Usually means you need more insulation in the wall. 

Also, inside could need updated plumbing and electrical (also possible asbestos insulation).

After home inspection, the condition is not that good but acceptable, has Asbestos problem, missing insulation on the roof, couple of pipes need to be replace and also water heater tank, the basement has bathroom but no permit.

Missing insulation under the roof, minor roof damage, A/C temperature difference in half the house, no cable hookups anywhere in the house, doors not up to pool code, and a few other minor things.

Some have home age and insulation and wind resistance requirements too.

During development, I can get in there and increase efficiency by replacing furnaces, water tanks, better insulation, better doors and windows, etc.

Between writing down their land and keeping deposits on all the promised homes, they have insulated themselves quite a bit.

They are not one and the same and they were built to have that insulation.

Horsehair plaster, poor insulation, crappy windows, 2×4 sidewalls... 

I've looked at houses near downtown (older houses built in the 1950-1970's) and have a friend who owns a rental down in the Beverly Green area and his bill is much higher due to the external ducting and poor insulation of those types of houses.