Photocatalytically active construction materials and surface coatings can help reduce nitrogen oxides in urban centres affected by pollution. Standards already exist in Europe for measuring photocatalytically active effects, but uniform quality standards for photocatalytically active products are still lacking. Wishing to give consumers and users in Germany an overview of the functionality and efficacy of these products, the FAP member companies decided for a voluntary commitment. The goal of this commitment is to contribute to sustainably ensuring good air quality and to improve transparency for consumers.
Together with scientists from several Fraunhofer institutes and universities, the FAP members have defined a measuring method for photocatalytically active construction products and a threshold for their NO degradation performance. The relative photocatalytic efficiency (rPCE value) is the unit for product assessment. The rPCE value is determined in a standardised and recognised process according to ISO 22197-1, referring to the degradation of the noxious gas nitrogen monoxide (NO). Products for photocatalytic air purification that reach an rPCE value of at least 2 – and thus have an air- purifying effect protecting health and environment – qualify for this product claim:
“photocatalytically active for air purification according to the FAP voluntary commitment”
When measuring product samples is should be noted that the construction materials sector comprises many photocatalytically active products that can show differences regarding the materials as such, manufacture and function. For an adequate approach to the different materials, the FAP identified the following 4 product groups and developed specific rules for sample preparation for each of them:
- Roofing tiles & ceramics
- Paints & coatings
- Mineral plasters
- Cement products
The product samples should be brought a defined state that corresponds as far as possible to the state of the product when used. Furthermore, contamination with unwanted substances should be kept low. Therefore, the instructions cover sample preparation, cutting, storage and pre-conditioning – always taking into account existing standards.
These detailed, product-based instructions for sample preparation are so far unique for photocatalytically active construction materials, and they are already included in research projects and international standardisation work.
The integral text of the FAP voluntary agreement (status 02/2017) is available here.