Building Regulations Approved Document L2 - Conservation of Fuel & Power in Buildings

This Approved Document, which took effect on 1 April 2002, deals with the following Requirements which are contained in the Building Regulations 2000 (as amended by SI 2001/3335):

Buildings or parts of buildings other than dwellings

L2. Reasonable provision shall be made for the conservation of fuel and power in buildings or parts of buildings other than dwellings by

  1. limiting the heat losses and gains through the fabric of the building;
  2. limiting the heat loss:
    1. from hot water pipes and hot air ducts used for space heating;
    2. from hot water vessels and hot water service pipes;
  3. providing space heating and hot water systems which are energy-efficient;
  4. limiting exposure to solar overheating;
  5. making provision where air conditioning and mechanical ventilation systems are installed, so that no more energy needs to be used than is reasonable in the circumstances;
  6. limiting the heat gains by chilled water and refrigerant
  7. vessels and pipes and air ducts that serve air conditioning systems;
  8. providing lighting systems which are energy-efficient;
  9. providing sufficient information with the relevant services so that the building can be operated and maintained in such manner as to use no more energy than is reasonable in the circumstances.



  • Performance
  • Introduction to the provisions
  • Technical risk
  • Thermal conductivity and transmittance
  • U-value reference tables
  • Calculation of U-values
  • Roof window
  • Basis for calculating areas
  • Air permeability
  • Conversion between carbon and carbon dioxide indices
  • Special cases
  • Low levels of heating
  • Low levels of use
  • Historic buildings
  • Buildings constructed from sub-assemblies
  • Mixed use development


  • General
  • Alternative methods of showing compliance
  • Elemental Method
  • Standard U-values for construction elements
  • Thermal bridging at junctions and around openings
  • Maximum areas of windows, doors and rooflights
  • Trade-off between construction elements
  • Building air leakage standards
  • Avoiding solar overheating
  • Heating systems
  • Carbon intensities of centralised heating plant
  • General
  • Calculating the carbon intensity of CHP systems
  • Calculating the carbon intensity of community heating
  • Other methods of heating
  • Trade-off between construction elements and heating system efficiency
  • Space heating controls
  • Hot water systems and their control
  • Insulation of pipes, ducts and vessels
  • Lighting efficiency standards
  • General lighting efficacy in office, industrial and storage buildings
  • General lighting efficacy in all other buildings
  • Display lighting in all buildings
  • Emergency escape and specialist process lighting
  • Lighting controls
  • Controls in offices and storage buildings
  • Controls in buildings other than offices and storage buildings
  • Controls for display lighting (all building types)
  • Air conditioning and mechanical ventilation (ACMV)
  • CPR method for office buildings with ACMV
  • Methods for other buildings with ACMV
  • Whole Building Method
  • Office buildings
  • Schools
  • Hospitals
  • Carbon Emissions Calculation Method
  • Conservatories, atria and similar sun-spaces


  • Building fabric
  • Continuity of insulation
  • Airtightness
  • Certificates and Testing
  • Inspection and commissioning of the building services systems

Providing Information

  • Building log book
  • Installation of energy meters

Work on existing buildings

  • Replacement of a controlled service or fitting
  • Material alterations
  • Material changes of use
  • Historic buildings


  • Appendix A: Tables of U-values
  • Appendix B: Calculating U-values
  • Appendix C: U-values of ground floors
  • Appendix D: Determining U-values for glazing
  • Appendix E: Calculation examples
  • Appendix F: Meeting the lighting standards
  • Appendix G: Methods for office buildings
  • Appendix H: Methods for solar overheating

Source:   ODPM 

             (Crown copyright material is reproduced with the permission of the Controller of HMSO and the Queen's Printer for Scotland.)

For more information on this source please visit Office of the Deputy Prime Minister.

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