4 May 2018

How to choose sun protective fabrics

Knowing and comparing the features of fabrics allows you to choose the level of sun protection you need to get the best thermal and visual conditions indoors. Here are some of the features you may want to check.

For those who are considering buying awnings to prepare for the summer and getting energy-efficiency tax credits, it’s good to know that not all awnings are the same. The only ones that are effective for sun protection are those installed on the outside of the glass, as they keep the radiation from entering the room.

Indoor curtains, on the other hand, are excellent furnishing accessories and are perfect to adjust daylight and to protect your privacy. These include Pronema technical fabric curtains (Soltis, for example) and tailored curtains from the Doro collection.

It is important to make sure that the fabrics and their supporting structures are CE-certified and are accompanied by their use and maintenance manual.
 Outdoor awnings can be made of acrylic, polyester or cotton fabrics. Bulk-dyed synthetic fibres ensure stability and durability, as well as good protection in any weather conditions. If you live in a windy area, you may want to check the wind resistance class, which ranges from 1 – the minimum performance level – to 3, which offers greater tear resistance.
Natural fibres like cotton are more prone to damage and sensitive to moisture which, if kept wound up for a long time, can facilitate the accumulation of dirt and mould growth. In addition, cotton tends to fade with age and long exposure to sunlight.

For a good balance between thermal and visual comfort, you need to stop the radiant energy from the sun without hindering the view of the outside and the passage of natural light. This is something you should take into account in any case, but above all at work and in schools because of their beneficial effects. Sunlight stimulates the production of serotonin and vitamin D, and as a result it promotes well-being, good mood and productivity.

Awnings, such as folding-arm or canopy awnings, meet these requirements effectively, provided that they are designed to protect south-west, south and south-east facing windows.
For roller blinds installed parallel to glass surfaces – such as the Cento or Extralarge blinds in Pronema catalogue, for example – make sure you check the luminosity and thermal resistance of the glass, as well as the following two characteristics:

  • the fabric transparency alpha value which indicates the level of transparency of the material and should be approx. 5%;
  • the SR (Solar Reflection) factor, which identifies the quantity of radiant energy absorbed by the fabric and should not be less than 65%.

A thick weave, with a low opening factor, indicates greater shading from sunlight, but also reduced visibility. The latter is expressed by the VT (Visible Transmission) parameter, which quantifies the percentage of light filtered by the fabric and should not exceed 25%.
Screen fabrics in light and semi-transparent colours, combined with classic double glazing, provide effective shading from the sun, reducing indoor temperature by 2 to 4 degrees while preserving sufficient light transmission.

The current energy efficiency regulations for buildings require that shading systems, in addition to the characteristics of the glass, should block at least 65% of sunlight. The gtot parameter, which is required to apply for tax credit in Italy, must be less than or equal to 0.35. This value is equivalent to at least a Class 2 performance level.

Pronema offers numerous solar shading systems which improve living comfort and the perception of wellbeing and perfectly match the style of any classic, traditional or modern building. All devices and technical fabrics are certified to guarantee quality, durability and high performance.


Posted by Alessandro Palazzo
​Architect. A ClimateHouse energy consultant who specialises in improving the energy efficiency of buildings. He is a professor at the Faculty of Design at Politecnico di Milano. Since 2010, he has been a European Commission consultant at the Joint Research Centre in Ispra (Varese).

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