Sustainability

The Egan Report, ‘Rethinking Construction’, highlighted the need for offsite manufacture and standardisation to address issues such as skills shortages, reducing build times and costs and improving quality/reducing defects. The construction industry has responded with an increasing number of structural panel building systems, offering what Egan called for.

However, few of these systems address another key industry driver; that of sustainability (although many will claim to with varying degrees of truth). To fully satisfy the label of ‘sustainable’, a product needs to satisfy two important criteria: the materials used must themselves come from sustainable sources and the performance of the product, in the case of structural panels, must be such that they provide high levels of thermal performance (amongst other benefits) that minimise the heating requirement and, therefore, production of CO₂ emissions.

Inherent Sustainability
Excel EVT structures and, in particular, TRADIS ‘zero heat’ panels are inherently sustainable. The thermal performance of the zero heat panel, for example, delivers a U value of 0.14 W/m²K, which compares favourably with the latest revision to Part L of the Building Regulations (this demands a U value of 0.35 W/m²K). This thermal performance means that in most cases, a space heating system will never be required and, if one is fitted, it will only be used on unusually cold days. As a result, CO₂ emmissions from heating systems can be dramatically cut.

Much of the thermal performance of TRADIS panels is due to the low thermal conductivity value of the Warmcel 500 insulation, which is only 0.036 W/mK. This, in combination with the other materials used in the panels and their airtight design, delivers the ‘zero heat’ performance.

Low Embodied Energy
Because it uses a purely mechanical refibreising process to transform the ‘raw material’ newsprint into high performance insulation, Warmcel 500 has the lowest embodied energy of any mainstream insulation material. Free from added formaldehyde, CFCs and volatile organic compounds (VOCs), Warmcel 500 is also resistant to biological and fungal attack, treated against insects and is unattractive to vermin.

Reduced Material
The Masonite beams used for the frame of the panels combine extreme strength with light weight - beneficial in reducing foundation requirements for a building.

The beams have flanges manufactured from sustainable Swedish Whitewood with a web of Masonite K40 structural board manufactured from forest thinnings and wood waste – offering outstanding strength and rigidity. As a result, the beams are lighter than solid timber, do not warp or twist and dramatically reduce the cold bridging effect through the structure by minimising the web thickness to 8mm. Because only the flanges of the beams are made from solid timber, they will use around 40% less material than, for example, solid timber wall studs.

Both Panelvent and Paneline sheathing used on TRADIS panels are manufactured entirely from wood waste. They do not use any glue in the manufacturing process, relying on natural lignin in the timber as the material binder. Because there are no glue lines, the material cannot suffer from delamination, which is a major advantage for a sheathing board. Natural waxes are added to the formulation to achieve the required sheathing performance.

Beyond Egan
As far as Egan goes, structural soundness and reliability of build are prerequisites. The building regulations demand ‘tougher’ thermal performance. Sustainability, driven by Government and private individuals recognising the need for a long-term strategy, is now also a major requirement for some specifiers. As yet there aren’t a plethora of systems that satisfy all three criteria, but TRADIS is one such solution.