This is a reprint of a recent article on some studies done to show that the straight R-value of solid wood is misleading. Even though it seems worse than other materials, because wood has a lot of mass it actually can store energy, not just prevent the ingress ( or egress) of energy, which is only what R-values measure.

Wood insulation properties studied

Lincoln University researchers have studied the paradox of houses built from solid wood seeming to have greater levels of heat retention and coziness than the insulation value of the wood wall itself would suggest. On their own, solid wooden walls have a fairly low R-value – meaning that theoretically the walls should not provide a particularly high level of thermal insulation.

“But the R-value is just a measure of the material’s resistance to heat flow,” Research Engineer Dr Bellamy said. “It only says how much heat is passing through, not how much is being stored.” Researchers discovered the answer to this puzzle was wood’s superior thermal mass. Having worked extensively with the concrete industry where concrete’s ability to store heat is well known, Dr Bellamy was not expecting wood to provide as much thermal benefit as it does.