Written evidence submitted by the Mineral Wool Insulation Manufacturers Association (MIMA) (DHH0051)


  1. The Mineral Wool Insulation Manufacturers Association (MIMA) is grateful for the opportunity to submit evidence to the Decarbonising Heat in Homes Inquiry. MIMA fully supports the Government’s intention to transition to a future where heat pumps and other low carbon systems are used to heat homes in place of fossil fuels. Heat pumps are a proven technology, particularly in other countries where installation numbers are currently higher than in the UK. Electricity grid decarbonisation and reduced carbon factors now makes their deployment at scale in the UK an obvious choice.


  1. There will, however, be complementary policies and regulations needed to support the transition. Alongside general quality assurance, it will be extremely important to ensure that the fabric of buildings receiving new heating systems is well insulated and is performing as intended in use. Our short submission focuses on this point, falling under Question 2.


Question 2 - What key policies, priorities and timelines should be included in the Government’s forthcoming ‘Buildings and Heat Strategy’ to ensure that the UK is on track to deliver Net Zero? What are the most urgent decisions and actions that need to be taken over the course of this Parliament (by 2024)?


  1. The Committee will be aware that having good insulation and a building envelope that performs as it was designed to will be essential if householders are to have the comfort levels and lower energy bills they expect from houses fitted with low carbon heating systems.


  1. Where heat pumps are concerned, the radiators will operate at lower temperatures (around 55C) compared to conventional heating, and so houses must be effective at retaining heat in winter.


  1. The Energy Saving Trust makes this point clearly on their website for consumers: “Unlike gas and oil boilers, heat pumps deliver heat at lower temperatures over much longer periods. If you are installing an ASHP to replace a gas or oil boiler, you should consider whether you can also upgrade your insulation to get the most out of your ASHP. You might also consider fitting larger radiators or underfloor heating.[1]


  1. The Centre for Sustainable Energy also states: “If you are considering a heat pump it is very important to make sure your home is well insulated as heat pumps work best in buildings that require little energy to maintain a temperature once it has been reached.”[2]


  1. The Government’s Impact Assessment for the recent consultation Future Support for Low Carbon Heat notes that there are health benefits for occupants associated with improving a building’s energy efficiency alongside the installation of low carbon heating…”making energy efficiency improvements ahead of installing a low carbon technology can lead to a warmer home and therefore improve the health of occupants, for example by reducing their risk of cardiovascular and respiratory diseases as a result of warmer internal temperatures. If monetised, this would have a positive impact on the SNPV of the Clean Heat Grant.[3]


  1. MIMA would go further and suggest that if the public shifts to using low carbon heating systems at scale, and then struggles to stay warm in winter at reasonable cost (potentially due to a failure to insulate sufficiently beforehand) this could result in a backlash against technologies such as heat pumps and eco homes in general. We must therefore ensure that future policies, including those set out in the forthcomingBuildings and Heat Strategy”, drive insulation upgrades and the deployment of low carbon heating simultaneously.


  1. It should also be remembered that there is still much essential insulation work to be done. For example, a recent article by the Energy and Climate Intelligence Unit (ECIU) highlighted that “Research carried out by the EST for the Government found there were 3.6 million uninsulated cavity walls and a further 2.3 million homes with substandard wall insulation. It also found more than 6.6 million homes with inadequate loft insulation. Separate Government figures show that the vast majority of solid wall homes – about 7.5 million – do not have insulated walls.[4]


  1. Lastly, the ECIU also highlights in the same article a recent study by Element Energy and E4tech which makes clear the possible financial of cost of failing to properly insulate homes. The study suggests tens of £billions could be saved by including insulation measures during the transition to a more electrified energy system[5].


Real performance


  1. The Government’s commitment to ensure more homes are heated with low carbon systems creates a renewed imperative to effectively assure the quality and performance of the fabric of the retrofitted homes. The key is to have genuinely well-performing fabric, in reality, not relying solely on modelled estimates of performance.


  1. The switch to heat pumps, which use electricity instead of gas or oil for heating, could result in higher energy bills than expected if the fabric is not performing well, even with their impressive coefficients of performance. This is because unit prices for electricity are currently around four times that of gas[6], and are forecast to be higher still in 2025[7]. Every extra, unanticipated unit of electricity needed to heat a leaky home would come at a higher price than now.


