Sheep Wool Insulation: the carbon smart solution

Sheep wool insulation is no longer overlooked as an eccentric solution in the building industry. Its popularity follows an increased awareness in the public and in the construction industry on the health benefits and performances of natural fiber insulation.     

The main focus regarding insulation was primarily on thermal, acoustic or fire resistance without much consideration given to the material being used outside that frame. 

Nowadays, new buildings have to follow stricter regulations than ever before, resulting in more efficiently insulated buildings. The focus on creating intelligent buildings and airtight structure brings new challenges and means the industry had to find new solutions to tackle water vapour control (AKA moisture management).

Given so much time spent indoors, indoor air quality has become an important factor in today’s design. Especially when studies from the scientific community are suggesting a link between volatile organic compounds (VOCs) and its negative impact on cognitive abilities. 

That’s where nature comes in with a solution of its own. And one of the unique features of sheep wool is its unmatched breathability.

Indoor Air Quality: a cleaner air

Whether it's in paint or wood, many common household furniture, items and finishes release potentially dangerous levels of chemicals commonly known as VOCs. 

Sheep wool effectively cleans the air by sucking those VOCs out of the air.

The natural protein Wool is made up of various amino acid chains, of which 60% have a reactive side chain. It is those reactive chains that allow the wool to absorb bad smells and harmful chemicals such as Nitrogen Dioxide, Sulphur Dioxide and Formaldehydes

In neutralising those, it effectively purifies the air and delivers obvious health benefits. And not only does it achieve that, but it does it in a short amount of time as well. Experiments by German academics in 1999 have shown that wool removed between 80% and 87% of concentration of formaldehyde in a test chamber. 

Thermal resistance:

From a thermal conductivity angle, wool punch above all the other types of insulation, with only Sprayfoam performing better.

Thermal conductivity measures the transfer of heat from one material to the other. It is measured in W/mK. The lower the value achieved, the better the insulator is.

Sheep wool insulation’s thermal conductivity is between 0.035 - 0.04 W/mk, compare to 0.044 W/mk for typical mineral wool. 

While 200mm of sheep wool will achieve a U-Value of 0.2, it often performs better than that, thanks to its low thermal conductivity coupled with its high moisture management properties.  

Those results are due to the particular crimped nature of wool fibers. Wool fibers are naturally undulated and trap the air in millions of tiny air pockets, which in turn, form a natural thermal barrier. It is so effective that tribes in the west of Africa have been using wool for insulation since the dawn of sheep.

Fire Resistance: Sheep wool does not burn, period!

Due to the high level of moisture (nitrogen), wool simply doesn’t burn. It is naturally flame resistant and self extinguishing. It is basically one of the only fibres that resist fire and will self extinguish once the source of flame is removed. 

Instead of bursting into flame it will smoulder and singe away. You would need to bring the temperature above 560°C to burn it and at the same time, increase the level of oxygen in the air above 25%, since the air contains 21% of oxygen that makes it quite difficult. 

Moisture management : it regulates humidity

What really sets sheep wool apart from the rest of the pack is its breathability. It does a fantastic job in eliminating condensation and moisture from the air without compromising its thermal performance unlike products that use fibreglass.   

It can absorb up to 35% of its weight in moisture without feeling damp. In doing so, wool fibers generate tiny amounts of heat which prevents condensation by keeping the temperature above the dew point.   

This ability to produce heat, act as a buffer against heat change that usually occurs in humid conditions. In practical terms, this means that there is less need to constantly adjust heating and cooling levels. Sheep wool will keep a building cool during the day and warmer during night time. 

Moisture management is achieved thanks again due to the nature of the sheep wool fiber. The core of the fiber is hygroscopic and able to absorb and then expel water vapour. For that reason, it is often used in applications where condensation tends to be higher such a loft space.

Sound Insulation: it reduces airborne sound transfer

If all the above reasons were not enough, then let's move on to the acoustic insulation.   Again when it comes to sound insulation, sheep wool fares way better than all other types of wool materials. This alone explains why schools and offices are turning more and more to sheep wool insulation to keep the peace between their walls.   

The airborne sound transfer is considerably reduced by the multitude of layered wool fibers.

Easy to work with: Sheep Wool doesn’t itch

It is the safest type of insulation to work with, imagine working in a whoolly jumper warehouse and you’ll get the idea. The stuff is harmless. No need to wear protective gear, mask and goggles to install sheep wool unlike when working with mineral wool. 

Which makes it an ideal choice as part of a typical DIY project like insulating a loft.  You can do away with protective clothing as it is chemical free, safe to handle and completely dust-free.

Sustainability

Wool is a resource that has been naturally engineered to save energy. If you are looking at sustainability, all other insulation products pales in comparison. It is sustainable, renewable and recyclable (it can easily be remanufactured or biodegraded). 

As a finished product that consumes less than 15% of the energy involved in producing glass fiber, it will pay back its energy costs more than 5 times sooner versus any man made insulation products (15kW of energy used to produce 1m³).

Not only is it energy efficient, but wool fibers are elastics and do not settle over time, which means it will keep naturally “expanding” and will retain its thickness all the way through the lifespan of the building, thus increasing the insulation efficiency.

 Conclusion

Builders are creatures of habit and are understandably hesitant to specify sheep wool insulation in an already competitive industry. But saving on insulation is a false economy given the health benefits, lifespan and reduction in energy costs that comes with Sheep Wool. It actually pays for itself quicker than any man made alternative. 

Technological innovation and intelligent design have always looked at nature for inspiration, and sheep are currently at the forefront of those innovations.