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Conclusion and outlook

The coating technology developed on a laboratory scale has been successfully transferred to larger, industrial applications. It is now possible to add mechanically stable and securely attached coatings with low-e properties to commercially available fabrics, membranes and foils and, at the same time, to give this material a colour appearance which can be freely chosen. Textile architecture with energy-efficient materials has significant advantages in non-residential buildings – these include: the covering over of large areas, allowing for use of daylight, high degree of preassembly, flexibility and cost-effectiveness.

Sun protection applications can be made more effective using low-e coatings for both moderate and for more southerly climate zones. The refurbishment of old buildings and the building of new homes could become mass markets for low-e materials. However, low-e fabrics are not in competition with energy-oriented façade refurbishment (which should always be viewed as the first option); instead, the two can actually complement each other. For a start, roofs can be provided for larger areas, thus lowering the weather-resistance requirements for the covered facades. In addition, membrane solutions are also possible in cases where other solutions are not feasible because of construction constraints or the limitations which apply to listed buildings. And finally, the combination of low-e fabrics with well-insulated facades is an attractive way of reducing condensation formation. In many of the application areas identified here, relatively short energy-related and financial payback times can be achieved by increasing energy efficiency.

The low-e coatings generally use carrier substances that are already in common use today in buildings and for which there are established recycling solutions. Researchers will investigate the practical use of low-e fabrics in existing buildings in the follow-on project “Membranes in the energy-oriented refurbishment of buildings”. Symposia and workshops will accompany the tests as part of the German Federal Ministry of Economics and Technology’s EnOB research initiative. In addition, an Internet platform will introduce the technology to potential users. The researchers also plan to focus on coatings for transparent and translucent materials. Apart from building construction and textile architecture, many other diverse areas of application exist, including the automobile sector, coated glass in solar receivers, and heat-resistant visors in fire-brigade helmets. Transparent coatings with a high reflectivity in the infrared spectral range can be manufactured using transparent conducting oxides (TCOs), for example. In particular, doped indium oxide (ITOs for short, from indium tin oxide) is well established as a low-e coating in other sectors, and has thus been selected for the initial experiments. However, ITO coatings are relatively expensive due to their indium content. It may be possible to develop an alternative using AZO (aluminium-doped zinc oxide), which is significantly less expensive.

The sol-gel process is to be used for applying the ITO or AZO coating. This produces significantly more resistant coatings as compared to conventional sputtered coatings. Use on the exterior of facades thus becomes possible, in a manner similar to coloured low-e coatings.

 

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