Traditionally built solid stone walls can be as much as three times better at keeping in the heat than is generally supposed, according to SPAB research.

The Society for the Protection of Ancient Buildings (SPAB) have gone out and measured the heat loss through a variety of traditionally built walls – including walls of limestone, slate and granite – and compared the results with the theoretical values produced by BuildDesk U 3.4 software.

A report based on the study can be downloaded from the SPAB website (see address at the end). Written by Dr Caroline Rye, it says 79% of the traditionally built walls sampled performed as much as three times better than the software predicted they would.

Jonathan Garlick, SPAB Technical Officer and project leader, says: “Amazingly, this research has not been carried out before in England. Accepted theoretical performance figures have long been used as a standard base measurement by professionals and homeowners when old buildings are being up-graded, altered or even assessed for Energy Performance Certificates.

“But are they correct? We believe that with some traditional materials our in-situ results prove that they are not. We appear to be actually underselling the thermal performance of our old buildings by not fully understanding them.”