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CIBSE - TM59: Design methodology for the assessment of overheating risk in homes

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This technical memorandum released by the Chartered Institution of Building Services Engineers (CIBSE) provides a domestic overheating risk assessment methodology. It can be applied to dwellings, care homes and student residences. The methodology is intended for use by designers in order to influence building design for the better. It could be used at the planning stage to assess risk, as well as at later stages of design.


Contents include:



  • About the methodology
  • Clarifications
  • Basis of design comfort criteria
  • Implications of applying the methodology

The methodology


  • Identification of risk
  • Methodology overview
  • Suggested reporting requirements



  • Sample size
  • Weather files
  • Window and door openings
  • Exposure type
  • Infiltration and mechanical ventilation
  • Air speed assumptions
  • Blinds and shading devices
  • Pipework, heat interface units (HIUs) and heat maintenance tape heat loss
  • Communal corridors

Compliance criteria


  • Definitions
  • Criteria for homes predominantly naturally ventilated
  • Criteria for homes predominantly mechanically ventilated
  • Adjustments for homes with vulnerable occupants
  • Corridors: assessment criteria

Internal gains profiles


  • Occupancy and equipment
  • Lighting
  • Gain profile tables and charts

Supplementary information on profile development

To download the document, please visit the relevant CIBSE webpage at the link below.