Scotframe Val-U-Therm PLUS® For PassivHaus: Probably the Best U-Value Wall in the World

Building system

Scotframe exclusively offers the Val-U-Therm PLUS® building system, which offers some best-in-class performance for PassivHaus construction

From the first PassivHaus in UK for rent (Green Apple Award winner) to examples that exceed the PassivHaus standard, Scotframe Timber Engineering has been in the vanguard of building to PassivHaus standards for many years.

Well known as a UK market leader in full timber frame packages for new housing and commercial projects, Scotframe now exclusively offers the Val-U-Therm PLUS® building system. Val-U-Therm PLUS® state-of-the-art wall U-values of 0.08 W/m2K are probably the best in the world.

A key factor in achieving this remarkable performance is that the insulation is injected in quality-controlled offsite factory conditions.  The foam expands into every nook and cranny, providing a best-in-class BR443 U-value correction factor of zero.

One of the more important aspects of PassivHaus is that it requires the whole building envelope to work in unison to provide optimum performance. This is where an integrated building system like Scotframe Val-U-Therm PLUS® comes into its own. It offers wall, floor and roof panels that have been thermally engineered to perform as an optimum combination. As well as excellent thermal insulation performance, details are available to minimise thermal bridging and give excellent airtight fabric levels.

The Maryville PassivHaus in Loch Lomond and the Trossachs National Park delivered a total primary energy demand of 69 kWh/m2a (compared to a PassivHaus requirement of 120 kWh/m2a) using the Fabric First thermal detailing offered by Scotframe.

This approach is suitable for commercial as well as domestic buildings. The Scotframe approach achieved an air tightness of 0.475 ACH when constructing the Rocking Horse Nursery at the University of Aberdeen, which caters for 78 pre-school children.

This Fabric First approach is transported to site in flat-pack configuration and provides a “fit-and-forget”, low maintenance thermal solution unlike many other low energy consumption technologies.

But where the expertise of Scotframe really scores is that it can offer buildings of beautiful design while matching these technical requirements. Not just boring rectangular boxes, but homes and buildings to match you and your clients’ requirements, lifestyle and aspirations.

This provides homes and buildings that are warm and draught-proof in winter; cool and well ventilated in summer; healthy for all the family; and with remarkably low energy bills. Independent research has shown that Scotframe Val-U-Therm PLUS® allows the construction of typical family homes that cost less than £95 a year to heat.

The environmental and sustainability credentials of building materials are of increasing interest in the client community. The Val-U-Therm PLUS® building system uses FSC & PEFC chain of custody timber and its insulation has zero ozone depletion potential (ODP); is CFC-free, HFC-free & HCFC-free and has a Global Warming Potential (GWP) of less than 5. This means it has a BRE Green Guide A/A+ Rating (as straw bales/sheep’s wool) and is recyclable.

Building to PassivHaus standards is not necessarily more expensive or time-consuming if an integrated building system like Scotframe Val-U-Therm PLUS® is used. One study by Edinburgh Napier University compared the cost per square metre of superstructure using 10 different building systems for 27 homes. Scotframe Val-U-Therm cost £1,092 when built to PassivHaus standards, while the other nine systems ranged from £711 to £1,138 when built only to existing Building Regulations.

Similarly, the Scotframe approach took 65 days to PassivHaus standards, whereas the other 26 homes ranged from 49 to 126 days, again only being built to Building Regulations.

The Scotframe Val-U-Therm® building system was originally launched in 2011 and is well proven, having been involved in building over 8,000 homes. The approach has been independently accredited by the British Board of Agrément – this includes verification of structural performance, behaviour in relation to fire, thermal performance, condensation risk, sound insulation and durability. The Systems Certificate notes that the panels will have a 60-year minimum service life – twice the mortgage cycle. It is accepted by financial institutions, NHBC, Premier Guarantee, etc. Scotframe Val-U-Therm PLUS® has its own BBA Certificate 17/5421.

Scotframe Timber Engineering and Val-U-Therm are proud to be part of the Saint Gobain Group of Companies.

Gregor Davidson of Ellon-based Cairnrowan Custom Homes, who only builds A-rated homes and almost exclusively uses Scotframe kits said: “My clients were very keen on the eco side of the build and we manage to achieve airtightness of 0.38 air change per hour and an as-built EPC of 97%. This is well down into Passivhaus status.”


Malcolm Thomson

Sales Director

Scotframe Timber Engineering

Tel: +44 (0)1467 626823


Please note: this is a commercial profile


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