The HSA cover this in the following
Is there a maximum temperature for an office?
This is covered by Guidance Section 7 of new General Applications Regulations 2007.
There is no maximum temperature stated under the regulations but as a guideline a minimum comfortable working temperature for indoor sedentary workers is 17.5 degrees centigrade. In extremely hot weather conditions, measures such as for example, the provisions of fans, provision of cold water dispensers and regular water breaks for staff, the relaxation of formal dress codes, the introduction of flexible working patterns etc., can assist in maintaining comfortable working conditions.
In addition, each enclosed workplace must be adequately ventilated. In most cases the natural ventilation provided through windows and doors will be adequate. However in some cases forced ventilation may be required.
See the Guide to the 2007 General Appliclation Regulations for details.
Windows, skylights and glass partitions in offices must be so arranged as to prevent the excessive build up of temperature at workstations from excessive sunlight.
Is there a requirement for Employers to provide air conditioning?
There is no requirement on Employers to provide air conditioning or mechanical ventilation to provide ventilation however Section 2 of Schedule 2 of the General Applications Regulations states
(1) Steps should be taken to ensure that there is sufficient fresh air in enclosed places of work, having regard to the working methods used and the physical demands placed on the employees. In most cases this would be natural ventilation, it could include windows, doors, local fans etc.
(2) Where a forced ventilation system is used, it shall be maintained in working order. If an air conditioning system is installed then it must be adequately maintained. To look at it another way we cannot insist that a company install air conditioning but if they have installed it then we can insist that they maintain it so that it operates correctly.