Key issues
• Embodied energy - there's a wide scale of embodied energy from wood shingles at the low end of the range to aluminium at the high. The main energy components are those derived from manufacture and transport. As with other materials, sourcing a product in the UK (and close to site if possible) can dramatically reduce its embodied energy.
• Material efficiency - Selecting a material can be made more complicated once its efficiency is considered. For example in some circumstances it can be argued that a strong, lightweight material used over a large span can have a lower environmental impact than a heavier, more sustainable material once the degree of structural support is introduced into the equation.
• Durability - The longer lasting roofing material has a lower environmental impact.
Materials
Stainless steel
Though embodying high energy, stainless steel is renowned for its durability. Another advantage is the degree to which the new stainless steel contains a very high percentage of recycled, which in the UK approaches 100%.
Stainless steel is produced by melting steel scrap in the electric arc furnace, followed by refining. Alloying elements utilised, such as chromium and nickel, depend on the type of scrap used as well as from extra additions to the melt.
See also: Steel production & environmental impact
