an accurate LCA needs to include the operational phase.”
Concrete, essential for the construction of buildings and homes, has largely been chosen as a building material for its structural properties rather than its energy-saving properties. Although sustainable builders have known the thermal mass attributes of concrete significantly reduce heating and cooling needs, the energy consumption required to produce its key ingredient, cement, has raised questions about its environmental viability.
In its environmental assessment, MIT researchers found concrete homes produce lower greenhouse gas emissions than current best practice code – compliant wood-frame residences throughout a 60-year service life.
Concrete homes did have a higher embodied global warming potential (GWP) associated with the pre-use phase of LCA when raw materials are harvested and turned into construction materials, transported to the site, and assembled into the finished home. However, this phase accounts for only about 2 to 12%of the overall global warming potential for the life of the home. For the 60-year period of the study, houses constructed with insulated concrete forms have 5 to 8 percent lower GWP than current code compliant light frame wood houses, based on greater thermal mass and higher R-values. Researchers found similar results when evaluating multifamily residences.
Commercial office buildings built with a concrete structural frame produce slightly less greenhouse gas emissions over a 60-year service life than commercial structures built with steel frames, based on the results of the comprehensive MIT assessment.
MIT researchers then evaluated strategies to lower a concrete building’s carbon footprint and overall environmental impact. A major advancement was the incorporation of a cost-impact analysis to determine whether or not a given environmental reduction strategy made economic sense. Among the strategies evaluated, the two that reduced embodied emissions – increased fly ash and reducing the thickness of concrete walls from a 6-inch to a 4-inch concrete core – were found to be both economical and effective ways to reduce emissions. BD+C
Related Stories
| Dec 14, 2011
Tyler Junior College and Sika Sarnafil team up to save energy
Tyler Junior College wanted a roofing system that wouldn’t need any attention for a long time.
| Dec 13, 2011
Lutron’s Commercial Experience Center awarded LEED Gold
LEED certification of the Lutron facility was based on a number of green design and construction features that positively impact the project itself and the broader community. These features include: optimization of energy performance through the use of lighting power, lighting controls and HVAC, plus the use of daylight.
| Dec 12, 2011
AIA Chicago announces Skidmore, Owings & Merrill as 2011 Firm of the Year
SOM has been a leader in the research and development of specialized technologies, new processes and innovative ideas, many of which have had a palpable and lasting impact on the design profession and the physical environment.
| Dec 12, 2011
Skanska to expand and renovate hospital in Georgia for $103 Million
The expansion includes a four-story, 17,500 square meters clinical services building and a five-story, 15,700 square meters, medical office building. Skanska will also renovate the main hospital.
| Dec 12, 2011
CRSI design awards deadline extended to December 31
The final deadline is extended until December 31st, with judging shortly thereafter at the World of Concrete.
| Dec 12, 2011
Mojo Stumer takes top honors at AIA Long Island Design Awards
Firm's TriBeCa Loft wins "Archi" for interior design.
| Dec 10, 2011
10 Great Solutions
The editors of Building Design+Construction present 10 “Great Solutions” that highlight innovative technology and products that can be used to address some of the many problems Building Teams face in their day-to-day work. Readers are encouraged to submit entries for Great Solutions; if we use yours, you’ll receive a $25 gift certificate. Look for more Great Solutions in 2012 at: www.bdcnetwork.com/greatsolutions/2012.
| Dec 10, 2011
Energy performance starts at the building envelope
Rainscreen system installed at the west building expansion of the University of Arizona’s Meinel Optical Sciences Center in Tucson, with its folded glass wall and copper-paneled, breathable cladding over precast concrete.