Taking note of use
I grew up in a snowbelt of Northern Michigan in the 1990s. I had this strange dichotomy of identity -- both rustic and refined, somehow. Traverse City is a very popular tourist destination, and as such, had a number of things that are close to urban-istic; and on the same token, I lived and worked in environments that demanded care and understanding to prevent a car from becoming inoperable several miles away from anyone that can help. But that "rustic" aspect taught a person that they should have various resources on hand, just in case, and that easily translated into making choices about everything from clothing to vehicles to home improvements based on the "just in case" situation. It was better to have waterproof boots as your main footwear just in case the weather turned terrible and the parking lot was full of slushy snow. It was better to drive a vehicle with good clearance and four-wheel drive just in case a blizzard hit and you suddenly had to drive through feet of snow on your way home.
So when I purchased a small commuter vehicle in my 30s while living in Chicago, I was nervous when it was sold with only summer tires on it. I figured that I would have to buy a set of all-season tires for it sooner or later, but procrastination got the better of me as I continually didn't need those all-season tires day after day. When it rained, the tires performed well enough. When it snowed, the salt trucks were usually out in force causing most or all of it to melt into water.
But sometimes, it would snow a lot. I remember driving a co-worker home to our shared neighborhood during such a snowstorm. The artery roads were clear, for the most part; the expressway was clear; but when we turned into our side-streets, I had to drive carefully to keep the car from getting stuck while also going slow enough to avoid colliding into anyone as we passed through the intersections. It was treacherous, but also very low-speed. A collision would have been damaging to the cars, but not really to the people inside. But as we made the final turn on our street, I felt the weight of that moment lift off my shoulders -- we had made it safely, in a terrible snow storm, on summer tires, in a light-weight commuter car.
I didn't have to think about the consequences of those tires again for several months. And as the years passed by, I learned that there were usually a few days a year when summer tires on a light commuter car were a terrible idea. I'm fortunate enough to live in an urban area, so on those days, I could choose to take different transportation to work. As a result, I never got those all-season tires for as long as I owned that car. On the days when it was incredibly snowy, I drove slowly and carefully. It wasn't fun, and often was stressful. But I made it work well enough. And the other 362 days, I didn't even notice it.
No one solution is right for all people in all situations, and a different person would rather drive on luggy snow tires during the summer because filling a car with gasoline is easier than changing out tires. Then, when the snow flies, they don't have to think about grip and control. Other people don't have the option of a slow drive for a few miles to get home. The solution of a light-weight commuter car with summer tires isn't rational, so they shouldn't do it.
And even though I now live in a Northern City, complete with bitter-cold temperatures and snowstorms, I started to notice that the _actual use_ didn't justify the purchase and hassle of swapping out types of tires. If I talked to a tire salesperson, they would undoubtedly look at me like I was an idiot if I said, "I think I'll just go around on summer tires all year 'round." However, they would only be right -- I would be an idiot -- about three days a year: 0.8% of the days of the year. That ratio isn't enough to convince me.
Bringing it to air source heat pumps, I first started learning about the technology several years ago. At the time, I knew that nearly all manufacturers of air source heat pumps designed them for temperate climates, which Chicago is not, but the people I was listening to were saying something similar, over and over again. That was changing. Certain manufacturers were designing "cold-climate" air source heat pumps, and the old adage that heat pumps couldn't work in Northern Cities would quickly become misguided.
Then I combined this sneak peek into the future of heat pumps with my tendency to examine actual use. I began to wonder how the process of heating my home actually worked, from a mathematical position. The more I learned, the more I realized that there is no magic conversion that happens when heating a house. The amount of energy you put in is the amount of energy you radiate out. The difference in the temperature inside the house versus outside the house impacts how quickly that energy radiates out. The number of isolated air pockets you place between the inside of the house and the outside of the house slows that radiation down, but doesn't stop it. But there were aspects that I didn't yet understand: a furnace produces a tremendous amount of heat right away, and perhaps the "speed" of that heat production matters. Maybe a heat pump could theoretically produce the needed heat, but not be able to deliver it with enough speed to have it matter -- maybe it would all escape before it got to the rooms. Or maybe it would be able to create enough heat, but again because it was more "tepid" than "hot", parts of rooms would feel icy cold.
But I had a sneaking suspicion as I talked to more people about this and kept hearing the same thing over and over again: the conversation was governed by the notion of "well, at least you'll have it if you need it." It was the "just in case" situation, but something felt off to me. Winters would get bitter cold sometimes, but often it would be rather mild. And that was only for a few months a year with the rest of the time being either temperate or hot. I suspected that my furnace might be the equivalent of the luggy snow tires for my car, and that it was completely overkill (and perhaps even wasteful).
To be sure, I decided to collect some data. Two years' worth of data.