Insulation Manufacturers Association                            SBE0028


Written evidence from the Insulation Manufacturers Association


Insulation Manufacturers Association (IMA) is the Trade Association that represents both the polyisocyanurate (PIR) and polyurethane (PUR) insulation industry in the UK.  Its members manufacture rigid insulation that provides c40 per cent of the total thermal insulation market into the UK. IMA's membership comprises all of the major companies in the industry, including manufacturers of finished PIR and PUR insulation products, as well as suppliers of raw materials and associated services.



How can materials be employed to reduce the carbon impact of new buildings, including efficient heating and cooling, and which materials are most effective at reducing embodied carbon?


It is widely accepted that buildings should adopt a fabric first approach, before designating mechanical and/or active systems as this approach optimises build quality and ensures the as-built performance matches the design performance.


However, it is also essential that regulations set robust assurance regimes, incentives for better buildings and penalties for those that do not perform as predicted.


Methods for reducing the need for energy consumption via a fabric first approach include:


Concentrating on delivering a fabric first solution is generally considered more sustainable than relying on energy saving technologies, or renewable energy strategies, as these latter solutions can be expensive, have a high embodied energy or not be utilised suitably by the occupants. This is apparent when considering fabric enhancements are the most common retrofitting technique implemented in existing properties (including improvements to insulation and glazing efficiency).


Furthermore, the inclusion of a high-performance thermal building envelope reduces the final energy demand to be provided by low carbon/renewable systems, resulting in a reduced dependence on such technologies and improved overall resilience.






What role can nature-based materials can play in achieving the Government’s net zero ambition?


Insulating materials must have a low thermal conductivity potential. The second law of thermodynamics states that heat will always travel from a relative area of higher temperature to an area of lower temperature in order to reach equilibrium across the energy differential – this movement of heat energy is defined as ‘thermal flux’.


Subsequently, suitable insulating materials have a low thermal conductivity in order to limit heat flux across the thermal gradient and maintain the desired temperature variation, for example, between the internal space and the external environment.


There is a vast array of insulation materials that can be utilised as insulants within the construction industry. These solutions range from advancements in material science and the polymerisation of organic chemical compounds derived from virgin fossil fuels to unprocessed, naturally occurring materials such as wool and flax.


Generally, insulation materials can be divided into three main categories: mineral, organic synthetic and natural (plant and animal). Within these three divisions there are two further subcategories, depending on material structure – fibrous and cellular. Together, these classifications broadly outline all of the insulation materials currently available for utilisation in the built environment.


Fibrous materials retain air between the individual strands of constituent fibres, preventing heat transmission via convection and also limiting conductive losses by reducing the interaction of gas molecules within the material; these materials are typically flexible owing to their structure.


Cellular insulation materials, on the other hand, are generally more rigid structures with pockets of trapped gas forming in the interstitial spaces when manufactured/ installed; these chambers of trapped gas inhibit the process of convection. Gaseous blowing agents have a lower convective potential than air, to further reduce the transmission of heat within the material.


The main insulation materials readily available are presented in table 1of our publication “Insulation for Sustainability. A detailed summary of the insulants categorised within the table is available in Appendix A of the same document.

What role can the planning system, permitted development and building regulations play in delivering a sustainable built environment? How can these policies incentivise developers to use low carbon materials and sustainable design?


The Energy Saving Trust (EST) has proposed a revised national strategy to replace the Zero Carbon Homes Initiative. This would necessitate that all new homes are built to a 2050-ready standard, in order to achieve the net-zero carbon target in the next thirty years. A 2050 ready home is defined by the EST as having minimal energy use and net carbon emissions over a year of operation, as a result of high levels of insulation, low water demands and direct connections to renewable energy systems. Furthermore, the EST identifies energy efficiency as ‘the most effective long-term guarantee of a low carbon emission housing stock’. A 2050-ready home would need to meet minimum fabric efficiencies, which would considerably exceed the current building regulations, to help ensure the legally binding targets are achieved.


