- Environmental Sustainability
- Natural element
- Sustainable resource
- Natural and maintanance-free surface
- Long service life
- 100% recycable
- Secured recovered material cycle
- Low primary energy use
- Natural Element
Zinc is one of the top ten elements in the earth’s crust. Zinc comes second as a main trace element behind 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 ore is available on a large scale from the geological as well as the geographical aspect and is mainly mined underground worldwide. Currently, the most important ore mining areas are in Australia, Canada and Peru. But there are also important zinc ore producers like China, Japan, Mexico, Zaire and some European countries. 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 this would be a reserve for the next 700 years. In this context, the share of recycling material has not been taken into account. Thus, zinc does not belong to the limited resources.
Natural and maintenance-free Surface
The products of the PATINA LINE have a natural surface and no permanent coating or phospate layer. They do not need any maintenance or regular cleaning intervals. Over time a blue-grey or graphite-grey protective layer forms – the so-called patina. The self-healing properties of this patina are particularly important as they make scratches invisible over time.
Long Service Life
The so-called industrial zinc was already used by the famous architect Carl Friedrich Schinkel in the 19th century. The buildings designed by Schinkel (1781–1841) are now refurbished by and by – unless they hadn’t fallen victim to the destruction of the last World War. This fact alone shows the durability of construction zinc as weather protection.
The patina is responsible for the corrosion protection and the durability of the material. The water-insoluble layer is permanently removed by environmental influences / erosion (both natural and harming environmental influences) and simultaneously the material forms a new patina.
Due to the significant reduction of environmental pollution during the past decades the corrosion rates, which also depend on the location, 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 corrosion rate. According to latest studies this value has to be considered rather to be too high than too low.
If the corrosion 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. If other influences, like e. g. processing are taken into account, a realistic life expectancy of about 100 to 120 years can be assumed for RHEINZINK roof coverings. A proper planning and a flawless processing are vital for reaching the above-mentioned life-expectancy.
The following institutes and certification bodies confirm 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 expectamcy of 50 years (Source: Table “The service live of building elements for the life-cycle analysis 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 Institute TNO (Built Environment and Geosciences), Breda, Netherlands assumes a service life of minimum 75 Jahre for gutters and downpipes.
Recyclability plays an important role in the field of sustainable building. The demolition process belongs to 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. Therefor construction materials should be used which can be re-used or recycled.
Principally, RHEINZINK products last forever. In case of refurbishment or at the end of its service life a trouble-free separate collection is possible. All products of the 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 processed into new products. In Germany, the recycling rate for construction zinc stands at more than 95 % – consequently almost no construction zinc gets lost. Today, thanks to the high recycling rate almost one third of the material consists of recycling material – 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 compared to primary production. Considering the economic aspect that scrap metal can nowadays fetch as much as 60% of the price charged for high-grade zinc as a raw material the decision for the natural material also is extremely sustainable.
Low primary Energy Use
Thanks to low melting temperature compared to other metals of approx. 520° during production and the recycled content RHEINZINK products have a low primary energy content. They can easily bear comparison with other building metals or conventional roofing materials like concrete or clay tiles.