Sheep’s wool insulation is cool! To be precise it is brilliant at helping to keep a house cool in summer. It knocks the socks off many man-made materials in this regard and achieves it in a number of clever ways.

High Specific Heat Capacity: Wool can absorb a LOT of heat energy before its temperature rises. That means it slows down heat entering the building, keeping indoor spaces cooler for longer.

Decrement Delay (Thermal Lag): Wool naturally resists rapid temperature change. It delays heat transfer so that the hottest part of the day is absorbed, and released later—often at night, when it's cooler and windows can be opened.

Thermal Mass Benefits: While not a traditional thermal mass material like stone, wool mimics some of its benefits—buffering heat and helping to regulate internal temperatures in lightweight construction.

And as a bonus  Moisture + Heat Synergy: Wool can hold up to 33% of its weight in moisture without feeling wet. This adds another layer of thermal comfort by buffering humidity and absorbing latent heat.

These abilities in an insulation material are increasingly important. According to a report on Climate Adaption Pathways funded by UKRI, our homes are going to heat up fast in summer over the next few years so we will all be spending many more hours in uncomfortably hot houses. The worst performing houses for increased temperatures? Those built since 1990. The worst performing houses for increased relative humidity? Older solid wall buildings. Sheep’s wool insulation can help manage both.
How cool is that! An insulation good for heat.