Isolena Optimal is a medium density product (18kg/m3) and has a thermal conductivity of 0.037 W/m2k. Sheepwool insulation is suitable for all applications, walls, rafters, ceilings and floors. They are available in 50mm, 75mm, 100mm and 140mm, pre-cut to 380mm and 570mm wide.
100% Pure Wool with full Ionic Protect.
Ionic Protect is a new biocide free wool protection system and EAD/CUAP tested. Ecological, sustainable and durability proven.
The innovative wool protection process video
Sheep Wool Sustainability
Wool is a naturally occurring fibre, which means it is a renewable raw material and can be a sustainable choice when responsibly sourced. In lifecycle assessments, emissions are often measured across stages such as A1–A3 (covering raw material supply, transport, and manufacturing). It is also durable and adaptable at end of life: it can often be reused as insulation, recycled into other products, or biodegraded under suitable conditions
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| High Performance | Optimal is a highly effective insulation roll with a superior thermal performance over almost all natural and man-made fibre insulation products. |
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| Safe & Healthy | Optimal is a safe material, not only to handle and install, but to have within your home. |
| Environmental Benefits | Sheepwool Insulation products have unrivalled environmental credentials, making it them the “greenest” choice of any insulation product on the market. Sheep wool is a naturally occurring fibre, so it is a renewable and sustainable source of raw material. Wool has zero global warming potential and is carbon neutral, so choosing Premium means your insulation will have no environmental impact. Sheepwool Insulation also requires only a fraction of the energy to produce in comparison to other insulation materials. At the end of its useful life, Premium can be reused as insulation, recycled into other wool products or buried where it will eventually biodegrade. |
| Value | Optimal is initially a higher cost product than most common insulation types. |
| Width | 380, 570 |
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| Size | 50, 75, 100, 140 |
FAQs
What is ISOLENA sheep wool insulation made from?
ISOLENA Optimal is made from 100% pure sheep’s wool, with no synthetic fibres or additives. It uses a natural protection treatment (Ionic Protect®) and is fully renewable, recyclable and environmentally friendly.
What is SHEEPWOOL OPTIMAL insulation used?
Sheep wool insulation is highly versatile and can be used for:
• Roof insulation (between rafters)
• External and internal wall insulation (between timbers)
• Floor and ceiling insulation (between Joist)
• Loft Insulation (between & over joists)
• Partition walls and acoustic upgrades
It provides both thermal and sound insulation in one product, making it ideal for residential and retrofit projects.
Is SHEEPWOOL OPTIMAL insulation breathable?
Yes. Sheep wool insulation is fully breathable (vapour open) with a vapour resistance factor of around µ = 1.
This means it allows moisture to pass through the structure, helping to reduce condensation risk and supporting healthy indoor air quality.
Does SHEEPWOOL OPTIMAL insulation help with soundproofing?
Yes, sheep wool insulation provides excellent acoustic performance.
• Weighted sound absorption coefficient (αw): 0.75
This makes it highly effective for:
• Reducing airborne noise between rooms
• Improving acoustic comfort in floors and ceilings
• Absorbing echo and reverberation within internal spaces
What is the thermal performance of SHEEPWOOL OPTIMAL insulation?
ISOLENA Optimal has a thermal conductivity of:
• 0.037 W/mK (λD)
This provides strong thermal performance while also offering additional benefits such as moisture regulation and heat buffering.
Does SHEEPWOOL OPTIMAL insulation regulate moisture?
Yes, one of its key advantages is moisture buffering.
Sheep wool can:
• Absorb and release moisture naturally
• Help stabilise indoor humidity
• Reduce the risk of condensation
This makes it particularly suitable for heritage buildings and vapour-open constructions.
Is SHEEPWOOL OPTIMAL insulation safe and non-toxic?
Yes. ISOLENA Optimal:
• Contains no harmful chemicals or borates
• Is safe to handle without specialist protective equipment
• Does not release harmful fibres into the air
It is a great choice for those looking for a natural and healthy insulation material.
Is SHEEPWOOL OPTIMAL insulation resistant to mould and pests?
Yes. The product achieves:
• Mould growth rating: 0 (no growth)
• Resistance to insect pests: Class 0
This ensures long-term durability when installed correctly.
What thicknesses is SHEEPWOOL OPTIMAL available in?
ISOLENA Optimal is available in a wide range of thicknesses, including:
• 50, 75, 100 & 140mm
• Various roll widths – 380 & 570mm
Custom sizes may also be available on request.
Is SHEEPWOOL OPTIMAL insulation environmentally friendly?
Yes, it is one of the most sustainable insulation options available:
• Renewable natural material
• Fully recyclable
• NaturePlus certified eco product
It is ideal for low-carbon and environmentally conscious building projects.
Does SHEEPWOOL insulation really purify indoor air?
Sheep wool insulation can help improve indoor air quality by naturally absorbing and binding certain airborne pollutants. The wool fibres contain keratin, which has the ability to react with and lock away substances such as formaldehyde commonly found in indoor environments.
Sheep wool also regulates humidity by absorbing and releasing moisture, helping to maintain a more balanced internal environment, which not only contributes to overall air quality and comfort, but also helps prevent the high and low humidity levels in which mould and other harmful organisms thrive.
While it should not be considered a replacement for ventilation, sheep wool insulation can play a supporting role in creating a healthier indoor environment when used as part of a breathable building system.
Is Sheep wool insulation without plastic better?
Sheep wool insulation that does not contain plastic is generally considered a more natural and sustainable option.
This supports the performance of breathable building systems, particularly in solid wall, timber frame, and heritage properties where moisture management is critical.
Plastic-free sheep wool insulation also aligns more closely with sustainable construction principles, offering a lower environmental impact and maintaining the natural characteristics of the material.
Are sheep harmed in the production of sheep wool insulation?
No. Sheep wool insulation is made using wool that is shorn from sheep as part of their normal annual care. Shearing is essential for animal welfare, helping to keep sheep clean, healthy, and comfortable, particularly in warmer months.
The wool used for insulation is typically a by-product of the agricultural industry, meaning it makes use of a natural material that would otherwise have limited value.
When responsibly sourced, sheep wool insulation provides a sustainable and ethical way to use a renewable resource without harm to the animals.
How much moisture can sheep wool insulation absorb?
Sheep wool insulation can absorb up to 33% of its own weight in moisture without losing its thermal performance.
This helps regulate humidity within the building and reduces the risk of condensation.
How long does sheep wool insulation last?
Sheep wool insulation is extremely durable. While it carries a declared service life of 50 years, real-world performance is likely to exceed this considerably when installed within a well-designed, vapour-open building fabric.
Can sheep wool insulation be reused or recycled?
Yes. At end of life, sheep wool insulation can be:
• Reused if carefully removed
• Recycled into other wool-based products
• Composted and used as a natural fertiliser
• This supports a circular building approach.
How is sheep wool insulation produced?
The production process involves:
• Washing raw wool using water and natural processes
• Mechanically forming fibres without synthetic binders
• Using Ionic Protect® treatment for durability
This ensures a natural, low-impact manufacturing process.
Where does the sheep wool come from?
The wool used within ISOLENA brand products is sourced from European sheep farming, primarily as a by-product of agriculture.
This supports local supply chains and reduces environmental impact.
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