An interesting 5 year study that compares the performance of three homes nearly identical that are inhabited by robotics that simulate actual human behavior.
The three homes have identical floor plans, square footage, and have their broad sides facing the sun. The difference was the materials in the building envelop, the HVAC and the lighting.
What was the cost difference in construction of the three buildings?
According to David Dinse, senior program manager for technology innovation at TVA, “It cost around $30,000 more to build the high performance energy home compared to the normal build, but today it would be more like $20,000 because the cost of a lot of materials has gone down since we built these. What they started experimenting here five years ago is becoming the new standard for building.”
What was the difference in utility bills for the 5 year period?
“The build-house had a utility bill of $1,600 a year. The retrofit was $1,000. And this [high performance] was a shade over $400. Most of that difference is the solar buyback plan,” said Dinse. “It actually surprised me that the kilowatt hour basis, there was not that much difference between this house and the retrofitted house if you strip the solar off. But I think you have to cherry-pick the best things from both houses and pick the sweet spots that don’t add a whole lot of cost to come out with the optimum design.”
If the high performance building costs $20,000 more and the savings between the build house and the high performance is $400 …That would be a 17 year payback and that is only because of the solar buyback program. If it was based on energy savings not cost then the payback would be around 33 years.
Not such great results.