Also, today Lifehacker via Low-tech Magazine reposted a short article about the merits of adding layers of insulation to your body instead of overly heating or adding insulation to your dwelling. I can confirm that putting on layers does in fact keep you warmer. I can also confirm that 55 degrees F indoors is not particularly enjoyable and I’d rather have a better insulated dwelling instead of wearing my belay jacket indoors at all hours of the day.
Also, while I appreciate the sentiment of “put on a sweater” or “put on more layers” as the differential between the outdoor and the indoor temperature increases, air leaks become even more noticeable. When it was 8 degrees F outside one night the draft inside our 100 year old home, whether running the gas heat or not, was incredible. Now that the weather has warmed up the indoor temperature is much more stable and the draft is significantly less noticeable.
There are lots of pages online about “sensible“, “latent” and “convective” heat and cooling loads. I found a nice page from Dr. Chan in Hong Kong, he has pages on both cooling and heating calculations.