Offices: Temperature and humidity - what are the 'rules'?

Complaints about air-conditioning and heating in offices (and other workplaces) are very common - it is either too hot or too cold; the temperature varies drastically through the day; the draughts are terrible; etc. It's not only the temperature that affects how people feel, but also the humidity levels and air movement. There are no regulations specifying standards for minimum temperatures in the workplace, humidity or air-flow in Victoria.

However, both the employer and the person who 'manages or controls' a workplace have a duty of care under the Occupational Health and Safety Act, 2004 to provide as far as practicable, a working environment that is safe and without risks to health - and therefore should be doing something about unsatisfactory air-conditioning or heating. The employer also has the duty to monitor conditions at the workplace - this includes temperature.

The Compliance Code for Workplace amenities and environment covers this in a bit more detail, but is still not very helpful, stating:

"Workplaces that are buildings need to be capable of maintaining a temperature range that is comfortable and suitable to the work. Workplace temperatures that are too high or too low can contribute to fatigue, heat illness and cold-related medical conditions."

The code states: "Optimum comfort for sedentary work is between 20°C and 26°C, depending on the time of year and clothing worn."

In addition, the code has advice on ventilation, air quality and airconditioning (Sections 128 - 131).  More information - Hazards page on Heat (or for full text: Compliance Code for Workplace amenities and work environment)

So, are there Guidelines?

Generally, the temperature in offices should vary according to the outside temperature, and should be changed month by month. Mostly, it should be about 21 or 22 degrees, and it is suggested that this would be a good place to start. Adjustments should then be made from that point, checking that the air conditioning reaches all areas in the office, and that windows receiving substantial quantities of sunlight are not causing problems.

Recent research undertaken in the Netherlands (on building efficiency) found however, that women generally are more comfortable if the temperature is closer to 25 degrees C - about 3 degrees warmer than men. This too should be taken into account.

There is more information in the Australian Standard AS1668.2: The use of ventilation and airconditioning in buildings - Ventilation design for indoor air contaminant control. Australian Standards can be purchased on-line through the Standards Association shop website. Other contact details are also on the website. Local or educational institution libraries may have copies of Australian Standards, so check these.

Often the problem is that the air conditioning units need servicing, or that the rate and direction of air flow are unsatisfactory. The guidance booklet Officewise is now used by all jurisdictions and is available (free) from WorkSafe (03 9641 1555). It can also be downloaded from the WorkSafe website.

Officewise recommends the following to improve thermal comfort:

  • Regulate air conditioning for temperature and humidity; 

  • Avoid locating workstations directly in front of or below air conditioning outlets;

  • Install deflectors on air vents to direct airflow away from people. These measure will prevent staff being annoyed by draughts; 

  • Control direct sunlight (radiant heat) with blinds, louvres and the like;

  •  Minimise draughts and thermal differences between the head and the feet (thermal gradients);

  •  Ensure adequate air flow. Feelings of stuffiness can result when air flow is low, and draughts result when air flow is high. An air flow rate of between 0.1 and 0.2 metres per second is desirable.

Humidity

With regard to humidity, if it is too high this will cause discomfort (excessive perspiration, exacerbation of the effects of high temperature, feelings of 'closeness', etc) and if it's too low it can cause respiratory problems. Optimum humidity levels are between 40% and 60% - but in any case they should be kept between 30% and 70%. Humidity levels below 40% will begin to cause problems for workers with conditions such as sinusitis. (Advice:  from the CSA Standard CAN/CSA Z412-00 (R2005) - "Office Ergonomics" which gives acceptable ranges of temperature and relative humidity for offices in Canada. These values are the same as recommended by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) Standard 55 - 2010 "Thermal Environmental Conditions for Human Occupancy". )

Temperature/Humidity Ranges for Comfort

ConditionsRelative humidityAcceptable Operating
Temperature
Summer (Light clothing)If 30% then
If 60% then
24.5 - 28 °C
23 - 25.5 °C
Winter (Warm clothing)If 30% then
If 60% then
20.5 - 25.5 °C
20 - 24 °C

Source: Canadian Centre for Occupational Health and Safety - Adapted from ASHRAE 55-2010.

Advice for OHS reps

If people in your office are unhappy then the health and safety representative should approach management to request that the following things be checked:

  • whether the system is working properly or needs maintenance, adjustment etc;
  • the temperature in various places within the building (this can vary according to a number of things, including radiant heat, where the thermostats are located, etc);
  • air flow;
  • humidity; and so on.

This is a duty under Section 21(4)(d) of the OHS Act: "monitor the conditions at any workplace under the control and management of the employer". If necessary, the employer should bring someone in with the appropriate level of expertise - Section 21(4)(c): "employ or engage persons who being suitably qualified in relation to occupational health and safety are able to provide advice to the employer in relation to the health and safety of employees."

What if the air conditioning system breaks down?

The information (previously) found in Commonwealth Guidelines suggested that air conditioning systems usually deliver more than enough fresh air than is necessary for health. The Guidelines also suggested that a common sense approach when air conditioning systems are "off" is to evacuate affected parts of the building when the working conditions become unacceptably hot, cold or smelly.

With respect to air temperature, in a still office environment, there should be no adverse health effects (for normally healthy people) from working when the dry bulb air temperature (that is the inside thermometer) is within the range of 18 to 30 degrees Celsius. Outside of this range some staff may become affected and it is essential that corrective action be taken if staff are to remain in the building for other than short periods of time.

Experience also shows that outside the range of 20 to 26 degrees people will become uncomfortable and productivity is likely to drop.

Therefore in the situation where only part of the air conditioning is working, the indoor temperature should be monitored, and where the temperature exceeds 26 degrees, management should provide free standing ventilation fans as an interim measure until the air conditioning is fully functioning. There may be some other options in some situations, like working from home as a short term measure, but the emphasis should be on fixing up the air conditioner as soon as possible.

If the inside temperature goes above 30 degrees Celsius and staff are feeling unwell then measures must be taken to cool them down, and they should complete an incident form to document the situation. In some cases, depending on how they feel, staff may need to go home. In such a situation, where management has not been able to implement reasonable measures to address the OHS problem, staff should not incur any pay penalty.

Contact your union for information and advice in such situations.

See Also:

Last amended June 2016

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