The Kömmerling standard

There’s been much debate about U-values and how companies have made their calculations says Kevin Warner, sales and marketing director of Profine UK and Kömmerling. He suggests that the market should standardise calculations further to create consistency and clarity across the industry.

The introduction of new building regulations, including Part L, has caught some companies out thanks in part to Covid-19, Brexit and cost and supply issues across the sector.

There’s been a rush for many businesses to comply, and in some cases test specifications haven’t been communicated clearly when there’s been the use of butyl sealants, thermal inserts and even Krypton glass – elements that add significant cost to a window or door.

We’ve set out our Kömmerling standard across the Kömmerling 70 and Legend platforms with a U-value of 1.2 W/(m2K) as standard using a typical double-glazed unit and without the requirements for any thermal inserts.

Our new flush sash also achieves this standard with ease, thanks to the six-chambered sash, that also boats a seventh pseudo chamber and additional material for ease of fabrication using the latest TimberWeld and MechWeld technologies.

Elsewhere in our portfolio, the new Kömmerling VS achieves a U-value of 1.3 W/(m2K) – and is capable of 1.2 W/(m2K) with glazing changes – as do the casement, flush and tilt and turn variants within the WarmCore platform, again simulated without butyl sealants and thermal inserts.

We use a standard IGU for measurement, yet there are others that deem the use of non-standard IGUs, sealants and inserts as normal practice, despite the cost and sourcing implications.

Kömmerling 70 is the industry benchmark for profile quality, design and performance, and Kömmerling 76 – which was presented at the FIT Show – boasts a U-value down to 0.79 (W/m2K) with a triple glazed unit.

From a performance perspective there’s little to match our European System 88 platform which can achieve Passivhaus levels of performance down to 0.72 (W/m2K) in both white and with foils thanks to our pioneering prostratoTec technology. This again was presented at the FIT Show as a full window, but also in a vertical cut through format, showing the capabilities and expertise that we have across the group in terms of product engineering.

We can also achieve a U-value of 1.3 W/(m2K) for our PremiLine patio door double glazed and 1.2 W/(m2K) with triple glazing using a dedicated bead. The impressive lift and slide PremiDoor 76 achieves this same standard with the same typical double-glazed unit. With triple glazing options and in the 88mm platform we can also achieve Passivhaus levels of performance. Impressive still is the fact that our WarmCore bi-folding and patio doors also achieve the U-value of 1.3 W/(m2K) with a standard double-glazed unit.

Legislation may well be pushing companies to improve the performance of their products, but we’ve been doing this for years now, thanks to our global footprint and the requirement for our partners to manufacture and install the best performing products in each respective market. Nor should we discard the fact that the overall carbon impact of products has never been under so much scrutiny by consumers, and this no doubt will take centre stage in the years to come.

The Kömmerling standard for energy efficiency is our commitment to effective communication, product evaluation using standard glass units and to a future where energy efficiency credentials will get ever tighter. We’re hoping that the industry works together to ensure that we simulate windows and doors to the same methodologies and under good practice.

In summary, our Kömmerling 70 including flush sash and Legend platforms achieve a U-value of 1.2 W/(m2K), Kömmerling 76 down to 0.79 (W/m2K) and our WarmCore and Kömmerling VS will achieve 1.3 W/(m2K) with a standard double-glazed unit. System 88 will go further still to 0.72 W/(m2K). From a door perspective we can achieve a U-value of 1.3 W/(m2K) for the PremiLine patio door, lift and slide PremiDoor, while the WarmCore patio and bi-folding doors again achieve 1.3 W/(m2K).

Collectively it’s the Kömmerling best practice standard for energy efficiency, something that’s wholeheartedly reassuring to our manufacturing partners and installers.