What is the Performance Gap?

The ‘performance gap’. Chances are you’ve heard about it, but are you up on the detail? In this blog I’ll take a few minutes to explain the performance gap and show why it can’t be an afterthought during design or installation. This is all based around our latest technical bulletin of the same name, so let me give you an overview but don’t skip that fantastic asset!

What is the Performance Gap?

The context in which we refer to the Performance Gap is two-fold. It describes not only the literal gaps between insulation slabs caused by poor installation, poor design or poor product quality, but also the difference or ‘gap’ in thermal performance you’ll notice as a result of these deficits. These gaps go hand in hand to compromise building performance - but there’s a solution.

Correct design and installation

The route to achieving intended thermal performance in buildings begins early in the design stage. Extra measures should be taken to ensure that designs are faultless to minimise the likelihood of mistakes in the installation phase. If specifications change at any point, reviews and recalculations of the designs should be conducted. Designs should be as simple as possible to make life easier for installers – complicated designs may be difficult to follow and they make mistakes more likely.

Specifying the right insulation for each project based on detailed calculations and installing it correctly is the next step to narrowing the performance gap. Common installation mistakes can have detrimental effects, like:

●??????? Literal gaps forming between insulation slabs

●??????? A lack of insulation and continuity at junctions

●??????? Debris and mortar snots in cavity walls

●??????? Incorrect positioning of windows and doors

We've long thought the issue of gaps between insulation can be solved quickly and easily with the right materials. In fact, we've seen the solution in our own products, which is why we recently moved to clearly evidence the ability of ROCKWOOL stone wool insulation to close the performance gap. Based on independently measured data from the University of Salford, when ROCKWOOL stone wool slabs are tightly joined, their edges knit together and provide a continuous insulating layer with trapped pockets of air. This results in no gaps and no associated loss of thermal performance, should they be installed correctly.

Why close the performance gap?

To reduce the energy consumption and carbon emissions of your buildings in line with the government’s net zero targets, the quality of your insulation will play a significant role. Beyond our recommendations, the latest Approved Documents give routes to enhance thermal performance. Additionally, the Future Homes Standard (England) and Passivhaus Standard (Scotland) see further improvements to the building fabric.

It's also worth mentioning that heat-sensitive photographic evidence, as listed in Approved Document L, is now required to prove correct insulation installation, further proving the need to get familiar with the Performance Gap.

You can now download the Performance Gap Technical Bulletin via the ROCKWOOL website, where we go into more depth on the topic and the thermal testing. Or, you can register for an in-person CPD for a more bespoke explanation of the Performance Gap.

If you’re interested in learning more, give me a message or a call!