Client: Tesco
Type of works: supply of Metsä Wood engineered timber for low-energy, fully insulated structural panels.

Low-energy, fully insulated structural panels manufactured using engineered timber from Finnforest have been utilised in the construction of Tesco’s new store in Crediton, Devon. Designed by Metsä Wood and Tesco to deliver an airtight and energy-efficient wall solution, the engineered timber systems were fabricated and installed by timber frame specialist, Pinewood Structures.

Tesco is well known as a driving force for carbon reduction and energy efficiency in the retail sector. The design, construction and operation of its buildings to reduce the use of energy, thereby improving running costs and lowering carbon emissions is part of the company’s overall plan to halve the carbon emissions from its buildings alone by 2020.

This plan involves the design and erection of buildings with increased airtightness, delivering optimum u-values therefore sustainable energy efficiency for each Tesco store.

Working with Tesco, Metsä Wood designed its low-energy panels using a Kerto frame, Finnjoist, a breather membrane and an OSB skin. The depth of the Finnjoist, Metsä Wood’s fully engineered i-joist, provides a large cavity void, which can be filled with insulation. In addition, a vapour barrier ensures that interstitial condensation does not compromise the warm wall effect. With target u-values of around 0.3, the innovative panels delivered 0.2 and aided an air rotation of just 1.87 per hour for the store.

Geoff Arnold, Managing Director of Pinewood Structures, the timber frame specialist for the manufacture and construction of the wall panels at the Tesco store at Crediton, said, “The structural rigidity of the Finnjoist creates the perfect foil from which to build up an airtight and low energy insulated panel. This is because the depth of the Finnjoist provides space to introduce additional insulation while the environmental certification of Metsä Wood’s timber underpins the robustness of the specification.”

For the Tesco store at Crediton, a bespoke Larch cladding was specified in order to maximise the aesthetic benefits of the timber’s natural appearance, which was in keeping with the building’s environmental and sustainable design principles.

The low-energy panels were fabricated offsite to Finnforest’s design using precision engineering by Pinewood Structures, who then delivered and erected the panels and installed the cladding in line with the build programme.