Traditional buildings are more energy-efficient than previously thought, according to recent research.
Dr Caroline Rye from the University of Portsmouth carried out research on the energy efficiency of old buildings for the Society for the Protection of Ancient Buildings (SPAB).
Jonathan Garlick, technical officer and project leader at SPAB, said: "We discovered that 79% of traditional buildings were more efficient than we thought.
"The U-value system was designed for modern materials and has been wrongly applied to traditional buildings.
"People are over insulating their homes when they don't need to. These old materials work, so if it's not broken, don't fix it. There are pressures from the green agenda about insulation which are fine for modern buildings that are designed to let nothing in."
Garlick also said older buildings have materials that absorb damp and then allow it to evaporate. This research shows that materials such as cob, stone and timber should not be assessed in the same way as concrete, modern brick and breeze blocks.