My Undersized Ducted Mini-Split Heat Pump

As part of ongoing energy-related improvements to a recently purchased 1961 Atlanta-area ranch house, Allison Bailes replaced the home’s existing conventional HVAC system with a new Mitsubishi heat-pump system. As you might expect from a guy who has a Ph.D. in physics and who is a bona fide building scientist, Bailes used Manual J to determine the home’s heating and cooling loads. He describes in detail the process and the factors that he used to make certain choices about the inputs he made the calculations with. And then, as he explains in this recent Energy Vanguard blog post, he purposely undersized the system. With a year’s worth of data to support his conclusions about the results of his decisions, this is an interesting case study.