Time for change

Minimum Energy Efficiency Standards (MEES) comes into effect in England and Wales on 1 April. Adrian Pargeter of Kingspan Insulation looks at the effect this will have.

The new legislation aims to address the worst performing private rental properties by preventing landlords from granting tenancy in buildings with an Energy Performance Certificate (EPC) lower than an E (subject to certain exemptions). MEES will become compulsory for all privately rented properties from 2023.

Estimates suggest that the average annual energy cost for an EPC band G property is £1,150 more than that of an EPC band E property. This additional cost can make it unaffordable for tenants to properly heat their homes, potentially leading to significant health issues. With around 320,000 private rental dwellings in England falling within EPC bands F and G, it is easily understandable why the Government has identified this as a priority area.

When undertaking work on these projects, specifiers should carefully consider options which can raise buildings beyond the minimum standards. In its Clean Growth Strategy, the Government committed to upgrading as many private and social housing properties as possible to EPC band C by 2030. Properties refurbished to an EPC of E may therefore require further disruptive work within a few years. One of the most cost-effective ways to deliver significant long-term improvements is by raising the thermal performance of the building fabric.

Fabric first

Unlike potentially short lived renewable technologies, a well detailed and carefully installed insulation retrofit should continue to perform over the long term with little or no maintenance. While insulation retrofits have typically focused on attics or cavity walls, 45 per cent of all fuel-poor households live in solid walled or hard-to- treat dwellings. It is therefore vital that the external walls on these properties are tackled.

The thickness of the insulation layer in solid wall insulation applications is a key design consideration. Any insulation installed internally will cut into the available living space, while thick external insulation layers can present structural challenges (particularly on taller buildings).

Solid wall insulation applications also require the depth of window sills to be increased. As a result, installing significant thicknesses of insulation can reduce internal light levels, creating dark, unwelcoming environments which are potentially unhealthy for tenants.

In order to keep the insulation depth to a minimum, without compromising thermal performance, it is necessary to install insulation materials with a low thermal conductivity. The latest generation of phenolic insulation boards can now achieve a thermal conductivity of just 0.018 W/m.K, much lower than other commonly used insulation materials. The rigid insulation boards can be quickly and easily installed and are available for both internal and external solid wall applications.

Fire safety

Any improvements to the energy efficiency of existing buildings must not be made at the expense of fire safety, particularly in high-rise constructions. Premium performance rigid phenolic insulation can achieve the required fire performance and negligible smoke obscuration for use as External or Internal Wall Insulation (EWI and IWI), which are two of the most commonly used refurbishment applications.

In addition to providing a solution for low and medium height buildings, specific systems incorporating phenolic insulation are also available for applications above 18 metres. Several systems have been fully tested to BS 8414, and are BR 135 compliant. The BRE holds a register of cladding configurations which have been successfully tested to BS 8414 at www.bre.co.uk/regulatory-testing. It is important to remember that these results only apply to the specific designs tested. Also, recent tests will not yet be listed. You can refer to the manufacturers and/or designer of your current system to get the latest information.

Refurbishment options

A wide variety of buildings currently fall within EPC bands F and G and the most appropriate solution for each will, of course, depend on its unique characteristics and requirements. Premium performance phenolic insulation boards offer a proven option in specifications where fabric performance is identified as a priority, allowing the desired level of thermal performance to be met with a slim, lightweight construction.

Adrian Pargeter is head of technical and product development at Kingspan Insulation