10 air changes per hour is a lot; I believe the current recommendations for average climates is 3. And we're looking at the margins; 1 air change per hour can

10 air changes per hour is a lot; I believe the current recommendations for average climates is 3. And we're looking at the margins; 1 air change per hour can do wonders for preventing the spread of disease and improving air quality, compared to 0 air changes per hour. Nevertheless, I redid your math, and found that your hypothetical home has 26,728 more BTUs of energy in its air, compared to the outside air[-1][0][1], and that the recommended furnace for such a climate should be 160,000 BTU/hr [2]. Using those numbers as a base, I find that, with an efficiency of 95%, it would require 120 (that's one hundred and twenty) air changes per hour to double heating costs. With 60% efficiency, it would require 15 air changes per hour to double heating costs. And it only takes a few air changes per hour to increase comfort and prevent illness. [-1] I suddenly realized that the google search links that I used for these calculations are messy and unwieldy, so I'll summarize my calculations: (2600 ft^2) * (8 ft) represent the volume of the house; (1.225 kg / m^3) represents the density of air, (1.005 kJ/(kg * Kelvin)) represents the specific heat of air, (70 * (5/9)) represents the temperature difference you gave me, in Kelvin. Multiplying everything together, and letting Google automatically take care of unit conversions, gives me 28.2 MegaJoules of energy in the house. [0] https://www.google.com/search?q=%282600+ft%5E2%29*%288+ft%29*%281.225+kg+%2F+m%5E3%29*+%281.005+kJ%2F%28kg*Kelvin%29%29+*+%2870*5%2F9*Kelvin%29&sxsrf=ALeKk03mIEqnojDLPEsUQ6UUDvN1Z4JDBQ%3A1620993932615&ei=jGeeYKjqJMH5-gSToaPgCQ&oq=%282600+ft%5E2%29*%288+ft%29*%281.225+kg+%2F+m%5E3%29*+%281.005+kJ%2F%28kg*Kelvin%29%29+*+%2870*5%2F9*Kelvin%29&gs_lcp=Cgdnd3Mtd2l6EAM6BwgAEEcQsANQjoYCWI6GAmCejQJoAHAGeACAAYkBiAGJAZIBAzAuMZgBAaABAaoBB2d3cy13aXrIAQjAAQE&sclient=gws-wiz&ved=0ahUKEwio4KT8kMnwAhXBvJ4KHZPQCJwQ4dUDCA4&uact=5 https://www.google.com/search?q=%282600+ft%5E2%29*%288+ft%29... [1] https://www.google.com/search?q=convert+28199142.9+joules+to+BTU&sxsrf=ALeKk01pPJuq_5rY_j_959mWo5IeabgJIQ%3A1620993993789&ei=yWeeYKHRL833-gS14Yh4&oq=convert+28199142.9+joules+to+BTU&gs_lcp=Cgdnd3Mtd2l6EAMyBQgAEM0CMgUIABDNAjoHCAAQRxCwAzoECCMQJ1CwH1ihR2CwS2gCcAJ4AIAB-AGIAeYLkgEFMC40LjSYAQCgAQGqAQdnd3Mtd2l6yAEIwAEB&sclient=gws-wiz&ved=0ahUKEwjh2bqZkcnwAhXNu54KHbUwAg8Q4dUDCA4&uact=5 https://www.google.com/search?q=convert+28199142.9+joules+to... [2] https://www.pickhvac.com/calculator/heating-btu/ https://www.pickhvac.com/calculator/heating-btu/