Improve comfort and energy efficiency with internal wall insulation in London. Learn how it works, its key benefits, and why it suits many solid-wall homes. What Is Internal Wall Insulation? Keeping a London home warm can be difficult, especially in older properties with solid walls. Heat can escape through poorly insulated walls, making rooms feel cold and increasing the need for heating. Internal Wall Insulation London is a practical way to improve thermal performance by adding an insulating layer to the inside of external walls. Unlike external insulation, this method does not change the outside appearance of your property. Therefore, it can be a useful option for homes where changing the exterior is not suitable or desirable.