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Getting home insulation right

12 November, 2018

Tina Fawcett

Gavin Killip

Tadj Oreszczyn

Reading time: 4 minutes

Done well, home insulation offers many benefits. It helps people achieve comfort at lower cost, lowers energy use and carbon emissions. However, done badly, it can have very negative effects.

Done well, home insulation offers many benefits. It helps people achieve comfort at lower cost, lowers energy use and carbon emissions, helps resolve the damp and mould problems that still plague many uninsulated homes, reduces the risk of cold-related ill-health and may increase the value of the home. However, done badly, it can have very negative effects.

On the Today Programme of 9th November 2018, there was a report about solid and cavity wall insulation schemes which had gone very badly wrong.  Primarily focusing on solid wall insulation, it demonstrated that poor specification and installation had resulted in very serious damp and mould problems, negatively affecting people’s health and quality of life, as well as causing extensive property damage. Many of the cases highlighted were in Preston, funded through a government-mandated scheme. A key problem was the failure to make the insulation weather-tight, leading to water building up between the wall and the insulation, creating damp and mould problems inside. Something which should have been an important improvement, turned out to be just the opposite.

The problems of mould and damp arise from excess moisture in homes. Occasionally, as in the houses in Preston, that water comes in from outside. Neglected properties can be expected to leak eventually, but the shocking part of this report is that water got in as a result of the way in which improvement work was carried out. A much more common source of moisture in homes is condensation generated within the home – from breathing, cooking, bathing, drying clothes etc. Condensation risks are higher as the temperature drops, which is why insulation has helped millions of homes reduce mould growth. Other strategies are still important, though, such as providing adequate ventilation, especially in kitchens and bathrooms.

There are around 8 million homes in the UK with solid walls, mostly built before the 1930s. In general, heat escapes more easily through solid walls than it does through the more common ‘cavity wall’ construction, where there is an internal wall, an air gap, and an external wall. Cavity wall insulation – injecting insulating material into the air gap – is relatively cheap and quick, causing little disruption. Insulation for older solid walls (without a cavity) is more technically difficult to install and considerably more disruptive and expensive. Most cavity walls in the UK have now been insulated, the majority through a range of government and energy company programmes. Very few solid walls have been. To improve people’s health and quality of life, particularly in the least efficient housing, solid walls do need to be insulated, professionally and to high standards. Wall insulation is an important part of ‘whole home’ refurbishment of existing properties to reduce energy use and carbon emissions.

The high-profile failures reported by the BBC show that there is insufficient quality control in an industry characterised by low wages, low inspection rates and conflicts of interest in the compliance regime. Government schemes need to incentivise high quality installations. For any construction project to allow water penetration is simply inadequate and a failure of good practice. The problem is not with the principle of insulating existing homes – which is still a good idea – but with the endemic problem of poor quality and inadequate control and inspection.

CREDS research and expertise aims to contribute to delivering high quality home insulation which will benefit both individual householders and help reduce national energy use. We are investigating routes to low energy ‘deep’ retrofit. Building on earlier research we will be increasing our understanding of the causes of a performance gap in energy efficiency and how smart technologies can help facilitate better performance contracting. CREDS team members are also contributing to initiatives to increase the quality of renovation work. We will use this knowledge to inform government, industry and the research community, to help the UK to achieve better quality, more energy efficient homes.