Sheep’s wool is popular among outdoors people for good reason. It retains good insulating properties even when moist while being breathable. It is naturally fire resistant, which is a bonus both in construction and around the campfire. Due to its ability to resist high heat it can be used to insulate heating pipes. It can also be used as thermal insulation of walls and ceilings, or as strips for stopping draughts around doors and windows. If compressed it works well as a sound dampening material.
Thermal performance and climate impact
Sheep’s wool has a thermal conductivity of approximately 0.034-0.045 W/mK. This makes it on par with mineral wool and EPS-products. In its natural state it is sensitive to moths and is therefore treated to repel them. A great benefit of the material is that it does not cause the same irritation of the skin as mineral wool. Some products are even recommended to fit to size by simply ripping the material by hand. Another benefit is the low C02-emissions from the production of the material. Per kg of material sheep’s wool emits only approximately 1/10 of the C02 of mineral wool and 1/20 that of EPS or XPS. These values can differ depending on where the materials are produced. A large environmental benefit for sheep’s wool is that it is compostable at the end of its lifespan, as opposed to mineral wool which is designated as non-recyclable and destined for landfill.
Moisture performance and indoor air quality
Sheep’s wool is hygroscopic, meaning that it can absorb and release moisture. This gives the material the ability to help regulate the moisture levels indoors. If the air is moist the material will absorb moisture from the air and if the air is dry, it will release it. The materials ability to release moisture prevents moisture buildup and makes the wool naturally resistant to mould growth. It is claimed that wool can improve indoor air quality, however, insulation material in general is sealed into the walls and ceilings behind drywall which reduces the contact between the indoor air and the wool. In modern construction a vapour barrier is often present between the interior drywall and the insulation, meaning that there would be little to no air exchange between the wool and the room air.
Additional uses
In the garden wool can be used as blankets to protect plants against the frost. Unwashed sheep’s wool can be hung in the garden where it works as a deterrent to deer and rabbits. These animals does not appreciate sheep and usually want to keep a distance if they smell them. Wool can also be placed on the ground to reduce evaporation and keep weeds down. Being compostable, the wool can be dug into the soil as it will naturally decompose and add nutrients back into the soil. Of course it can also help to keep the gardener warm. As a warming insole wool helps to keep the gardeners’ feet nice and cosy inside his or her boots.
Summary
To summarize, sheep’s wool is a very eco-friendly alternative to traditional insulation in construction offering advantages such as fire and mould resistance. It offers good thermal insulation and is pleasant to work. It is a renewable, low impact and biodegradable option for both clothes, housing construction and garden use.