ASBP Vice-Chair submits written evidence for the Environmental Audit Committee

Sustainable and Breathable Building Products & Systems for Retrofit

Submitted to: Environmental Audit Committee: Inquiry into Energy Efficiency of Existing Homes

Submission by: Mark Lynn BSc. MBA MIEMA C.Env.
Managing Director – Eden Renewable Innovations Ltd (Thermafleece)
Vice-Chair – The Alliance for Sustainable Building Products

Submission date: December 2020

1. Introduction

Sustainable bio-based and breathable products and systems can provide many energy efficient, healthy, and sustainable improvements to existing homes but are to date, under-utilised in the UK despite being well established in other major European countries. Products include insulation made using natural fibres, breathable mineral, clay and lime-based plasters, renders, mortars, and paints as well as structural components made predominantly from timber.

All these products are currently manufactured and used at scale, if not in the UK then elsewhere in the major economies of Europe. They represent a vital piece in the jigsaw of solutions required to upgrade nearly 20m homes over the next decade and beyond.

We have outlined some of the benefits of these products, and the opportunities and challenges faced to make sustainable bio-based and breathable products part of the mix of solutions for improving the energy efficiency, health, and sustainability of existing homes.

2. Benefits

2.1 Sustainability

Bio-based materials such as sheep’s wool or wood sequester non-fossil carbon. As the plant or animal grows, carbon from the atmosphere forms part of their natural fibres locking up nearly 2 kg of CO2 for every kg of natural fibre. Because bio-based building products are durable and long lasting, the CO2e embodied in the material remains locked up and removed from the atmosphere for many decades.

Natural raw materials can be grown locally, regenerate rapidly and can be harvested annually allowing biomass to regrow, continually locking up non-fossil carbon from the atmosphere. In the UK we currently have access to home grown sheep’s wool, timber waste, hemp, and straw, all of which can be used to make insulation.

Lime based renders, plasters and mortars have lower embodied carbon compared to equivalent cementitious materials due to the lower energy inputs during manufacture. Moreover, these lime-based materials reabsorb CO2 at a relatively rapid rate during service compared to cementitious materials due to their higher porosity. This reabsorption of CO2 reduces the embodied carbon of materials such as lime render over the lifetime of the product.

The ASBP believes that product level sustainability should be demonstrated wherever possible through verified Environmental Product Declarations (EPD). Training should be provided to ensure those at the assessor level are able to understand EPD and relative impacts of products to help communicate this to the householder and help with appropriate product choices. The ASBP is producing a series of information sheets aimed at generating a wider understanding and awareness of EPD. Please our Resources section for more information and to download papers.

Consideration should also be given to a simpler form of communication that takes key data from EPD and presents it in a way that householders can understand, work on this is currently underway within the relevant European Standards Committee following a mandate from the European Commission to consider business to consumer communication of EPD. However, we need to be careful that this does not result in information being dumbed down throughout the length of the supply chain. Moreover, a traffic light system will only work if it is broadly accepted and stands up to scrutiny.

The carbon sequestered in bio-based materials used in retrofits should be given a value and this value reflected on the record of the dwelling, for example, including it in EPC’s.

2.2 Breathability

Heat and humidity are inextricably linked. It is well documented that sub-optimal moisture and humidity can have a very detrimental effect on occupants and the condition of the building fabric within dwellings. Poorly considered energy efficiency improvements can compound rather than solve problems associated with excessive damp and humidity. The UK Centre for Moisture in Buildings was founded to research, study and inform on these issues.

Breathability is an often over-looked or poorly understood aspect that can contribute to a healthy humidity balance within the home. Truly breathable materials work by allowing the passage of moisture where required whilst at the same time binding and releasing moisture in balance with internal humidity levels. This allows breathable materials to capture moisture and hold it in a safe form as well as preventing bottle necks that allow the build-up of moisture within the building fabric.

It must be noted that breathable materials are not the sole solution to problems with damp and humidity but are instead a valuable part of the broader remedy not to be ignored or disregarded. Nonetheless, breathable building materials should be at the core of retrofit assessments and plans particularly for older buildings that were not designed with many modern materials in mind. For this to happen greater acceptance and understanding is required.

2.3 Thermal Buffering

A “no regrets” approach to improving thermal performance of dwellings should limit both heat loss and heat gain. Preventing heat loss and reducing the heat energy demands of dwellings is already central to the governments carbon reduction plans.

However, preventing dwellings from over-heating provides additional gains, vital in a situation when every positive intervention counts.

