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Green Guide 2008 ratings

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External Wall Construction

External Walls

External wall ratings are the same for the following building types:
Domestic, Health, Commercial, Retail, Industrial, Education

Functional unit for External Walls:
1m² of external wall construction, to satisfy current Building Regulations, and a U value of 0.3 W/m²K. Where relevant, the specification will also include an internal wall finish.

Variation for retail/industrial
1m² of external wall construction, to satisfy current Building Regulations, and a U value of 0.3 W/m²K.


Perhaps more than any decision facing the designer, the choice of the external wall specification is subject to the widest range of practical, economic and visual considerations, some of which may be beyond the control of the design team.

External walls can have a significant contribution to the impacts of the building. The external wall can also account for around 30% of building costs. External wall specifications include a diverse range of construction types and materials; it is therefore no surprise that a wide range of environmental impacts is exhibited with this element.

External wall specifications have been arranged into four generic groupings in order to make access to information easier. However, ratings are based on comparative performance across all the options, as set out below:

  • Traditional form of cavity wall construction
  • Rainscreen claddings
  • Cladding and masonry construction
  • Cladding and framed construction


Solid Concrete Block Densities have been assigned as follows:
Dense block/blockwork (≈1950 kg/m³)
Medium density block/blockwork (≈1450 kg/m³)
Lightweight block/blockwork (≈1100 kg/m³)
Super Lightweight block/blockwork (≈850 kg/m³)

BREEAM Schemes to which this element applies:
External Walls chart
View this as a full page (PDF file)

Please select the element type of External Wall Construction ratings you wish to review:

Blockwork Cavity Wall Rendered or Fairfaced Blockwork Cavity Wall Brickwork on Framed Construction
Rendered or Fairfaced Blockwork Cladding on Framed Construction Cladding on Masonry
Rainscreen Cladding Insulated Cladding Insulated Render Systems
Curtainwalling Loadbearing Precast Concrete Insulated Concrete Formwork
Cladding on Structurally Insulated Panels Render on Structurally Insulated Panels Rammed Earth/Chalk