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
| Jun 2, 2014
Nonresidential construction spending expands in April
Ten of 16 nonresidential construction subsectors posted increases in spending in April, according to the latest U.S. Census Bureau data.
| Jun 2, 2014
Parking structures group launches LEED-type program for parking garages
The Green Parking Council, an affiliate of the International Parking Institute, has launched the Green Garage Certification program, the parking industry equivalent of LEED certification.
| Jun 2, 2014
SOM unveils plans for Miami transit hub
The elevated station will be a key portal within All Aboard Florida’s rail system, the nation's only privately owned, operated, and financed rail network.
| Jun 1, 2014
Architect license upon graduation? NCARB aims to accelerate licensing process
Incorporating internship and examination requirements into university education, the regulatory organization looks to simplify and shorten the licensing process.
| May 30, 2014
MIT researchers create 'home in a box' transformable wall system for micro apartments
Dubbed CityHome, the system integrates furniture, storage, exercise equipment, lighting, office equipment, and entertainment systems into a compact wall unit.
| May 30, 2014
Riding high: L.A., Chicago working on their version of the High Line elevated park
Cities around the U.S. are taking notice of New York's highly popular High Line elevated park system. Both Chicago and Los Angeles are currently working on High Line-like projects.
| May 30, 2014
Developer will convert Dallas' storied LTV Building into mixed-use residential tower
New Orleans-based HRI Properties recently completed the purchase of one of the most storied buildings in downtown Dallas. The developer will convert the LTV Building into a mixed-use complex, with 171 hotel rooms and 186 luxury apartments.
| May 29, 2014
Turn your pen-and-paper sketches into digital drawings in seconds with this nifty gadget [video]
Funded through Kickstarter, iSketchnote uses a smart pen to instantly digitize hand-written notes and drawings.
| May 29, 2014
7 cost-effective ways to make U.S. infrastructure more resilient
Moving critical elements to higher ground and designing for longer lifespans are just some of the ways cities and governments can make infrastructure more resilient to natural disasters and climate change, writes Richard Cavallaro, President of Skanska USA Civil.
| May 29, 2014
Wood advocacy groups release 'lessons learned' report on tall wood buildings
The wood-industry advocacy group reThink Wood has released "Summary Report: Survey of International Tall Wood Buildings," with informatino from 10 mid-rise projects in Europe, Australia, and Canada.