The construction industry is experiencing a significant shift towards sustainable building practices, driven by climate targets, evolving building regulations, and growing awareness of embodied carbon. Natural insulation materials and traditional building techniques are increasingly seen as preferred alternatives to modern man-made products, offering superior performance characteristics alongside environmental benefits. Industry bodies including the Alliance for Sustainable Building Products (ASBP), the Society for the Protection of Ancient Buildings (SPAB), the Institute of Historic Building Conservation (IHBC), Historic England, and the Green Register are championing these materials as essential components of both new build projects and sympathetic renovations.
The Rise of Natural Insulation Materials
Natural insulation materials represent a fundamental departure from petroleum-based alternatives, offering comparable thermal performance whilst delivering additional benefits that synthetic materials cannot match. Three notable natural insulation materials gaining traction in modern construction - cork board, wood fibre board, and sheep's wool - each bring distinct advantages to building projects.
Cork board insulation such as that manufactured by Amorim and Secil, is harvested from the bark of cork oak trees without harming the tree itself, and provides exceptional thermal and acoustic properties. With thermal conductivity values ranging from 0.037 to 0.043 W/mK, cork matches the performance of many conventional insulation materials whilst offering natural fire resistance and moisture regulation properties. The ASBP highlights cork's longevity, with properly installed cork insulation lasting the lifetime of a building without degradation - a stark contrast to synthetic alternatives that may require replacement within decades. There are also no additives in the manufacturing process - when cork is heated to form the boards cork resin is released acting as a natural binder.
Wood fibre board insulation, manufactured from wood processing waste and sustainably sourced timber, delivers thermal conductivity values between 0.038 and 0.045 W/mK. Beyond thermal performance, wood fibre provides excellent acoustic insulation and acts as a thermal mass, helping to regulate internal temperatures. The material's breathability allows moisture to pass through whilst maintaining insulation properties, reducing the risk of interstitial condensation that can compromise building fabric integrity.
Sheep's wool insulation utilises the natural properties of wool fibres to create an effective thermal barrier with conductivity values of approximately 0.035 to 0.040 W/mK. Wool's hygroscopic nature allows it to absorb and release moisture without losing insulation properties, whilst its natural structure creates air pockets that enhance thermal performance. Additionally, wool insulation products like SheepWool Optimal are treated with a biocide-free process to protect them from infestation, thus allowing them to be used and stored indefinitely.
Wood Wool Board
Wood wool board, an alternative to plasterboard, combines wood fibres with mineral binders to create a versatile building material that serves both structural and insulative functions. With thermal conductivity values around 0.09 to 0.12 W/mK, wood wool board provides moderate insulation whilst offering structural strength, making it suitable as a render carrier board, both internally and externally.
The material's open structure provides excellent acoustic properties and fire resistance, with many products achieving Class A1 or A2 fire ratings. Wood wool board's compatibility with lime-based systems makes it particularly valuable in renovation projects where breathability and historical authenticity are priorities. Historic England recognises wood wool board from companies like Soprema and Savolit as a compatible material for heritage applications, noting its ability to improve thermal performance whilst maintaining the permeability essential for historic building fabric health.
Lime Render and Plaster
Lime-based render and plaster systems represent centuries of proven performance, offering construction projects the benefits of breathability, flexibility, and natural antimicrobial properties. Hot lime mortars and hydraulic lime systems provide varying degrees of set strength whilst maintaining the permeability essential for building fabric health.
The carbonation process of lime creates a self-healing mechanism, allowing minor cracks to seal naturally through reaction with atmospheric carbon dioxide. This property extends lifespan and reduces maintenance requirements compared to cement-based alternatives. Lime's alkaline nature (high pH) creates an inhospitable environment for bacteria and mould growth, contributing to healthier internal environments.
In renovation contexts, lime based products are often the only appropriate choice for historic buildings. The SPAB advocates for lime use in conservation work, noting its compatibility with traditional building materials and its ability to accommodate structural movement without failure. The IHBC supports this position through its professional guidance, emphasising that lime mortars allow historic masonry to function as originally designed whilst meeting modern performance requirements. Historic England's technical advice notes consistently recommend lime-based systems for heritage applications, recognising their crucial role in maintaining building authenticity whilst achieving necessary improvements in thermal efficiency.
