Choosing Blind Fabric for Performance

Fabric choice is about much more than just aesthetics. Engineers, architects and other building designers understand that high performance fabrics can have a significant impact on the Total Solar Energy Transmittance, Solar gain (gtot) and therefore BREEAM and LEED scoring systems for light pollution, thermal comfort and energy performance.

A key objective for most building designers is to reduce energy consumption whilst avoiding problems of solar heat gain and glare. Knowledge of the solar and luminous characteristics of fabrics therefore becomes imperative. Other concerns include maintenance and fabrics being affected by issues such as mould and staining.

When using retractable fabric to shade a building, the fabric must deliver the intended design aesthetic whilst also striking the right balance of performance and allowing views to the outside. There may also be other specific requirements for a project such as privacy, insulation values, light pollution restrictions or concerns around thermal glass breakage.

There are hundreds of factors which may require consideration depending on the design context and performance specification. And there are literally thousands of technical fabrics on the market. So, it can be confusing knowing where to start.

There is no replacement for carrying out solar shading analysis on a building’s design, including simulating the effect of environmental structures, during all seasons and times of day. The resulting analysis will help determine the performance parameters required of the shading system, to meet the objectives of the building. This then allows for the most efficient fabric to be selected, based on its performance and characteristics.

A fabric’s characteristics include openness of weave, transparency, colour and innovative materials:

• Openness – Fabrics are manufactured with a variety of openness, graded in percentage scores. A 5% openness factor means that 95% of the fabric is closed. The tighter the weave, the more solar heat gain protection the fabric provides.
• Transparency and colour – Transparency is regulated by openness but it is also determined by the colour of the yarn, and fabric.
• Innovative reflective or environment resistant materials – High performance metallised fabrics have been engineered to provide the highest standards of visual and thermal performance and are available in a both light and dark room-side colours. This gives the highest performance in terms of reduced Solar Gain, and the best glare control, without having to select a dark internal colour. Light-coloured internal fabric can also reduce glare if specified correctly. For fabrics which require specific resistance from their environment, such as humidity, sea air and chemicals, there are specialist coatings and treatments which can be applied.

Analysts can calculate the thermal and visual performance each fabric will achieve within a specific building dependent on its location, and engineers meticulously test a wide range of fabrics for thousands of cycles in extreme conditions to ensure lasting performance.

--Guthrie Douglas Group Limited

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