Pitched roof coverings 3: Metal: Steel

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

   
stainless steel roof
   
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

Pro

Recyclable

Pro

Recycled content (approaching 100% in UK) 5

Pro

High material efficiency (4kg / m2) 5

Pro

Durable - ss is inherently corrosion-resistant

Pro

Does not leach to rainwater

Con

Very high embodied energy

Con

Emissions associated with fossil fuel energy production including SO2 and NOx

Con

Permitted emissions associated with production

Thermal conductivity

29 (5% Ni) - 16 (20% Ni) W/mK (1)

Density

7850 - 8000 Kg/m3

Embodied energy

37.5 MJ /kg (or 150 MJ/m2) - figure assumes recycling ratio of 0.96 (7) (figures source: How to quantify the environmental profile of stainless steel - Fujii & Nagaiwa, 2005 )

Life expectancy

60+ years

 

 

References


1 Inventory of Carbon & Energy (ICE) - Version 1.6a - Hammond & Jones, Univ Bath
7 How to quantify the environmental profile of stainless steel - Fujii & Nagaiwa, 2005

 

 

 

Disclaimer

GreenSpec accepts no responsibility or liability for any damages or costs of any type arising out of or in any way connected with your use of this web site. Data and information is provided for information purposes only, and is not intended for trading purposes. Neither GreenSpec nor any of its partners shall be liable for any errors in the content, or for any actions taken in reliance thereon.