Solid walls lose even more heat than cavity walls; the only way to reduce this heat loss is to insulate them on the inside or the outside.
This will help create a more even temperature in your home, help prevent condensation on the walls and ceilings and can also reduce the amount of heat building up inside your home during summer hot spells. It's not cheap, but you will soon see the benefits to your heating bill and it's another way of playing your part in reducing CO2 emissions. There are two types of solid wall insulation: external and internal.
This involves adding a decorative weather-proof insulating treatment to the outside of your wall. The thickness of the insulation needs to be between 50 and 100mm and is usually installed where there are severe heating problems or the exterior of the building requires some form of other repair work providing the opportunity of adding insulation.
Solid walls can also be insulated by applying internal wall insulation. Types include ready made insulation/plaster board laminates or wooden battens in-filled with insulation or flexible linings.
Insulation/plaster board laminates usually consist of plasterboard backed with insulating material typically to a total thickness of up to 90mm.
For more on how solid wall insulation works, costs, savings and other considerations see the Energy Saving Trust information page.