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Picture perfect installations

by Jennie Ward

Jonathan Ducker, Head of Regulatory Affairs at Kingspan Insulation, discusses the new standards due to come into force that are expected to include compliance reports requiring installers to provide evidence, including photographic updates, to prove that insulation is correctly installed and matches the designs…

Next year, new energy efficiency standards are due to come into force in England and Wales (in their regional versions of Part L 2021 to the Building Regulations). In addition to setting tougher performance targets, including lower carbon emission levels, these documents are also expected to include new compliance reports. These will require installers to provide evidence, including taking pictures during the build, to prove that insulation measures are correctly installed and match the designs.

Why are compliance reports being introduced?
One of the focuses within the new regulations is tackling the so called ‘Performance Gap’ between a building’s energy performance on paper, and what it actually achieves. This can be significant with research suggesting that heating demand for new homes can often be two to three times higher than anticipated.

In practice, the design of insulation measures, and the way they are installed, can contribute significantly to this underperformance. An obvious way this can happen is where the specified insulation is switched out for an alternative product or thickness in the final build. For example, whilst foil faced rigid insulation such as PIR or phenolic boards look virtually identical on the shelf, they can have very different thermal conductivities (also known as lambda values). This is basically the measure of how effective they are at preventing heat loss. This means if you change the product from the original specification, it can notably increase heat losses.

“It is crucial that installers then ensure that what is built matches up with these details, as even minor changes or gaps can lead to extra heat losses”

Jonathan Ducker, Kingspan insulation

Issues with poor design or workmanship can also create thermal bridges. These can occur where materials which are more conductive to heat than the insulation are allowed to form a ‘bridge’ between the inner and outer face of a construction – effectively providing a fast-track for heat to escape. This can happen where there are gaps or inconsistencies in the insulation layer (often at junctions around windows and doors, or between the different construction elements such as the wall and floor) or where you have penetrations or interruptions in the insulation (such as pipes and cables or wall studs).

Heat always looks for the path of least resistance, so as we insulate buildings to a higher level, these bridges take on more importance and can account for around 30% of the total heat loss from a property if not properly addressed.

To prevent this, all key junctions should be carefully pre-planned in the design stage, with specifiers either creating bespoke details (known as Psi-values) that minimise their junction heat losses, or utilising details provided by manufacturers (or other libraries), where these losses have already been carefully addressed. It is crucial that installers then ensure that what is built matches up with these details, as even minor changes or gaps can lead to extra heat losses. This is part of the reason why the new compliance reports are being introduced.

What are the new compliance requirements?
In England and Wales, project teams will need to fill in Building Regulations England Part L (BREL) or Building Regulations Wales Part L (BRWL) Compliance Reports which will be submitted to Building Control.

The Compliance Reports are expected to be based on the SAP/SBEM modelling carried out during the design of the property which is used to calculate its expected energy demand and carbon emissions. This includes various aspects of the building specification and design including the insulation levels and products and the make, model and performance of heating and ventilation systems. This will need to be signed off by an energy assessor to confirm the designs are compliant.

Installers will then be required to provide evidence that the completed construction matches up to the designs. This includes taking photographs of the insulation measures at all key junctions including sills, jambs and the eaves. If deviations are found, it may lead to a property being deemed non-compliant, so it is important that installers pay attention to ensuring the correct products are used and that details are accurately installed. Something as simple as window placement within a wall can have a massive impact on heat losses.

Details focus
The final versions of the new regulations are anticipated to be published by the end of the year, with the domestic requirements then coming into force six months later. To avoid the potentially significant costs of remedial work, it is important to take steps now, to ensure your practices are up to standard and will hold up to scrutiny.


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