It's partly materials, but there are lots of factors: - building codes raising the bar, which has brought down costs for what used to be "fancy" materials - i

It's partly materials, but there are lots of factors: - building codes raising the bar, which has brought down costs for what used to be "fancy" materials - improvements in building science - increased energy costs driving demand for improved efficiency - greater awareness of energy consumption amongst the population I've renovated a few houses build in the 60's and 70's in Canada. As far as I can tell, they had the materials and knowledge to make far more efficient houses, but much of the time, it was just easier, quicker and cheaper to install a big-ol' heater and drive the cold out. With a few simple and relatively cheap building envelope modifications and a more efficient heat source, it wasn't difficult to bring heating costs down by 50% or more.