Both can be true. A well-insulated houses loses maybe 0.2W/K/m^2 whereas an unimproved building from the 50s is easily 2W/K/m^2, so that's an order of magnitude

Both can be true. A well-insulated houses loses maybe 0.2W/K/m^2 whereas an unimproved building from the 50s is easily 2W/K/m^2, so that's an order of magnitude difference. By comparison, keeping your house warmer by one or two degrees Celcius will add 5 or 10% to your heating bill. The same is true for many other rebound effects, such as the change from filament light bulbs to LED lighting: yup, people do use more lighting more of the time, but not nearly enough to offset the energy savings from the new technology.