Controlling thermal comfort
There are a number of ways that you can control thermal comfort in the workplace, some of which are very simple.
There are six main control methods you can use:
Control the environment
- replace hot air with cold, or replace cold air with hot, as required
- humidify or dehumidify the air as required
- increase air movement by ventilation or air conditioning
- reduce draught discomfort by directing the ventilation or air movement so that it doesn't blow directly onto the employees, eg using baffles
Separate the source of heat or cold from the employee
- erect barriers that shield or insulate the work area or restrict access
- redesign jobs to remove the employee from the area
Control the task
- restrict the length of time that employees are exposed to hot or cold conditions
- control the amount of work and rate of work employees are expected to do
- introduce mechanical aids (eg lifting aids or power tools) to assist physically demanding jobs in warm and hot environments or when employees are wearing a lot of clothing
Control the clothing
- if PPE is worn, make sure that employees are not wearing more PPE than is appropriate (ie a higher protection factor than is needed)
- if uniforms are worn, evaluate alternative designs, new materials etc to improve the thermal comfort of clothing
- evaluate dress code and allow employees to adapt their clothing where possible
- multiple layers of clothing enable employees to make reasonable adjustments to their clothing based on their individual needs
Allow the employee to make behavioural adaptations
- where possible, remove all restrictions that may prevent employees from making minor adjustments to their clothing or work rate
- provide warm-up or cool-down areas
- provide personal heaters or fans
- allow employees to adjust thermostats or open windows as appropriate
Monitor the employee
- provide appropriate supervision and training
- obtain medical advice from an occupational health professional for employees who are pregnant, have an illness or disability, or are on medication
- your risk assessment should already address risks to pregnant employees, but you may choose to review it when an employee tells you she is pregnant, to help you decide if you need to do any more to control the risks
Administrative controls include planning and rescheduling work times and practices and rest schedules, for example, scheduling ‘hot’ work for cooler times of the day or allowing employees to have flexible hours to help avoid the worst effects of working in high temperatures.
Administrative controls are generally of a short-term, temporary nature. Although some can be of a permanent nature, for example, emergency procedures and the provision of appropriate welfare facilities, such as competent first aiders with additional knowledge in the management and recognition of heat-related illnesses and injuries as well as ensuring the availability of appropriate first-aid equipment.
These should be the first choice to reduce or eliminate the hazard. Although the initial cost of engineering controls may seem high, it has been found that the implementation cost is often offset by the resulting improvements to production.
Any practical solution to controlling thermal comfort is likely to require a combination of different options developed in consultation with employers, employees and their representatives.
Many types of heating systems are available:
- hot air-based heating systems
- water-based central heating systems using radiators
- combined heat and ventilation systems using air conditioning systems
- electrical heating systems using electrical heaters
- under-floor heating systems using either electrical coils or heated fluids
- overhead heating systems
Most of these systems are useful. However, the beneficial effects may be restricted in some situations to the immediate locality of the heat source.
There are many methods for increasing air movement, ie fans of various sizes (but may cause draught or noise problems).
Large diameter ceiling fans can provide air movement that is effective over a wide area. Large exhaust fans, mounted in roofs and walls, are useful for removing heated air and drawing in cooler air from outside.
This can range from small units that lower the air temperature but do not control humidity levels or air movement, to large units that can cope with extreme conditions as well as humidity and air movement.
When air conditioning systems are used, take care to ensure uniform air distribution throughout the workplace, otherwise some employees may complain of feeling cold while others are feeling hot.
Air conditioning units should be operated as per the manufacturer’s instructions.
Evaporative coolers produce a moderate reduction in air temperature and increase humidity. They operate by passing hot air over water-saturated pads and the water evaporation effect reduces the air temperature.
There are many different types of thermal insulation materials, eg loose fills, rock wool and insulation boards. The material acts as a barrier, which slows heat flow in the summer and heat loss in the winter, but it is only effective where there is a temperature difference between the inside and the outside of the building or between two areas inside a building.