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Made in the shade

Louvres and brise-soleil are becoming increasingly popular as office occupants seek to hide from the glare of the sun

The brise-soleil is in. Ten years ago, people did not seem to mind squinting, pulling down the blinds, moving their seats or basking in the all-tooinfrequent sunshine; nowadays, you can't seem to pass a commercial building without seeing a forest of louvre blades. Take Foster and Partners' Scottish Gas Headquarters in Edinburgh.

This 10,500m 2building, engineered by Battle McCarthy, has received an 'excellent'BREEAM rating.The small matter of its glazed facade being drowned in silver-coloured tubes set at unequal centres, is seldom mentioned.

These brise-soleil have been fitted to all elevations, even the north face, which seems to go against the normal diurnal environmental requirement for these things. Secondly, the rounded cross-section of the blades, as opposed to the traditional aerofoil-shape does little to block the sun at certain points in its trajectory.As a trellis for climbing plants, it is a great sunshade.

Meanwhile, a 'new' product - that has effectively been around for 60 years in America - is coming to a window near you and could revolutionise, in terms of simplicity and cost, the way that we sunshade our buildings.

KoolShade louvres are woven bronze mini louvres. No longer 150mm thick aerofoils, these louvres are 1.27mm in width, and just 0.18mm thick spaced at about seven to eight per cm. The microblades are tilted nominally at 30infinity to the horizontal, held in place by two bronze wires knotted above and below each louvre wire. This mesh is then contained within an anodised aluminium frame and fixed to the window frame or surround. This format is ideal for retro-fit projects but there is vast scope for innovation.

In comparison with other materials, the mesh is an efficient device at reducing glare and heat gain. The company manufacturing it in the UK says that at 52infinity north (London) on an April morning when the sun is at 40infinity elevation, using this screen the mesh will cut out direct light altogether by 9am for the start of work. As the sun climbs to an even higher altitude during the day, glare will be eradicated until about 5pm, when the sun sinks again below 40infinity elevation.

Even at total cut-off, American tests show that the daylight factor at a given point is about 50 per cent, compared with 32 per cent with (non-perforated, opaque) Venetian blinds and about 35 per cent with tinted windows. The mesh is also sufficiently fine to allow reasonable views out for occupants.

Its primary function is as an aid to reduce solar glare and it fares extremely well at benefiting the comfort levels of occupants, compared to the conventional alternatives (see table).

At the moment, the manufacturer can cut the panels to suit any shape and is working towards a new UK testing regime. By offering the mesh and frame in any RAL colour, architects opting for this solution may be able to replicate a tinted appearance at a fraction of the cost and, on the back of contemporary results, provide a greater comfort benefit by reducing heat gain by a factor of four in comparison.

This material has been used on anything from listed buildings to the refit of the Mirabella V (the biggest sloop in the world).Using KoolShade as a wind/ rainscreen (it has low wind resistance [24.5kg/m 2] at wind speeds of 60mph and has been tested in windspeeds of 140mph) it is eminently suitable for use on high-rise buildings and those in exposed locations. Framed out, it could even be a full height envelope material on secondary framing, although additional stiffness needs to be considered to the mesh panels.

There seems to be a number of opportunities yet to be discovered.

Maybe an adjustable second layer of louvres could interfere sufficiently to act as a polarising filter. Who knows?

For further information contact Andrew Cooper on 02392 454405 or visit www. coopers-uk. com

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