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Considerations when deciding the best fabric for office blinds
Category: All
By: John James

Office blinds to cut out heat & glare

Whether you are an architect, interior designer or facilities manager it is easy to overlook the huge impact that blinds in offices have on staff productivity and well-being. As companies invest in improving their work space to attract and retain the best staff, it is critical to consider the effect that light and heat levels have on creating exceptional working environments. Cost wise, blinds are a relatively small component in any office fit-out project but play an important role in achieving optimum light and temperature levels. Add to this the shift towards floor-to-ceiling glazing and the role of blinds to reduce the effects of solar gain becomes even more important.

Roller blinds are by far the most popular blinds of offices. Roller blinds offer the greatest scope as far as high-performance fabrics are concerned, with the fabric options for vertical blinds being typically restricted to a few privacy fabrics. Venetian blinds are not recommended for offices – the solid slats have minimal heat reflecting properties, the slats create shadows on computer screens and attract dust.

There are three key issues to address when selecting fabrics for office blinds:

Glare
Heat
Through vision

Glare
The most obvious way to combat excessive glare in offices is to use a fully opaque fabric that blocks all light. Unfortunately, this also cuts out visibility to the outside world and increases the building’s reliance on electric lighting. Research shows that a human’s sense of well-being is increased if a connection with nature and the world outside is maintained. By cutting out all view of the world around productivity and health and well-being take a big knock. By relying on electric lighting the building’s carbon emissions and the occupier’s energy bill increase, threatening sustainability.

A dark screen fabric will absorb a high proportion of the light and, because our eyes focus on light rather than darkness, maintain a vision of the outside world. How do you know to what extent any particular fabric will reduce glare? Every reputable fabric will have a set of performance data to help you ascertain how effective they will be. Look at the amount of visible light transmitted (Tv%) by the fabric. A Tv% factor of less than 10% is recommended. For more help on understanding the performance data of solar shading fabrics read our blog. Dark colours will typically have a lower Tv% than light colours making them more effective at reducing glare.

A dark screen fabric, however, does little to address the next issue – heat.

Heat
The Sun radiates energy in the form of short-wave radiation – better known as light. When this energy is obstructed by an object i.e. a building, a person etc. it is re-radiated as long-wave radiation, known to us as heat.

Thus glazed curtain walling without some form of solar shading blinds becomes a giant radiator. Without effective blinds in offices, occupants must either struggle through it resulting in a drop in productivity and health & wellbeing, or the company must increase their reliance on air conditioning and accept the rise in carbon emissions and energy costs that ensue.

In order to reduce heat, a window blind fabric that reflects this energy back through the glass to the outside is required. Unfortunately, dark coloured fabrics that are effective at reducing glare absorb heat rather than reflect it. A light coloured fabric will help reflect heat back out of the window to reduce the amount of heat entering the room. To ascertain how effective a particular fabric will be at reducing heat, look for the ‘solar energy reflected’ (Rs%) figure. This will indicate how much energy the fabric will reflect back towards the glazing and away from the building interior. Light coloured fabric will typically have a higher Rs% value than dark colours. Again this is explained in more detail in our ‘understanding the performance data of solar shading fabrics for blinds’ blog.

Unfortunately, light fabrics do nothing to reduce the glare or as mentioned earlier help with the third issue: through-vision.

Through vision
Studies show that as humans, a visual connection with the outside world improves our sense of well-being and productivity. In addition, offices with prominent views of the city skyline fetch premium rental deals, so it is important to consider this sometimes-forgotten aspect when selecting blinds for offices.
The only fabrics that offer a view through are screen fabrics. When looking at a screen fabric’s properties, check to see what ‘openness factor’ they have. This will give an idea of how much of a view-through the fabric permits. Openness fabrics for roller blind screen fabrics range from 1% to 10%. Bear in mind that the more ‘open’ the weave on a screen fabric, the less effective it will be at reducing heat and glare. A 3% openness factor is considered the optimum openness factor which allows a degree of through vision whilst having a negligible effect on the fabric’s solar shading performance. Remember dark coloured screen fabrics are easier to see through than lighter colours as human eyes focus on light, which makes us look through dark fabrics to the light outside.

The dilemma of solar shading blinds
By now you’ll see how the three most important aspects of solar shading conflict with each other. To reduce glare you need a dark fabric, to reduce heat you need a light fabric and to maintain through vision you need an ‘open’ fabric that lets in both glare and heat.
Until recently the answer to this dilemma was to compromise with a grey screen fabric. This was considered dark enough to reduce glare, light enough to reflect heat with some openness to allow a view though.

The ultimate solution for office blinds
The advent of high-performance screen fabrics that have a highly reflective metallised backing has taken solar shading in offices to a new level. Fabrics such as Verosol Silverscreen remove the conflict between light and dark fabrics. The highly reflective backing on the fabric enables you to combine a low Tv% factor (reducing glare) and a high Rs% factor (reducing heat). At the same time as maintaining an openness factor of 3% or 4%. Watch the video on our home page that explains why metallised fabrics are soo effective.

The solar shading performance of metallised fabrics far exceeds conventional screen fabrics. Verosol Silverscreen can reflect up to 82% of solar energy entering a building through the glazing. Consider the impact this has on the lighting and air conditioning usage of a 40-storey office building with floor to ceiling glazing on all four sides and you can see why specifiers, interior designers, landlords and facilities managers are taking notice!

View a case study where Verosol Silverscreen has been used here.

To find out more about solar shading performance criteria click here.

About the author

John James Marketing Director