Bio-based insulation and building materials have an optimal thermal mass that enables them to absorb heat at just the right rate to prevent excessive internal heat build-up during the hottest part of the day during warmer months. This helps reduce the demands from energy sapping air-conditioning systems during summer months and creates a vastly healthier temperature balance within the dwelling year- round.

Heat gain is measured by decrement delay. The level of decrement delay should form part of the performance measurements for new build and retrofit and recorded in EPC’s for example.

2.4 Low Pollutant Source & Good Indoor Air Quality (IAQ)

Building materials can be a significant source of volatile organic compounds (VOC’s). VOC’s reduce indoor air quality and have the potential to cause harm. Controlling these pollutants at source should be a key consideration in the choice of materials and systems for retrofit. Excessive damp and humidity give rise to microbial VOC’s (MVOC’s) that contribute to a raft of respiratory and other diseases. Sustainable building products such as NFI’s are a low source of VOC’s and play a crucial role in maintain healthy indoor humidity levels helping control MVOC concentrations within the dwelling.

Greater consideration of indoor air quality should be given at the assessment phase and appropriate measure taken. This includes the selection of low source materials. However, for this to be effective, training on the importance of IAQ is required.

3. Natural Fibre Insulation Market Size and Potential

Natural fibre insulation (NFI) accounts for around 0.2-0.3% of the UK insulation market at contractors’ prices. This covers both new build and retrofit. By contrast, in France and Germany, market penetration is around 5-10%. In the UK, only sheep’s wool insulation is on a par with European economies for market share. For the UK to reach this level, NFI’s need to achieve a sustained CAGR of 20-30% over the next decade and beyond.

Ensuring that all existing properties are upgraded to their full potential requires the most comprehensive mix of products and systems to cover all shapes and sizes of dwelling. NFI’s offer the best solution in many instances so growing supply and demand for NFI’s and complimentary products to a level comparable to our European colleagues is essential.

The current market share for NFI in Germany was achieved by sustaining a CAGR of more than 10% for 15 years albeit from a slightly higher starting point that the UK. This was made possible through the development of commercially competitive building systems, broad education, and the creation of production capacity in expectation of growing demand. All these areas received comprehensive financial support from government to develop and grow. The same needs to happen in the UK.

In Germany and Austria, educating tradesmen, contractors, architects, and students at the earliest stages of their learning were key. Over time, information has been collected and made available in easily understandable formats. This is well illustrated in platforms such as Dataholz. Dataholz is a simple web facility that illustrates a wide range of systems and product combinations for timber frame constructions. It allows people at all levels to explore options and understand systems in a very simple way.

In Germany, the development of cost competitive building systems based on the obvious compatibility of natural timber frame and natural fibre insulation were key. Using natural materials in combination helps maximise the benefits of natural materials previously discussed. In the UK, timber frame construction is all too often insulated using purely man-made materials which seems counter-intuitive. It is worth noting that timber frame construction is used in many retrofit applications and should not just be viewed as a technology limited to new build.

The development of modular or factory formed timber frame solutions has led to the production of high quality, good value solutions. Technologies that could be adapted for retrofit purposes.

4. Supply Chain

Given the enormity of the challenge for us all, the NFI and sustainable products supply chains face the same challenges as other more widely used technologies. Product supply needs to be ramped up to meet future demand, domestic production capacity eventually needs to be created or scaled up and the skills and know-how to assess, plan and execute NFI based retrofits needs to be substantially scaled up. Much of this requires government funding to de-risk capital investment and to roll out larger scale training and awareness programmes.

Because NFI’s are an established technology in parts of mainland Europe, much of the technical know-how and skills are already development. Those skills and knowledge have been transferred to a growing number of practitioners throughout the UK supply chain so the foundations for larger scale adoption are in place.

4.1 Product Supply

Except for sheep’s wool (specifically Thermafleece) all natural fibre insulation is imported from mainland Europe to the UK. Established distributors import full loads to minimise cost and transport impacts. There is a sufficient distributor base and product supply to facilitate a five or tenfold growth in the NFI market from its current level in the short to medium term. Long-term the government needs to support the creation of production capacity for materials such as wood fibre or cellulose insulation in the UK in particular.

This type of increase in capacity requires a rebalancing of standard build practices promoting more timber buildings and modular constructions. This may be more applicable to new build rather than retrofit but it catalyses market growth, increases supply, and lowers prices of NFI’s for retrofit applications. Growth also requires a more achievable route to compliance with established insurers (NHBC or LABC for example).