Benefits in New Build Applications
New build projects incorporating natural materials benefit from reduced embodied carbon, improved indoor air quality, and enhanced thermal performance characteristics. The ASBP's embodied carbon assessments demonstrate significant carbon savings when natural insulation materials replace synthetic alternatives, contributing to whole-life carbon reduction targets increasingly demanded by building regulations and sustainability frameworks.
Natural materials' breathability reduces reliance on mechanical ventilation systems and lowers energy consumption. The thermal mass properties of materials like wood fibre board help moderate internal temperatures, reducing heating and cooling demands throughout the building's operational life. And sheep wool is able to purify the air in a room within a very short space of time, removing many odours and harmful substances.
During construction there are reduced health and safety risks, with natural materials producing minimal dust and containing no harmful chemicals. Installation techniques often require less specialised equipment and training compared to synthetic alternatives, making them accessible to a broader range of contractors and self-builders.
Traditional building techniques have therefore informed modern applications of natural materials, demonstrating how centuries-old principles can enhance contemporary construction performance whilst reducing environmental impact.
Renovation Project Advantages
Renovation projects, particularly those involving historic buildings, benefit significantly from natural materials' compatibility with existing building fabric. The Green Register emphasises the importance of maintaining building breathability in renovation work, noting that natural insulation materials allow historic buildings to function as originally intended whilst improving thermal performance to meet modern standards.
Natural materials accommodate structural movement and seasonal variations without failure, essential characteristics in older buildings that may experience greater movement than modern construction. Their reversibility allows future interventions without permanent alteration to historic fabric, aligning with conservation best practices.
The hygroscopic properties of materials like sheep's wool and lime plaster help regulate internal humidity levels, addressing common issues in renovated buildings where improved airtightness can lead to condensation problems. This moisture management capability is particularly valuable when upgrading traditional buildings that were designed to breathe naturally.
Market Development and Professional Support
Industry support for natural building materials continues to strengthen, with organisations like the ASBP providing technical guidance and performance data to support specifiers' decisions. Training programmes delivered through the Green Register, IHBC, and similar bodies are increasing installer competency and confidence in natural material applications, addressing one of the key barriers to wider adoption. Manufacturers, such as Saint-Astier, Steico and Secil, are also acting as innovators and are contributing significantly in this area.
Professional networks are developing around natural building materials, with specialist contractors, architects, and building surveyors gaining expertise in their application. Historic England's research programmes contribute valuable performance data and case studies, whilst the IHBC's continuing professional development framework ensures conservation professionals maintain current knowledge of appropriate materials and techniques.
Government initiatives supporting carbon reduction in construction are creating market conditions favourable to natural materials adoption. Updated building regulations emphasising whole-life carbon assessment further support the business case for natural alternatives, whilst planning policies increasingly recognise the importance of sustainable construction approaches that respect heritage constraints.
In Summary
Natural building materials offer compelling advantages for both new build and renovation projects in modern construction. Their environmental benefits, performance characteristics, and alignment with regulatory trends position them as essential components of sustainable construction practice. The combined expertise of various industry bodies comprehensive support for their adoption, from technical guidance through to professional training and conservation ethics.
The growing recognition that traditional building techniques and materials can inform sustainable modern construction represents a significant opportunity for the industry. As climate targets become more demanding and heritage conservation requirements more sophisticated, natural building materials provide proven solutions that respect both environmental and cultural heritage whilst delivering superior performance characteristics supported by centuries of successful application.
References & Further Reading
Alliance for Sustainable Building Products (ASBP). Technical guidance on natural insulation materials and embodied carbon assessments. www.asbp.org.uk
Society for the Protection of Ancient Buildings (SPAB). Conservation guidance on lime mortars and traditional building materials. www.spab.org.uk
Institute of Historic Building Conservation (IHBC). Professional standards and guidance for heritage conservation practice. www.ihbc.org.uk
Historic England. Technical advice notes on conservation, energy efficiency, and traditional building materials. https://historicengland.org.uk/
Green Register. Professional training resources and technical specifications for natural building materials. www.greenregister.org.uk
Building Research Establishment (BRE). Thermal conductivity values and performance data for natural insulation materials. https://bregroup.com/
Construction Industry Research and Information Association (CIRIA). Guidance on breathable wall construction and moisture management. https://www.ciria.org/