VIEWPOINT STOCKING FOR
PASSIVHAUS PROJECTS Matt Neary, national sales manager at Knauf Insulation
ONCE SEEN AS a niche, premium option, the Passivhaus building standard is expected to play a bigger role in UK housebuilding from 2025 onwards, with up to 1% of new homes targeting Passivhaus certification next year, and the cost of achieving it predicted to fall . It’s a growing opportunity for builders’ merchants to support customers exploring this approach for the first time.
What is Passivhaus? Passivhaus is an energy performance standard used to achieve thermal comfort solely by post-heating or post-cooling of the air, removing the need for traditional space heating systems such as gas boilers.
Crucially, it sets a standard for the maximum required heating load from heat pumps or mechanical ventilation with heat recovery (MVHR) and this requires a highly efficient, airtight building fabric with minimal thermal bridging.
Buildings don’t have to be officially certified to benefit from this approach. Many builders and self-builders are now looking to build “to Passivhaus standard” without going through the paperwork—stocking the right materials can help them get as close as possible to those
performance goals, regardless of whether they are aiming for official certification.
Passivhaus certified products
Buildings need to follow five principles to achieve the Passivhaus standard: highly efficient thermal insulation, well insulated windows that use low-E glazing to prevent heat transfer, ventilation heat recovery, airtightness and minimal thermal bridges. This requires high quality products that deliver reliable, real-world performance. To simplify design and construction, the Passivhaus Institute has a list of certified building components that have easily comparable test data, deliver high levels of energy efficiency and are suitable for use with other certified components. This helps to simplify design and construction for customers trying to meet the standard.
However, a Passivhaus certified building doesn’t need to contain these products. What matters more is that the products meet performance requirements and can be installed reliably. Airtightness, thermal performance, and buildability are what count in real-world conditions – and Passivhaus certification for a building does not hinge on the use of its certified products.
If your customers are exploring Passivhaus for the first time, having the right range to support them is key. When it comes to insulation there are two considerations to bear in mind: embodied carbon and buildability. Embodied carbon, the total emissions produced outside of operational processes, is not a factor in Passivhaus certification, but there is a commercial opportunity here.
Customers building a house to this standard are likely to be environmentally conscientious and keen to reduce the impact of the construction where possible. It might not always be practical to stock specialist insulation such as sheep’s wool or hemp, but glass mineral wool, for example, has the lowest levels of embodied carbon of any mainstream insulation material in the UK. Buildability is another key factor. For a building to be certified as a Passivhaus, it must be reviewed at several stages, including the planning, design and construction of the building, and crucially, an as-built assessment.
This means customers need materials that are easier to install correctly, because the quality of the final construction in a Passivhaus is heavily scrutinised. Some materials are easier to
achieve the required thermal performance with than others. Rigid boards may offer an improved U-value on paper, but they require precise taping and cutting to avoid air gaps and getting them to sit flush to an imperfect substrate can be difficult.
By contrast, a flexible, fibrous product such as mineral wool will adapt to the substrate and the abutting edges of rolls or slabs will ‘knit’ together. This more forgiving installation experience can help to reduce thermal bridging and minimise air gaps, maximising the thermal performance.
Futureproofing Even if only a few of your customers are asking about Passivhaus today, its influence on UK building practices is growing. Many of the core ideas—reducing energy use, improving thermal efficiency, and measuring as-built performance—are feeding into wider regulations like the Future Homes Standard.
For merchants, this is a chance to get ahead. Stocking buildable, low-carbon products that make it easier to meet Passivhaus- level performance can help differentiate your offer and support customer success. BMJ
16
www.buildersmerchantsjournal.net June 2025
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