When the government made a legal commitment in June to achieve net zero greenhouse gas emissions by 2050[1], improving the energy efficiency of buildings was identified as “a key pillar of any credible strategy” to meet that ambitious target[2]. Since it is well established that in 2050 around 80%[3] of the buildings we will be using are standing today, making sure that our current building stock is up to scratch will play an important part in meeting these critical decarbonisation goals.
For those working in refurbishment, the opportunity is clear. However, the challenge is to identify ways of improving building envelope performance within the constraints of an existing structure. In many cases a solution can be supplied by the use of insulated facade systems, which offer a versatile, durable and cost-effective way to transform both appearance and energy efficiency, helping to futureproof against likely regulatory and climate changes.
Beyond requirements
There is no doubt that if we work solely within the framework of the current building regulations for England and Wales, the thermal performance of refurbishment projects will fall far short of the level of performance that is needed. Instead, it may be more useful to take the anticipated targets of the Minimum Energy Efficiency Standards (MEES) as a more robust and effective approach, both to achieve better levels of energy efficiency and to protect building owners against future mandates.
Driven by the Energy Performance of Buildings Directive (EPBD), MEES currently prevents both domestic and non-domestic private landlords from granting or renewing tenancies if the building does not achieve a minimum Energy Performance Certificate (EPC) rating of E. This will become compulsory for all privately-rented properties from 2023, regardless of whether a tenancy agreement already exists. This is still a modest starting point, but in 2017 the government released its Clean Growth Strategy wherein it made clear that it aims to raise “as many homes as possible” to an EPC of C by 2035 “where practical, cost-effective and affordable”[4]. It also has a statutory target of moving fuel-poor homes to EPC band C by 2030.
However, even tougher regulations will need to be enforced if we are to meet the net zero by 2050 target. On 12th July, the Department for Business, Energy and Industrial Strategy (BEIS) released a report on the energy efficiency of UK buildings. Highlighting Scotland’s energy efficiency programme, which seeks to make existing buildings near zero carbon wherever feasible by 2050, it called for the government to “treat the energy efficiency of all buildings across the UK as a national infrastructure priority and implement the policies to reflect this.”[5] Its suggestions include the urgent outlining of how the Clean Growth aims will be achieved and the raising of the MEES to EPC B for commercial properties by 2035.
Whilst it is not yet clear how the government will respond, if you are going to invest in upgrading a building, it makes sense to ensure that the building envelope exceeds current standards, protecting against the need for further work, whilst reducing long-term running costs and carbon emissions.
Freston Road before refurbishment
Fabric first
When upgrading the thermal efficiency of a wall construction, the key elements to consider are the insulation choice, airtightness, detailing and how to limit thermal bridging. From simple, single-component insulated panels to multi-layered built-up designs, there are a number of through-wall facade systems which tick these boxes without compromising on other performance aspects. These allow different combinations of insulation and rainscreen finishes to be selected to suit each project.
For example, substructures which use modern closed-cell insulation can achieve U-values as low as 0.08 W/m2K, helping to achieve excellent fabric performance with a slim wall build-up. Alternatively, whilst much thicker volumes will be needed to achieve the desired U-value, mineral fibre insulation can provide additional acoustic benefits and, provided it has achieved an A1 or A2-s1, d0 European classification, is deemed to automatically comply with fire safety building regulations for buildings above 18 metres. Note that, even when A1 or A2 rated cladding and insulation is being used, it is advisable to ensure that any full facade system is backed with data from suitable fire safety testing wherever possible.
If designed and installed correctly, these insulated substructures can also help to minimise air leakage through the building envelope, capable of achieving an airtightness of <1m3/hr/m2 at 50Pa. Where insulated panel systems are being used, they can also reduce the risk of error during the install phase and allow the building envelope to be made weathertight at an earlier stage, reducing construction timescales.
In all weathers
As the Committee on Climate Change (CCC) states in its recent progress report, “even if net zero is achieved globally, our climate will continue to warm in the short-term,”[6] leading to more of the extreme weather patterns we have been seeing across the globe. Therefore, it is vital that we ensure our buildings are not only designed to reduce their contributions to the climate emergency but are ready to stand up to its effects.
The principal purpose of the building envelope is to protect the internal spaces and occupiers from the elements. Addressing the fabric performance and airtightness of the wall constructions will help occupiers to more effectively regulate internal temperatures, retaining more heated air in colder weather and keeping warm air out on hotter days. However, consideration also needs to be given to ensuring that facade systems can withstand harsh wind, rain or sun conditions, so that the occupiers remain safe in extreme conditions and the building’s aesthetics are maintained over time.
Weathertightness
Systems are available which have been tested to the ‘Standard for systemised building envelopes’ from The Centre for Window and Cladding Technology (CWCT). This includes rigorous testing in three key weathertightness performance areas: resistance to water penetration, resistance to wind loads, and the control of air leakage – as dependent on the individual application.
It is also important to consider how the outer facade material itself will be affected by weathering. Materials that have been treated with a highly resistant UV coating will withstand bleaching by the sun, helping to maintain the desired aesthetic. Meanwhile, materials such as Corten steel are designed to embrace the weathering process, forming a patina veneer which shifts in colour over time.
Whatever solution is selected, engaging with a manufacturer’s technical support team during the installation phases can ensure the finished refurbishment meets the designed performance requirements, from getting advice on specific on-site issues to receiving standard detailing information.
A new outlook
Achieving the net-zero emissions target will be a challenge. However, by using existing skills and flexible building technologies such as through-wall facade systems, the refurbishment industry can lead the way in ensuring that the UK building stock is brought up to standard quickly, safeguarding the future of our buildings and our planet.
For further information, please contact:
Kirsch Bowker, Head of Marketing
M: +44 7392 103366
