Life Cycle Assessment - The Whole Story: From Cradle to Grave

It highlights the shortcomings of most current embodied carbon calculations and encourages a more holistic approach.  This means an assessment of the full lifecycle of buildings and materials from Cradle to Grave, rather than a simplified Cradle to Gate method which only considers the energy used to the factory gate and ignores the later burdens and benefits.   

The image above and the notes below are extracts from the supplement illustrating what happens to a building's structural frame when it is demolished.  

CONCRETE
The great majority of concrete from demolition sites is crushed and used as sub-base or fill. This is downcycling rather than recycling, i.e. a secondary use which is not of the same value as the first.
Aggregates from demolition may be re-used in concrete production but its use is restricted both by rules governing maximum percentages allowed and also by supply, since the amount of aggregate that can be recovered for this purpose is limited. Where aggregates are re-used in concrete, new cement, the source of most of the CO₂ emitted in concrete production, is still needed.

TIMBER
Definitive information on what happens to timber waste following building demolition is difficult to find. Recent publications from TRADA indicate that up to 80% of timber waste in the UK goes to landfill.
Timber can be downcycled by diverting material from the waste stream for the manufacture of chipboard. However, problems with contamination in the waste stream in particular restrict opportunities to divert waste for re-use and recycling.

STEEL
Steel benefits from having a high intrinsic value supported by a well developed and efficient scrap collection infrastructure. It can be recycled at end of life to form products that are of the same, or higher, standard and quality as the original material and most steel components are large and easily captured.
Capture rates vary depending on the ease of extraction from the demolition site but are always above 90% and average 94% for all steel components. For sections, it is 99%.

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