- Natural element
- Sustainable resource
- Natural and maintenance-free surface
- Long service life
- 100% recyclable
- Secured recovered material cycle
- Low primary energy use
Zinc is one of the top ten elements in the earth’s crust. Zinc is the second main trace element after iron and plays an important role for numerous physiological and biochemical functions. Zinc regulates hormones, stabilizes the cell membrane, influences growth and plays an important role for nerves, eyes, skin, wound healing and the immune system.
Zinc is available on a large scale both geologically and geographically and is mined underground worldwide. Under consideration of the present technical mining standards the zinc ore reserves are estimated at 3.400 million tons throughout the world – based on the current production quantities there is a zinc ore reserve that should last for up to 700 years. This estimate does not include the percentage of zinc ore that has been recycled.
Natural and maintenance-free Surface
The products of RHEINZINK-CLASSIC and prePATINA line have a natural surface and no permanent coating or phospate layer. They do not require any maintenance or cleaning. Over time a blue-grey or graphite-grey protective layer forms – the so-called 'patina'. The self-healing properties of the patina are particularly important as they make scratches on the zinc invisible over time.
Long Service Life
The so-called industrial zinc was already being used by the famous Prussian architect Karl Friedrich Schinkel in the 19th century. The buildings designed by Schinkel (1781–1841) that have incorporated the use of zinc are only occasionally refurbished, and this is only as a consequence of having suffered severe damage during the Second World War. That the zinc used by Schinkel is still in such a good condition despite the damage shows the durability of construction zinc.
The patina is responsible for the corrosion protection and the durability of the material. The water-insoluble layer is removed by environmental influences and erosion (stemming from both natural and man-made environmental influences) and following this the material forms a new patina.
Due to the significant reduction of environmental pollution during the past decades, the wear rates (which also depend on the location of the zinc), the orientation and pitch of the surfaces have considerably decreased. For the central European climate a value of 3.0 g/(m²·a) respectively 0.4 µm per year can be assumed as the average wear rate. According to latest studies this value has to be considered rather to be too high than too low.
If the wear rate is considered in context with the so-called half-value thickness (e.g. 0.35 mm for 0.7 mm sheet thickness) the result would be a statistical life expectancy of several hundred years. However, this statement only represents a theoretical life expectancy. With proper design, fabrication and installation, a realistic roof life expectancy of 100 to 120 years can be expected and 150+ years for wall cladding.
The following institutes and certification bodies have confirmed the durability of our material:
- The German Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety: Zinc as a roof covering has a minimum life expectancy of 50 years (Source: The service life of building elements for the life cycle analysis is based on the Assessment System for Sustainable Building for Federal Buildings).
- The British certification body BRE (Building Research Establishment Ltd.) estimates a life expectancy of minimum 80 years for RHEINZINK in the context of life cycle assessment.
- The TNO Institute (Built Environment and Geosciences) in Breda, the Netherlands assumes a service life of a minimum of 75 years for gutters and downpipes.
Recyclability plays an important role in the field of sustainable building. The demolition process is part of the life cycle of a building and has to be considered separately. The main goals are the protection of natural resources and the avoidance of high waste rates. An excellent recyclability guarantees the recycling of the parts of the building within the natural energy and material cycle. Therefore construction materials which can be re-used and recycled must be.
Crucially, RHEINZINK products last forever. In the event of refurbishment, or at the end of its service life, a trouble-free separate collection is possible. All products of the RHEINZINK-CLASSIC and prePATINA Line are 100% recyclable without additional production processes like the removal of coatings or separating composite materials. The scrap resulting from production is re-melted and is processed into new products. In Germany, the recycling rate for construction zinc stands at more than 95% - consequently almost no construction zinc is wasted. Today, thanks to the high recycling rate almost one third of the material consists of recycled matter – the rate is only limited as to the durability of zinc products.
The energy consumption for recycling RHEINZINK is only 5% of the primary energy content. This means that 95% of the energy can be saved in comparison to primary production. Considering that scrap metal can nowadays fetch as much as 60% of the price charged for high-grade raw zinc, the decision for the natural material also is extremely sustainable.
Low primary Energy Use
Thanks to both a low melting temperature of approximately 520°C during production and having a percentage of recycled content, RHEINZINK products have a low primary energy content. They can easily compete with other building metals or conventional roofing materials like concrete or clay tiles.
Please see our Environmental Product Declarations.