Can residential construction using insulated concrete forms, or ICFs, be more cost-effective and environmentally friendly than current building practices? That’s what new industry-sponsored research from the Massachusetts Institute of Technology contends.
In an effort to “deliver a new level of clarity” about the life-cycle performance of structures that include single-family homes, MIT’s Concrete Sustainability Hub, a research team, on Thursday released an interim report of a year-long investigation into the potential energy savings in homes constructed with ICFs.
The Portland Cement Association and the Ready-Mix Concrete Research Foundation are funding the Hub’s research, which it expects to complete by next August. Its goal, according to co-director John Ochsendorf, an associate professor for MIT’s departments of architecture and civil and environmental engineering, is to come up with a model for assessing the carbon emissions of buildings during a 75-year period. This model is also intended “to demonstrate the potential energy savings due to the benefits of thermal mass, effective insulation, and reduced air infiltration,“ which the report contends are inherent in ICF.
In a teleconference, Ochsendorf said his team would be using in its assessments the U.S. Department of Energy’s benchmark buildings, which number 5,000 across the country. According to the executive summary released Thursday, those buildings include both two-story homes of 2,400 square feet that are wood-framed and ICF-made as well as multifamily four-story structures that are L-shaped, with a typical floor plate area of 2,900 square feet.
During the year of analysis, Hub researchers discovered that:
• The advantages of higher R-value and lower thermal bridging enable ICF homes to deliver energy savings in heating, cooling, and ventilation compared to conventional wood-framed construction.
• For residential buildings, ICF construction can offer operational energy savings of at least 20% compared to code-compliant wood-framed buildings in a cold climate such as Chicago.
• More than 90% of the life-cycle carbon emissions are due to the building’s operation phase, with construction and end-of-life disposal accounting for less than 10% of the total emissions.
The three keys that make this research unique, said Ochsendorf, are its “comprehensiveness” (in that it includes the buildings’ energy use in its assessments), its combination of life-cycle environmental assessments with economic cost analysis, and its benchmarking of the structures’ performance “to create a road map for better infrastructure in the future.”
Over the next several months, the Hub team intends to expand its research to more climate zones, explore the potential energy savings related to passive technology in concrete homes, and quantify the life cycle economic performance of concrete residential construction.
In an interview with BUILDER, Ochsendorf conceded that the higher construction costs which builders typically ascribe with energy efficiency continue to be “an honest-to-God barrier” to better building, especially when builders are hardly ever the operators of what they build, so their concerns about long-term post-construction energy efficiency often end at the closing.
Ochsendorf adds that there’s a lot more that builders could be doing to make their homes more efficient, starting with maximizing the house’s window exposure to sunlight and wind. “There’s an awful lot of low-hanging fruit builders could be picking to re-imagine what buildings should be.”
He adds that throughout history, dating back to Roman times, home builders across the world “have responded to their climates,” and he’s waiting for cultural shifts that might lead to that same response in the United States.
On a separate track, the Hub's team of researchers is also making life-cycle assessments of road pavements.
John Caulfield is senior editor for BUILDER magazine.