At a more regional level, the London Energy Transformation Initiative (LETI) has proposed various strategies and influenced policy produced by the Greater London Authority (GLA), in order to generate policy guidance that steers developments in London to zero carbon and which can be eventually applied to the rest of the UK. The recommendations put forward by LETI include the following requirements:



Furthermore, 67% of local authorities across the UK have responded to the current climate emergency by setting their own stretching planning targets. Local authorities are much better situated to determine local requirements and achievable objectives. The UK’s ability to slow climate change depends on individual planning authorities taking ownership of the problem at a local scale, setting ambitious targets in order to precipitate a larger and more co-ordinated response nationally to surpass the more conservative targets administered by the national governments (see figure 9 of our publication “Insulation for Sustainability).


Exeter City Council and Nottingham City Council have been praised as frontrunners in the arena of setting precedent in the UK with respect to the Passivhaus and Energiesprong standards, respectively. Exeter Council has commissioned new buildings to the Passivhaus standard and required developments to be designed to projected 2030, 2050 and 2080 climate scenarios. Nottingham City Council has been the first in the UK implement the Energiesprong standard in 200 social houses – funded by subsidies from installed renewable technologies and a ‘comfort plan’ levied on tenants.


One of the most influential and most well developed voluntary standards in practice internationally and in the UK, is the Passivhaus standard – through which buildings are designed to use very little heating and cooling energy, with a design focussing on fabric efficiency and airtightness. According to the Passivhaus Trust there are over 1,000 Passivhaus homes in the UK.


The Energiesprong standard is another new-build and refurbishment approach that measures the operational energy consumption as opposed to the modelled performance and stipulates substantial fabric improvements over the current guidelines.


Additional legislative measures must be implemented in order to ensure new developments are built to consider future climate conditions and the risks associated with events such as overheating and flooding. The UK’s new National Planning Policy Framework encourages local planning authorities to consider resilience to climate change. However, the UK’s national building energy assessment tool; Standard Assessment Procedure (SAP), both the current SAP2012 and the upcoming SAP10 methodology, do not currently require a detailed overheating assessment.


Nevertheless, summer overheating of buildings is beginning to be considered at a local level. The new Draft London Plan (2017) requires major developments to demonstrate how they will reduce the risk of overheating and reduce the reliance on air conditioning.

Should the embodied carbon impact of alternative building materials take into account the carbon cost of manufacture and delivery to site, enabling customers to assess the relative impact of imported versus domestically sourced materials?


Consideration must be given to the raw materials and the energy consumed to fabricate materials. Additional components of the life-cycle must also be analysed in order to attain a truly holistic perspective. These include ancillary factors such as extraction, processing, transport, distribution, maintenance, re-use, recovery and disposal. The life-cycle stages associated with whole life carbon and embodied carbon are illustrated in figure 22 of our publication “Insulation for Sustainability, in line with the European Standard EN15978.


We would recommend that a comprehensive life-cycle assessment (LCA) is completed where possible to gain a high-fidelity understanding of overall embodied carbon and energy associated with these wider variables and provide a more rigorous evaluation.


Assessing the embodied impacts of insulants is pertinent to BREEAM and LEED certifications which require construction materials to be assessed to recognise and encourage the preferential incorporation of materials with a low environmental impact (Mat01; life-cycle impacts and MRc1; building life-cycle impact reduction – applicable BREEAM and LEED credits, respectively). Industry-standard assumptions and the relative impact of these between the major categories of insulants, focussing on the raw materials and manufacturing energy requirements, can be found in our publication “Insulation for Sustainability

How should we take into account the use of materials to minimise carbon footprint, such as use of water harvesting from the roof, grey water circulation, porous surfaces for hardstanding, energy generation systems such as solar panels


As indicated above, it is essential for the energy performance and cost effectiveness that a fabric first approach is taken before other solutions are implemented.

What can the Government do to incentivise more repair, maintenance and retrofit of existing buildings


There have been numerous schemes to improve the efficiency and energy performance of existing buildings over the past 25 years or so, but each one has failed to deliver the improvements promised, despite a willingness across the RM&I sector to implement these improvements, as well as having the knowledge and materials to do this.


These failed schemes indicate that it is not easy to devise a model that works and achieve the buy-in essential to improve existing buildings.   It is estimated that the average cost of improving an existing property to an EPC C rating will be around £20,000 and yet the return on that investment is not financially attractive under a normal cost benefit analysis.  Unless a national retrofit strategy, which includes a more attractive financial incentive is developed, all schemes will continue to face the problems of previous attempts and the existing housing will fail to be improved to a standard essential to meet the net zero carbon target of 2050.



May 2021