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This guidance relates to inside working environments

If the workplace is too hot the risks are:

  • concentration can be affected leading to mistakes
  • personal protective equipment e.g. lab coats may not be worn
  • windows may be opened in laboratories which may affect containment or fans used which may affect the functioning of any local exhaust ventilation eg fume cupboards, present

There is no maximum prescribed working temperature. The law says that during working hours the temperature, in all workplaces, inside buildings must be reasonable. 

HSE guidance suggests a minimum workplace temperature of about 16°C and if the work is physically demanding it can be as low as 13°C. These temperatures are not absolute legal requirements: the employer has a duty to determine what reasonable comfort will be in the particular circumstances.

The inside working temperature may become uncomfortable for a number of reasons including:

  • Mechanical cooling is inefficient or not in good working order
  • There is no mechanical cooling and ventilation is poor
  • Processes and equipment in the workplace add to the heat load
  • Windows facing the sun don’t have blinds or a reflective coating
  • The outside temperature is significantly higher than the norm e.g. 'heat wave'

Controlling thermal comfort - what can managers do?

As soon as you become aware of staff concerns or think there is a problem take action:

  1. Where fitted ensure that mechanical cooling mechanisms are repaired or serviced to ensure they are working efficiently. Report problems to the Estates Service Centre
  2. Buy a thermometer and record the temperature several times during the day in different parts of the workplace. This will identify where the problem areas are and where resources should be committed
  3. Identify staff who may be at increased risk e.g. employees who are pregnant, have an illness or disability, or are on certain types of medication. For advice contact Occupational Health.
  4. Consider implementing some of the following measures:
    • Introduce flexible working patterns e.g. start work earlier when it's cooler
    • Allow staff to work from home if there role permits
    • Allow staff extra time to take breaks in cooler locations
    • Move staff to cooler locations in the building
    • In low risk environments e.g. offices relax the dress code by allowing staff wear sandals, shorts and loose fitting clothes. NB these measures will not be appropriate in laboratory and workshop areas
    • Provide fans or mobile air conditioning units
    • Have blinds / reflective film fitted to windows
    • Keep blinds closed during hot weather



The law


RiskNET Risk Assessment Tool


Workplace (Health, Safety and Welfare) Regulations 1992




UCLs Work Life Balance Policy

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