A large percentage of houses in Enright Ridge Urban Ecovillage have been well insulated. Jerry Ropp, who has been our contractor for 19 buildings has insulated these houses as well as another 20 houses himself.
Almost all the houses that we have insulated had a few inches of rockwool (a type of insulation) in their ceilings, but not near enough. The walls are almost never insulated. We blow in cellulose insulation into most ceilings and wall cavities. We put in over 50R in the ceilings and with most wall caveties being 4 inches, we can put in between 16 to 20R in the walls. If we put in a new wall we will usually use fiberglass insulation. We may also put in some rigid board insulation. We attempt to make buildings as energy-efficient as we can.
The issue with most of these insulations is what happens to them if a house is torn down. Many of them will not decompose easily. We blow in insulation in most of the houses, and cellulose is the best for this purpose. It is made of paper. Chemicals are put on it to make it fire resistant. They should breakdown more easily than most insulation. There are some biodegradable insulations that can be used instead of fiberglass. We have used it at times, but it is quite expensive at this time.
Making older homes energy efficient should be a high priority of any home owner. (There are requirements for insulation of most new homes.) It saves an amazing amount of energy and also makes the home more soundproof. It is an excellent investment!