The Tennessee Valley Authority (TVA) has learned some valuable lessons from a study involving the use of robotics to simulate human behavior. The results show that dramatic improvements in efficiency can be obtained with a combination of new technology and a focus on energy efficient construction techniques.
The 5-year Campbell Creek project involved three similar Knoxville, Tennessee-area homes. Each has the same floor plan, with two stories, and measures between 2,400 and 2,500 square feet. Here is how they differ:
- Builder House: This was the control home, or benchmark, built to represent a typical residence constructed for the Tennessee Valley and built to local building codes.
- Retrofit House: This house was essentially the Builder House, but retrofitted with energy efficiency technologies, such as more energy efficient windows, ENERGY STAR appliances, compact fluorescent lights, sealed attic with foam insulation, and high efficiency heat pumps.
- High Performance House: This house was built using the latest available construction technologies aimed at energy efficiency, as well as PV panels and solar water heating to help make it a near zero energy house.
The TVA then outfitted each home with robotic devices to mimic human behavior. For example, a robotic arm on the refrigerator in each home would open the door simultaneously at 3:00 in the afternoon, when kids typically arrive home from school. Each home had the same automated systems to turn on lights, televisions, appliances, and showers. The homes also had a device that replicates how a person’s body heat affects the temperature and humidity of a room. In addition, each home had hundreds of sensors installed to monitor energy consumption of all the subsystems.
Results and Lessons
The Builder House had a utility bill of about $1,600 a year, the Retrofit about $1,000, and the High Performance was slightly more than $400, according to project managers. Based on the Home Energy Rating System (HERS) Index, the homes scored as follows: Builder House, 101; Retrofit House, 68; and High Performance House, 34 (a lower score is better).
The TVA project was conducted with partners Oak Ridge National Laboratory (ORNL) and Electric Power Research Institute (EPRI). Near real-time data from the project as well as archived results are available at the EPRI web site.
These are not exactly startling results, but this intriguing study has valuable lessons for all stakeholders – utilities, homebuilders, and homeowners. One main lesson is that doing basic things like tightening a home’s envelope with enhanced insulation and energy efficient windows will have lasting benefits. Also, investing in the most efficient HVAC and water heating systems one can afford will pay off in energy savings. The manager of the project, David Dinse, who has just retired, told me the project has generated quite useful data – so why aren’t more builders and utilities taking these lessons and running with them?