Self-cleaning glazing products: A state-of-the-art review and future research pathways

Abstract

Self-cleaning technology is used in a variety of products today, with glazing products being the foremost area of application. However, there are several self-cleaning technologies in use and their self-cleaning efficiency may be unclear. This study aims to give a comprehensive state-of-the-art review of the self-cleaning glazing products available on the market today and investigate methods for measuring the self-cleaning effect. Various future research pathways and opportunities for the self-cleaning products of tomorrow are also explored within this study, with emphasis on solar energy application areas such as daylight, solar radiation transmission, electrochromism, building integrated photovoltaics (BIPV), solar cell glazing and solar cells in general. Self-cleaning products from several manufacturers that utilize two different self-cleaning technologies of either photocatalytic hydrophilic or hydrophobic capability are presented. The photocatalytic hydrophilic products in question are self-cleaning glazing products ready-to-use when purchased, whilst the presented hydrophobic products are coatings that must be applied to existing glazing products in order to yield a water-repellent and self-cleaning surface. It is stated that the self-cleaning action of the photocatalytic hydrophilic products is evident through 25 to 30 years, even during dry spills, and that they are able to maintain a cleaner surface than ordinary untreated float glass. However, the selfcleaning action of hydrophobic-coated products is limited by a relatively short life expectancy of about 3-4 years, and their self-cleaning performance is found to be feeble compared to ordinary untreated float glass. Nonetheless, the potential for future use of both self-cleaning technologies are apparent, with focus on alternative application areas such as solar cells, BIPV and information display devices, which indeed could benefit from utilizing the selfcleaning technology. Visions for future self-cleaning products are also discussed, which combine self-cleaning abilities with photovoltaism and electrochromism, whereupon the applicability of the self-cleaning technology may be greatly increased.

Thin Films for Advanced Glazing Applications

“…Some experts appoint that the development of strong transparent materials is the future in the glazing industry. These materials could be strong enough to replace frames in windows and used in spacers at the same time that allow light go through [25].…”

“…However, the maintenance of this technology can be expensive, and this is where self-cleaning technology will prove very useful, as the accumulation of dirt affects the performance of photovoltaic cells. Thus, the integration of self-cleaning technology in solar glazing is highly desirable [25]. There is a drive to develop new materials that have strong mechanical properties and great absorbance in the ultra-violet and, partially, in the visible spectrum to enhance photocatalysis.…”

The challenge of removing snow downfall on photovoltaic solar cell roofs in order to maximize solar energy efficiency—Research opportunities for the future

“…Chabas et al [9] have investigated the behaviour of self-cleaning glass in an urban atmosphere. Also note the study by Midtdal and Jelle [53] on self-cleaning glazing products where a state-of-the-art review has been presented along with future research pathways. Figure 16.…”

“…Commercial self-cleaning products may according to their operational state when purchased be divided into the following two categories (Midtdal and Jelle [53]):…”

Titania‐based photocatalytic coatings on stainless steel hospital fixtures

“…It is not known if TiO 2 applied by these methods has PC activity. Current self-cleaning TiO 2 coatings are applied to glass by atmospheric pressure MOCVD using titanium isopropoxide (TTIP) [15]. There are no MOCVD processes reported in the literature or available in industry currently applying thick (>10 µm) TiO 2 coatings to complex shaped metal parts.…”