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CPD: Environmental performance of lead sheet

This is the last of three CPDs sponsored by the Lead Sheet Association (LSA). Lead is often perceived as a heritage material. But its sustainability credentials are leading to it seeing a revival. This CPD explores the environmental performance of the material.

Previous CPDs from the Lead Sheet Association have covered the design and specification of lead sheet roofing, of lead sheet cladding and of rolled lead sheet. The LSA provides technical advice on the use and application of rolled lead sheet manufactured to BS EN 12588 and a wide range of leadwork installation courses, including QCF (Qualification & Credit Framework) Levels 2 and 3.

The LSA’s 203-page Rolled Lead Sheet, The Complete Manual is available through the association’s website, www.leadsheet.co.uk.

LSA

Part 1: Embodied carbon

Lead sheet

Embodied carbon of specific building materials is becoming more important as we strive to achieve more sustainable buildings. As part of the 2008 Climate Change Act, the government pledged to reduce carbon emissions by 80 per cent by 2050. To do this it is necessary to reduce the carbon emitted during the whole life-cycle of buildings, including that emitted during the processes of material extraction, manufacturing, delivery to site, construction process, maintenance and refurbishment, waste processing, demolition and recycling. These elements make up the ‘embodied carbon’ of the building. Reducing the carbon emissions of materials going into the building has an immediate effect on the overall sustainability of the project, while achieving carbon reduction through operations accrue over a longer in-use period.

Lead sheet has a relatively low carbon footprint of 0.7 to 1.7kg CO2/kg of material.

Used on a flat or sloping roof, lead has a carbon footprint of between 4 and 58kg CO2/kg of material depending on roof build up. This is lower than similar applications using copper, zinc or stainless steel. This is also the case when lead is used in cladding applications, where it has a carbon footprint range of between 30-64kg CO2/kg of material.

Part 2: The BRE Green Guide to Specification

Lead sheet

The BRE Green Guide is part of the BREEAM certification process. It is used to examine the environmental impacts of construction materials based on life cycle assessments. Data for building components is set out in a ranking system, from A+ to E, where an A+ rating indicates the best environmental performance or least environmental impact, and E the worst. Green Guide ratings cover the following issues:

  • Climate change
  • Water extraction
  • Mineral resource extraction
  • Ozone depletion
  • Toxicity
  • Waste disposal
  • Fossil fuel depletion
  • Eutrophication
  • Ozone gas creation
  • Acidification

Lead sheet has recently received new ratings in the BRE Green Guide. In most of the standard roofing and vertical cladding installations lead sheet has a BRE Green Guide rating of A+ or A

Part 3: Ecopoints

Lead sheet

An Ecopoint score is a measure of the overall environmental impact of a particular process, the larger the score the higher the environmental impact. The Ecopoint scoring method takes into account the following:

  • Climate change
  • Fossil fuel depletion
  • Ozone depletion
  • Freight transport
  • Human toxicity to air
  • Human toxicity to water
  • Waste disposal
  • Water extraction
  • Acid deposition
  • Ecotoxicity
  • Eutrophication
  • Summer smog
  • Minerals extraction

Like in the BRE Green Guide, lead also scores well when measuring Ecopoints. Depending on the form of roof or cladding system adopted lead will only generate between 0.5 and 0.66 Ecopoints. These figures mean that the effect of using lead on a project is of minimal impact on its environment credentials.

Part 4: Ecopoint scores, Green Guide ratings and embodied CO2 for lead sheet and equivalent products

CPD table

Click to enlarge the above table

Part 5: Recyclability and waste

Lead sheet

When environmental and construction sustainability of products is considered for building materials, lead sheet has been used on Roman buildings, medieval cathedrals and castles, being recycled and re-used time and time again.

Lead is one of the easiest metals to recycle and, due to its low melting point, requires very little energy to process for re-use.

During the construction process all waste from lead sheet can be re-used and it is fully recyclable at the end of its life. Reclaimed lead can be recycled into new products without the loss of any performance.

In the UK there is an established recycling programme in place for lead products. This diverts it away from landfill and back into the construction process. 

Part 6: Life cycle

Lead sheet

Lead sheet has a predicted life of 60 to 100 years. When used for flashing it will last about three times longer than alternative proprietary products, which usually have a life span up to 20 years.

This can bring significant carbon savings. These savings are not just made through the fact that it does not need replacing as often, but also because very few post-installation inspections and little maintenance are required for its upkeep. 

This also leads to reduced life cycle costs, meaning lead is cheaper over the lifetime of the building.

Over a 40-year period lead can be up to 50 per cent cheaper than man-made flashing products and over a period of 65 years it is almost 100 per cent cheaper.

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