Screen fabrics are always one of the most popular choices for roller blind fabric in both the commercial and residential sectors.
Screen fabrics are effective at reducing glare and harsh light, whilst still providing the user with a view out of the window and access to natural daylight. This survey from Harvard Business Review shows that one of the things employees most want in their workplace is daylight. That means choosing the right fabric for every application is vital.
Sunscreen fabrics are available from multiple fabric suppliers, and come in a huge variety of colours and opennesses. The openness factor is expressed as a percentage and indicates how open the fabric weave is.
Many screens, such as our Spectrum 5010 fabric, are available in a 1%, 3%, 5% and 10% openness. However there are some speciality screens which come in 2%, 4% and 25% openness, so there are options available for almost any requirement.
One thing that we find often gets overlooked when it comes to screen fabrics is the colour. We often receive job specifications which have listed every specific requirements the project manager has for the blind system and fabric type, but the colour is left as ‘tbc’.
This is usually because the colour is seen as a non-vital aspect of the blind that can be decided on further down the line by designers. However, the colour of a screen fabric can have a massive impact on its performance and ability to reduce glare.
‘TRA’ Values and What They Mean
Take a look at the table below for example. This shows the Solar (heat) and Optical (light) ‘TRA’ values for our Spectrum 5030 3% openness fabric in each colour way.
‘TRA’ stands for;
T- Transmittance i.e. how much light and heat gets through the fabric
R- Reflection i.e how much light and heat gets reflected by the fabric
A– Absorption i.e how much light and heat gets absorbed by the fabric
If you compare the optical TRA values for the white fabric to the black fabric, you’ll see that the black fabric is much better at absorbing light coming through. White fabric may be more reflective, but it’s also massively less absorbent which means a lot more daylight comes through. This essentially turns white fabric into a light source in itself.
This means you end up being able to see less out of the window, which is a large part of the reason why screen fabrics are requested in the first place. You can see this in practise in the image below. Both blinds are fixed in front of light boxes, and you can see instantly that the black fabric is letting less light through whilst still allowing a better view out.
There are benefits to using a white screen fabric, with the main one being that white fabric is better at reflecting heat than darker fabric. If you look back at the TRA diagram above and compare the Solar values, you’ll see that the white fabric has a reflection value of 70%, compared to the black which has a 3% value. This means that the white fabric is reflecting 67% more heat away from the window than the black fabric is.
To allow you to have the best of both worlds, you could consider a silver-backed screen fabric. These fabrics look like a standard screen on the front, but the back of the fabric has a highly reflective metalised backing which reflects massive amounts of heat.
If you choose a dark coloured, silver-backed screen fabric you can have a view out with the added benefit of heat reflection. Generally speaking, TRA values on metalised screen fabrics are fairly consistent across the whole colour range. Check out our Spectrum 4060 3% metalised screen fabric here.