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Lessons about the behaviour of insulation

Stuart Borland is an architect - Dundeetrained - who is busy carving a unique career for himself as a construction specialist, focusing on building performance (hence the additional affix Dip BP after his BSc/BArch and RIBA).

I spent a day with him in January at Ward's factory in Sherburn, North Yorkshire, where he is collaborating with Frank Atkinson of Ward on a research programme into the performance of industrial and commercial cladding systems. Atkinson started as 'a lad on the drawing board' with Frank and Wilf Ward, who founded what is now the UK's largest manufacturer of profiled metal cladding.

His first task is as one of a three-man team formed to 'conceive, design and develop' an alternative purlin system to the 'Z' profile.

Ward has always had an enterprising spirit, and its inventive and adventurous ethic is still evident today, with Frank Atkinson talking of Ward as a company intent on 'driving the industry forward'.

Hence the link with Stuart Borland's company, 'Building Sciences', which Ward has commissioned for this study.

Their joint work could have far-reaching implications, as it co-ordinates the extensive reviews under way on the comparative performance of conventional twin-sheet systems (liner/quilt/outer sheet as used on virtually all modern warehouse and factory buildings) against insulated panels where the rigid insulation core is bonded to the inner and outer sheets.

Ward's ambition is to shift the entire construction industry from its current 80 per cent usage of the old-fashioned built-up system to the safer, high-performance insulated panel arrangements. Its argument is compelling - and revealing.

Consider this. The steady increase in thermal performance demanded by the building regulations (0.45 W/degreesCm 2since 1990 and 0.6 from 1986) has led to an ever greater thickness of mineral fibre within the cavity of the built-up system but - and this is the irony - a possible consequent fall-off in insulating performance which is entirely self-defeating.

Borland's thesis runs thus: thicker insulation can lead to greater condensation through night-sky radiation as the outer sheet, isolated from the building's heat, becomes comparatively much colder.

Condensation which forms on its underside may then soak the quilt, especially where breather papers are omitted, despite the recommendations of BRE Report 262. The quilt performance then deteriorates until a stable condition arises where the consequent greater heat loss warms the outer sheet, thus reducing the effect of night-sky radiation. In these circumstances, the 80mm quilts needed to achieve the 0.45 U values can under-perform drastically - Borland reckons possibly well short of the old 0.6 standards introduced by the 1986 building regulations!

Result? Thermal efficiency within the built-up cladding systems that currently dominate the market may actually be in decline despite the increased thickness of quilts introduced to meet the new building regulations.

Add to this the further problems arising from constantly saturated insulation, and a micro-climate that is almost certainly causing deterioration to the building fabric, and it is clear, if Borland and Atkinson are right, that property owners and facility managers could be facing serious failures.

That's why Frank Atkinson is so interested in educating professionals, developers and contractors on the merits of the alternative insulated panel systems for industrial and commercial buildings.

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