If your home was built before the 1920s, then it is more than likely that it has solid walls instead of cavities, which mean there will be insufficient protection against heat loss. In fact, you can lose as much as half the heat due to an uninsulated wall in comparison to an insulated one.
Improving the thermal efficiency of solid-wall properties is an area which has massive potential for the future as this is an area where very little work has been done to date. However, more and more individuals are now starting to recognise the advantages of insulating such households and this is an area which is now seeing a real growth with many cost-effective solutions now available.
If you live in a home with solid walls, 45% of your heat is escaping through the walls, which is costing you money. Insulating the walls will dramatically prevent heat loss in the winter.