Adding more insulation, replacing an inefficient furnace, or performing air-sealing measures are oft-recommended strategies for lowering energy consumption and saving money.
Aaron Vander Meulen puts his finger on a key issue, however, when he wonders whether there is a way of determining exactly how much money improvements such as these will save.
“Anecdotally, my parents upgraded to a 95% furnace last year, and are seeing the savings, but it would have to be compared to the [heating degree days] for each year, correct? And even at that it’s something of a crap shoot since they have a gas water heater as well? One would need to monitor volume of gas at the furnace, correct? is there any sensor for this?”
His question points to the complexity of this seemingly simple question and is the subject of this week’s Q&A Spotlight.
Two points of view
The simple answer to your question, says Michael Blasnik, is no.
“There is no way to figure out the exact savings from a retrofit because we don’t have a perfect parallel version of the world handy where everything else was the same except for the retrofit,” he writes.
Blasnik suggests Meulen can get a “fairly good idea” of savings by analyzing energy and weather data, but he adds, “You can’t control for everything in any given home — differences in occupancy, behavior, non-temperature weather (wind, solar gain), and other changes in the building and equipment can all affect the observed savings… By analyzing the energy use of large groups of homes you can learn a lot more about retrofit impacts, but the findings in any one home will always be suspect.”
John Klingel, however, is voting an “emphatic” yes to Meulen’s question.
“Not down to the gnat’s butt, as you…