There is a real-world case study taking place right now in Midland, Michigan. Spearheaded by Dow Building Solutions and Cobblestone Homes, the Twelve Energy Efficiency Test Homes (TEETH) Project was several years in the making. Home construction was completed in 2011 and the full study finally launched in fall of 2012 after the last home was occupied. The goal of this project is to create the first-ever forum for real-world, real-time measurements that track and capture data of high-performance homes.
While there have been dozens of scientific-model studies conducted in the last decade to predict energy efficiency in residential construction, this is the nation’s first active subdivision specifically designed to capture quantitative and qualitative data.
The TEETH project, a five-year study, recently wrapped up its first year of data collection. Throughout the year, it generated comparative data on home energy efficiency based on whole-house insulation, air-sealing systems and real-world living conditions. The study is also providing comprehensive data on energy consumption, humidity, moisture levels, heat flow and temperature.
In addition to that valuable data that is being collected, Dow also wanted to determine exactly what it costs to build to the 2012 International Energy Construction Code (IECC). At the time this project was being developed, Michigan was considering changing its energy code from 2006 to either 2009 or 2012.
Brian Lieburn, Residential Applications Development Leader for Dow Building Solutions, explains, “During this time, we heard a vast range of cost estimations being suggested. For instance, a typical 2,000 s.f. to 2,400 s.f. home was estimated to cost between $7,000 to over $20,000 to meet the 2012 IECC standards.”
That significant range in projected costs motivated Dow to develop this study based on the 2006 and 2012 IECC. “It made sense for us to build some homes to the 2006 IECC and some to the 2012 IECC and track costs carefully to see how much it really does cost,” says Lieburn. “That’s the only way to truly know.”
Home Construction Break-Down
For this real-world study, Dow selected three different floor plans – two single-story and one two-story – and each was built at four different energy-performance levels.
- The first set of three homes was built to the 2006 IECC.
- The next set of six homes was built to 2012 – using two different energy-performance strategies:
- One set was built to the specifications that Dow thought most builders would use to meet the 2012 IECC. This method makes the least amount of changes in the way most builders were building to meet the 2006 IECC.
- The other three homes were built to the Dow-preferred method, which is a way to “out-perform” the 2012 IECC standard.
- The final group of three homes was built to beyond the 2012 IECC and to be net-zero energy ready.
“We selected the most common-sized home – approximately 2,000 to 2,400 s.f. of living space – with each home featuring a different combination of insulation and air sealing improvements, including continuous insulation closed-cell spray foam insulation and insulating foam sealant,” explains Lieburn.
To ensure the validity of the study, each home was uniformly built to careful standards that were designed to mitigate variances, including orientation to the sun and grade. “All 12 homes are located in the same subdivision, with nine of the 12 side by side on the same street. They are getting the same solar, wind and noise exposure,” Lieburn continues. “All of these things help us gauge what people’s impressions are of these different performance strategies – particularly when it comes to comfort.”
With all of the coordination that it takes to develop a research project of this magnitude, the biggest challenge Dow Building Solutions ran into wasn’t what you would expect. “It is hard to get a good builder to build a not-so-good home” jokes Lieburn. “Cobblestone Homes is a builder who believes in good building science, and while ideally we wanted the lowest-standard home that could be built to meet the 2006 IECC, we didn’t get that with Cobblestone – nor, quite frankly, were we expecting that out of them.”
In fact, the three 2006 IECC homes that were built averaged a 77 HERS score – which is considerably better than the 2006 IECC minimum. “That’s a testament to Cobblestone; they know how to build a tight home that is well insulated.”
First Year Completed & Moving Ahead
While the homes were built in 2011, they all weren’t fully occupied until the summer of 2012, so the research didn’t begin until the winter season of 2012-2013. Being part of a real-world study, each family lives in its home differently. This will be a major factor in this study and will need to be looked into to help explain why one house doesn’t use as much energy as another. “This is the reason why we are conducting a real-world study, as opposed to plugging numbers into a scientific model,” says Lieburn. “Occupants matter.”
He concludes, “Right now we have completed our first year of data collection, and there is some interesting information to share during our presentation at the Builders’ Show next February.”
Brian Lieburn is the Residential Applications Development Leader for Dow Building Solutions. He and Mark Wahl, principal of Cobblestone Homes, LLC will be presenting, Real World Michigan: 12 Test Homes Examine the True Value of High Performance Building at the Builders’ Show on February 6. For more information on this session and the 100+ other educational sessions being offered, visit BuildersShow.com.
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