Zinc’s natural patina will appear lighter when used in marine locations where the air contains chlorides (salt). Deposits will not be as visible on lighter blue-grey zinc. For esthetic reasons, it is recommended to clean the surface of the material with clean water (not seawater) at least twice a year in maritime climate zones, depending on local conditions. If the metal is scratched, scuffed, or fingerprinted, with time and exposure to wetting and drying cycles zinc will heal itself by re-patinating.
In areas facing multiple climate challenges, such as marine environments that are susceptible to wildfires, architectural zinc offers a noncombustible solution as it is also non-corrosive. Research from the Association for Materials Protection and Performance (AMPP) estimates the annual cost of corrosion to Canada at $51.9 billion.13
Along with zinc’s climate-resilient, non-corrosive performance, it also provides a long lifespan to support reduced-carbon sustainable design and operational goals. Reduced-carbon architectural zinc and other metal roofing materials have a lifespan of 100 years or more.
In Canada and the U.S., asphalt shingles are used on approximately 75 per cent of homes.14 The lifespan of an asphalt roofing is approximately 20 years.15 While the initial material purchase price of asphalt is less expensive, over the lifetime use of the roof, architectural zinc costs less.16
Replacing a roof is not only a material and labour expense, but it also disrupts the property’s operation and occupants, resulting in lost productivity. For example, rooftop photovoltaic (PV) arrays have a lifespan of approximately 25 to 30 years for residential homes, and longer for more robust commercial buildings systems.17 This means during a PV array’s lifetime use, one would need to replace an asphalt roof at least once, interrupting renewable solar energy power generation. A zinc roof provides a platform to mount solar panels without replacing the roof, and will outlast the PV array’s lifespan.
In addition to accommodating power-generation systems, gutters, and downspouts fabricated from architectural zinc offer decades of continuous use in rainwater collection and harvesting systems. Its run-off is non-staining and non-toxic.
During their many years of use, zinc building products do not rot, rust, or need repainting. No paint, varnish, or sealants are necessary. Architectural zinc products require very little maintenance, repair, or replacement, which further lowers their associated economic and environmental costs. At the end of its long life of use on a property, one can also recycle the zinc material.
Asphalt shingles are among the seven largest contributors to construction and demolition debris. More than 90 per cent of used asphalt shingles, equivalent to around 9.8 million tonnes (10.89 million tons), end up in a landfill every year. With oil as its primary component, asphalt shingles are especially harmful to the environment when discarded.14
Zinc is 100 per cent recyclable, without degradation to its performance properties. Sixty per cent of all zinc produced is still in use and 45 per cent of all zinc produced is recycled. Zinc in building and infrastructure represents the largest stock by far with high product-specific recycling rates. Globally, 95 per cent of rolled zinc sheet is recycled.18
The sustainable attributes and applications of architectural zinc products support criteria for several green building programs including Building Research Establishment Environmental Assessment Method (BREEAM) certification, the Green Globes system, the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) rating system, and the Cradle to Cradle Products Innovation Institute’s certification system.
Products that have earned Cradle to Cradle certification demonstrate: no release of any toxic substances during usage, deconstruction, and recycling; retainage of original properties without loss of performance; and re-useability as a new item of at least equal value.19