Manufacture in the UK would require any existing and projected volume to justify the capital outlay. A regulatory approach as taken in France can aid decision making but requires a differentiation in the types of materials used and accepting the benefits of one compared to another. Wood fibre insulation manufacturing capacity in France for example has been increased based on the market created using this governmental approach. If the UK would consider the same approach, then insulation manufacturers would see capital investment as an acceptable risk.

4.2. Training & Delivery

Assessment of the ‘whole building’ is essential (heat loss through all of the elements – (floors, walls, roofs) as well as an understanding of the ‘whole house’ approach from assessors to trades. Differential funding for differing solutions in different types of buildings should be encouraged because the extent of insulation may vary hugely. Wales has defined 7 types of building and are building a model around this to help define solutions.

In the very near term we need to make assessments accessible. All stakeholders need to be encouraged to play their part in making this happen. The Natural Fibre Insulation Group (NFIG) of the ASBP is a collaboration of the main natural fibre insulation brands in the UK and is well placed as a focal point for information and training at a product and associated system level. NFIG members & ASBP are working closely with like minded stakeholders to help build their programmes.

Many “oven ready” programmes exist that would greatly enhance awareness, knowledge, and uptake of NFI’s based systems for existing homes. They just need funding. The work of the Green Register in the West of England is a good example of how skills can be developed, and programmes created that now just need investment and backing.

BEIS has funded a series of pilot projects to address this serious issue, one of which is Futureproof, a collaboration between the Centre for Sustainable Energy and The Green Register, both based in the West of England.

Futureproof has developed a training programme covering all aspects of sustainable retrofit and delivered practical, interactive sessions to SME contractors, the very people who are most likely to carry out works using the Green Homes Grants vouchers and other schemes as they arise.

There are over 60 SME contractors who have either completed or are about to complete the Futureproof training and who are already delivering good quality retrofit across the West of England, putting into practice what they have learned in the training programme.

The Futureproof training programme offers quality assurance for these SMEs who are normally excluded from participating in the governance and QA certification such as PAS 2030/2035 due to the time and resources required to become compliant.

However, the Futureproof training covers all the key aspects of whole house retrofit as laid out in PAS 2035, providing homeowners with the confidence that the trained contractors understand the complexities involved in improving their homes.

Futureproof has been working with the Federation of Master Builders, the Construction Industry Training Board and is in discussions with other relevant organisations such as Retrofit Works, Trustmark, Peter Rickaby, Carbon Coop, Alliance of Sustainable Building Products, Sustainable Traditional Building Alliance and Low Carbon Homes all who are working to ensure good practice retrofit in the UK.

Other organisations including the Association of Environmentally Conscious Building (AECB), Wood Knowledge Wales and numerous independent companies have developed fully formed and scalable training programmes that just need funding to grow.

5. Support Schemes and Programmes

Explicit and implicit barriers exist that effectively prohibit the inclusion of NFI’s in all support schemes to date (except for pilot or demonstrator projects or support schemes run at a very local level). Negative factors include a focus on up-front cost rather than whole life cost, lack of familiarity or skills, incompatibility of standards and accreditations and lack of certainty over timeframes.

Retrofit projects using NFI’s offer excellent value for money over the lifetime of the project recognising that the upfront cost may not be the lowest. Support schemes have historically focused on the lowest up-front cost option that has effectively blocked NFI’s from almost every support scheme to date.

Increasing awareness throughout the supply chain and into stakeholder groups including education is urgently required. Greater acceptance of NFI’s across the broader industry and an understanding that they are tried and tested technologies, proven at scale is needed.

Many NFI based systems or products meet the requirements of current building regulations yet still face barriers with respect to standards and specifications. Greater leeway is needed for a period to allow NFI’s to become more established in the UK. Clearly, this should be achieved without any diminution of quality or standards.

As has been the case with the Green Homes Grant scheme, the timescales involved (even with an extension) and the uncertainty over future schemes are insufficient to encourage those in NFI supply chain to invest.

Add the above together and we have a situation where to date those in the NFI supply chain do not engage with support schemes because they know the race is lost before the starting pistol is fired.

Current funding schemes should be seen as the start of a longer-term programme of meaningful funding for energy efficiency, health, and sustainable improvements to existing homes.

A proportion of funding in future support schemes needs to be ringfenced for NFI’s and other established yet under-utilised technologies. This is the only way that technologies such as NFI can begin to be an option for householders needing support.

A move to zero VAT for all energy efficiency retrofit work is required. Consideration should also be given to ways in which income tax relief could be applied to help cover the cost of energy efficient home improvements.


A copy of the oral evidence given during a session of the Environmental Audit Committee: Inquiry into Energy Efficiency of Existing Homes can be downloaded here.

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