Let's Play Stump the Chump!
Send in your stumpers!
You know—that problem house, symptom or combination of symptoms that confounded the homeowner and challenged all your building science savvy to solve. Send BPI a description of the problem—and the solution, which will be kept secret. If it's a genuine stumper, it may be published in the next HVAC2HP e-newsletter. Send stumpers to firstname.lastname@example.org.
This stumper is reprinted with permission from BPI.
Answer to Last Month's Stumper:
A big thatta-boy-thump on the back for Kevin Grothe of the Community Action Partnership of Ramsey and Washington Counties in Vadnais Heights, Minnesota for being the first person to submit a correct answer to last month's Stump the Chump!
As a reminder, Ed Revers of Michell Timperman Ritz Architects in New Albany, Indiana was scratching his head about a 50-year-old home with energy bills that were far too high after the installation of a top-of-the line Florida Heat Pump System with all of the energy saving bells and whistles, and the construction of an addition.
Many of you guessed the system was oversized and short cycling, and that air leakage and thermal bridging might play some minor role. Kevin went a totally different way, suggesting a difference in the occupants' comfort settings, which was key here.
Ed explains that "before the addition, the occupants complained of terrible air distribution patterns, significant hot/cold spots throughout the house, and kept the temp 5 or more degrees in the uncomfortable range in order to save energy costs. After the addition was built, insulation was added, zoning and ductwork improvements were installed, and a new mechanical system was complete, the temperature was set to a significantly more comfortable and uniform temperature throughout the house. Although untraceable on utility bill statements, I believe this was a major factor when comparing before and after energy consumption calculations."
"This rebound trend is not new. For example, a rebound effect was also noticed when air bags were first installed in passenger cars; people actually got in more accidents, and injuries increased because many people drove more recklessly believing they were super-protected. I can imagine the occupants' conversation during their first winter: "Honey I'm cold. Since our new furnace is so efficient, I'm going to crank up the heat and enjoy our high efficiency new toy. Who needs these wool socks anymore!" I believe the behavior of the occupants was a significant contributor to the energy used, even with the equipment upgrades," said Revers. "Good job Kevin, you nailed it."
This Month's Stumper:
Thanks to Kebbyn Giffin, a home performance trainer at SUNY Canton in New York State, for this month’s stumper! The two-story house with attached garage was newly built, one in a row of houses all the same, that appeared to comply with code. Yet it didn't pass the building airflow standard. The blower door test revealed that the band joist area between the first and second floors, which by rights should have been inside the house, was directly connected to the outdoors. Kebbyn removed the siding of the band joist and found no sign of any problem there. Looking into the attic above the heated garage revealed a partitioned wall between the garage attic and the house with plywood sheathing going down below blown-in insulation. What was causing the air leakage?
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