  1. Using more electricity than expected would put extra pressure on the electricity grid, especially if space heating demand peaks across the population not only at certain times of day, but in specific days and weeks of cold weather. In these periods ASHPs, for example, will be driven harder to heat the air and their coefficients of performance will worsen, further driving demand for heat and pressure on the grid. If the building fabric is not performing as expected, then this vicious cycle will happen more often.


  1. To counter the potential impact of this on people’s energy bills it will be necessary to keep actual energy demand for space heating down to low, feasible levels and deliver as close to the design performance as possible. In short, it will be critical to the broader success of decarbonisation policies that energy efficiency standards are robust, and that these standards are delivered in reality.


  1. This general point has been made effectively by Jan Rosenow in the case study of his installation of a heat pump: “It is important to note that installing a heat pump in isolation in existing, and often inefficient, homes is not advisable. I have made the argument elsewhere for aligning energy efficiency and heat decarbonisation to maximise carbon reduction and avoid oversized heating systems. This is why we invested in energy efficiency measures in our Victorian 1880s home alongside the heat pump. We insulated the floor throughout, installed mostly triple or double glazing and insulated the attic[8].


  1. Jan also managed to cut his fuel bill costs by working with his energy provider to supply his heat at points in the day when the cost was lowest. This strategy clearly works best in a well-insulated building, where the heating can be on at non-peak times, and the house stays warm throughout the day.


  1. MIMA would therefore recommend that future policies on low carbon heat incorporate clear fabric performance requirements. For example, the Clean Heat Grant scheme could be conditional on a minimum fabric requirement, similar to the RHI.


  1. Such policies would also link well with the Government’s longer-term commitment for a net-zero economy, and shorter-term goals such as to get all existing housing up to at least an EPC band C by 2035. It is hoped that long-term Government-supported funding and incentives will be coming online to help householders pay for energy efficiency measures once the Green Homes Grant ends, and for those not eligible for support under the Energy Companies Obligation.


  1. The form of requirements will be very important. For example, policies should not only require that that the fabric of buildings to benefit from grants for low carbon heating are insulated, such as the loft or the walls, it may also be necessary to specify the standard to which they are insulated, and then offer additional cashback or rewards for consumers who choose to work with suppliers who verify that the performance.


  1. Ideally, those standards should, as a minimum, align with Building Regulation requirements e.g. a loft should achieve a U-value of 0.16 W/m2K and the level of heat loss be commensurate with that U-value.


  1. The adoption of smart meters should also open up avenues for verifying fabric performance that have not been possible before.


  1. Historically, delivering fabric improvements to individual homes or groups of homes has not been accounted for in terms of the impact on home electricity demand because that impact was difficult to quantify. However, the introduction of smart meters and other similar technologies, means this can change.


  1. A good example is BEIS’s SMETER (Smart Meter Enabled Thermal Efficiency Rating) programme now running. This incentivises participants to do what hasn’t been previously possible – put a figure on a home fabric’s core efficiency and be able to quantify how much that fabric efficiency has been improved by an energy efficiency intervention applied to the home, in terms of likely reduced energy demand.


  1. Such technologies – whether part of the SMETER programme or being developed outside of it - offer significant potential demand reduction opportunities where the core space heating demand is met by electric heating. Incentivising the continued development of these will be necessary.


  1. In conclusion, we would invite the Committee to use their influence to stress the need for future policies on low carbon heat and insulation/fabric to go hand-in-hand. The mass roll out of low carbon heating will be most successful when deployed alongside policies which deliver well insulated, well performing buildings.


November 2020



[1] See https://energysavingtrust.org.uk/renewable-energy/heat/air-source-heat-pumps

[2] See https://www.cse.org.uk/advice/renewable-energy/ground-source-heat-pumps

[3] See https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/881623/future-support-for-low-carbon-heat-impact-assessment.pdf

[4] See https://eciu.net/analysis/briefings/low-carbon-heat/energy-efficiencys-role-in-heat-decarbonisation, which references https://www.theccc.org.uk/wp-content/uploads/2016/10/Next-steps-for-UK-heat-policy-Committee-on-Climate-Change-October-2016.pdf. The figures quoted in the ECUI article are broadly in line with MIMA’s understanding.

[5] See https://nic.org.uk/app/uploads//Element-Energy-and-E4techCost-analysis-of-future-heat-infrastructure-Final.pdf

[6] Figure for the standard electricity tariff in Table 12 SAP 10.1

[7] See Reference Scenario, Annex M https://www.gov.uk/government/publications/updated-energy-and-emissions-projections-2018

[8] See https://foresightdk.com/why-i-replaced-my-new-gas-boiler-with-a-heat-pump/