What is the Real Performance of your project?

By Knauf Insulation UK & Ireland
August 08, 2022

The housebuilding industry is going through significant change, to raise performance standards and lower its environmental impact. With tightening regulations and increased building quality scrutiny, it is more important than ever to ensure that your insulation is performing to expectations.

This is where the real performance of a product comes into play. Real performance is the idea that a product must perform in the real world, not merely according to notional calculations.

There is often a significant gap between the thermal performance of buildings’ design, compared to how they perform in the real world, because of inconsistencies in workmanship, installation or materials used.

The quality of installation is one of the areas that can affect a buildings’ performance. If each building element isn’t constructed correctly then it can create huge issues both during construction and after completion.

A common issue that arises is unwanted air movement around the insulation caused by gaps in the construction. Rigid insulation boards are prone to these unwanted air gaps because they don't adapt to conditions on site. If the inner leaf is not perfectly flat and uniform, rigid boards will not sit flush with it meaning that air can travel through the cavity and lessen performance. Another consideration when using rigid boards is that all gaps between each board need to be taped with precision.

In contrast, mineral wool insulation is engineered to adapt to minor imperfections in the substrate, so it maintains close contact and preserves thermal performance for the life of the building ensuring the real performance of the building stays as originally specified.

The products used also play a huge part in the real performance of a property. Often builders will look at ways to reduce cost during construction, however this often has a negative effect on the overall performance of the property.

By using lower performing products, it is likely that the performance of the house won’t match the original specification and therefore be at risk of not meeting building regulations as well as giving lower long-term performance.

The new regulations introduce a shift in focus towards measuring a home based on its as-built performance, rather than its notional design. All dwellings built to ADL 2021 must now be assessed using the latest version of the Standard Assessment Procedure (SAP).

Within the new Approved Document L (ADL) updates, the Government has brought in the new Building Regulations England Part L (BREL) report. The BREL report will be used to provide evidence that construction complies with Part L requirements and will be produced at two stages:

  • Design stage BREL report – showing that the house specification will meet its target performance;
  • As-built BREL report – showing that the specified materials have been used to meet the target performance and detailing any substitutions.

The as-built BREL report will also require housebuilders to supply photographic evidence of key stages during construction, to demonstrate that the construction is installed to the required standard. By taking photographs of the insulation at construction stage, you’re able to illustrate evidence of thermal continuity and quality of installation

Factoring in all these points and ensuring you’re building to give real performance rather than notional performance; you’re building houses for now and the future.