Air conditioning and thermal comfort in Australian Public Service offices
PART 6 - Associated Documents & Sources Glossary of Terms
PART 1 - IntroductionThis information booklet has been developed jointly by the Department of Industrial Relations and The Community and Public Sector Union (CPSU) with assistance from Mr Paul Spry of Australian Construction Services (a division of the Department of Administrative Services) and Comcare Australia. The purpose of this information booklet is to provide workplace Health and Safety Representatives (HSRs) in Australian Public Service (APS) employment with an increased understanding and awareness of air-conditioning, indoor air quality and thermal comfort. This booklet does not purport to provide instant answers to workplace problems which may be associated with office air conditioning. It does, however, attempt to raise awareness, provide steps to follow and issues to consider when discussing air-conditioning issues in the workplace. It is envisaged that HSR's, the designated work groups they represent, union representatives, employers and supervisors will, in a co-operative spirit, consider and apply this material where possible to resolve problems that might arise in relation to air-conditioning. BackgroundThe development of this booklet derives from a decision of the Australian Industrial Relations Commission (AIRC) in December 1993 (Print No. L0246) following arbitration proceedings. The AIRC's consideration of air-conditioning, indoor air quality and thermal comfort issues followed from a log of claims served by the CPSU on a number of Commonwealth Departments seeking, among other things, for an award to be made which prescribed desirable temperature and humidity ranges. Commissioner Smith stated in his decision: 'I am satisfied that considerable impetus can be given to the monitoring of, and/or improving on, issues going to thermal comfort and air quality if designated health and safety representatives are firstly provided with an initial briefing on these issues; secondly, have a right to be advised of the maintenance routine and any problems associated with air-conditioning systems; and thirdly, can, within a reasonable time, have indoor temperatures checked.....In deciding in this way I am not suggesting that health and safety representatives should be trained to be experts in the field but they should have sufficient knowledge to be in position to be able to consider their responsibilities under the Health and Safety Act'. Accordingly an award clause has been inserted into a number of CPSU Commonwealth employment awards which provides for an information package to be developed by the parties and provided to HSRs. It also provides that HSRs have access to information concerning workplace air-conditioning systems (appendix 1). The relevant Award should be read in conjunction with the Occupational Health and Safety (Commonwealth Employment) Act 1991 (referred hereafter as the Act), where the respective duties of employers and HSRs are defined. Nothing provided by the award clause alters the operation of the Act. The award clause adopted by the AIRC is framed in such a way as to provide HSRs with access to information and the ability to seek that action be taken to address problems that may be peculiar to their designated work group. It should be noted that it is the employer's responsibility to act in accordance with the award and therefore respond to requests from HSRs. It is expected that in addressing issues or problems relating to air-conditioning the parties will do so co-operatively and sensibly. The award clause does not give the HSR or any individual the right to take unilateral action without consultation and co-operation. The clause is framed in such a way as to firstly provide for greater awareness of workplace air-conditioning and secondly for the provision of information relating to air-conditioning and thermal comfort issues. By providing this booklet it is intended to facilitate HSRs, union representatives and employers and supervisors working co-operatively to address air-conditioning issues. Whilst this guide applies to specific Awards, the information is also made available to other HSRs and employers to assist with the management of OH&S issues relating to air-conditioning. PART 2 - Procedures for Resolving Health and Safety Issues at the WorkplaceGuideline for Resolving Air-conditioning Issues in the WorkplaceIntroductionThis section looks at ways in which air-conditioning issues can be addressed in the workplace, including situations where the premises are not owned by the Commonwealth. Where references are made to the powers of the HSR, these are consistent with the powers contained in the Occupational Health and Safety (Commonwealth Employment) Act 1991 Act and detailed in the Comcare HSR Handbook. The HSR and air-conditioningAs well as performing their normal role of representing their designated work group (DWG), the HSR plays an important role in helping the employer to identify the nature of potential hazards affecting employees, and the potential effects of exposure to these hazards. The HSR can access any information under the employer's control about the OH&S aspects of the operation and maintenance of air-conditioning systems regulating the air quality of Commonwealth workplaces. Where the Commonwealth owns the premises, this should pose few problems. Where the Commonwealth is a tenant in rented or leased accommodation, however, and the owner is not a Commonwealth employer and therefore not covered by the Commonwealth's OH&S Act, there is no obligation on the owner under the Act to provide information either to the employer or to the HSR. Information on air-conditioningThe HSR does not need to be an expert on air-conditioning systems to deal with air quality issues, as there are a number of ways in which they can inform themselves sufficiently to enable them to exercise the powers provided by section 28 of the Act. Australian Construction Service has developed material on air quality, thermal comfort, air-conditioning equipment and testing procedures. This is contained in Part 3 Section 2 - Technical matters and Part 4 of this booklet. Information on air-conditioning monitoring devices and the codes of practice governing air-conditioning, Australian Standard AS 1668.2 and Australian Standard AS 3666, or any related matters may be obtained from the employer's health and safety contact point, the local office of Comcare, Standards Australia and Worksafe Australia, the relevant State OH&S Authority or possibly, the local office of the involved union. The HSR may also consider:
Identifying air quality hazardsAs with any other health and safety situations, the HSR can use a number of methods to identify actual or potential hazards posed by air-conditioning systems at their workplace. These include:
Steps in resolving air quality issuesA. In Commonwealth-owned premises If the building is owned by the Commonwealth the HSR can bring the problem to the attention of the supervisor and the employer through the channels provided in the organisation's Health and Safety Agreement. If the problem has been raised before, the HSR should establish what steps are in place to address it by talking to the supervisor, the employer's OH&S Manager and/or employer's Property Manager, or the health and safety committee. In this case, the HSR should be careful to clarify the actions and time frames which have been agreed, and report the results of the investigations to their DWG. If this is the first time the problem has been identified, the HSR should consult with the supervisor of the workplace and, if appropriate, the employer's OH&S Manager and/or employer's Property Manager and attempt to reach agreement in resolving the issue. This may involve the employer agreeing to engage a consultant to assess the situation, or committing to some other form of action. In this case, it may be appropriate to implement agreed short term solutions while the consultant's investigation is taking place, ensuring that the results are made available and any agreed resulting actions occur. Often, because of the scale and complexity of air-conditioning systems, the problem may not be capable of solution at the local level and may need to be brought to the attention of the employer through the channels provided in the organisation's Health and Safety Agreement. Usually, these will involve the health and safety committee. In any of the above instances, the HSR should be careful to monitor progress on any agreed actions on a regular basis, and provide an update to their DWG and the involved union. If the HSR does not reach agreement after due consultation with their employer, and if the HSR believes a contravention of the Act or the Regulations is occurring, the HSR may issue a Provisional Improvement Notice (PIN) to their employer. The HSR should consider notifying the involved union when agreement has not been reached with the employer. The employer can then either make further efforts to resolve the issue or ask Comcare to investigate. This process is fully described in the Health and Safety Representatives' Handbook and section 29 of the OH&S (CE) Act. B. In premises occupied but not owned by the Commonwealth Problems may arise when trying to resolve air-conditioning and indoor air quality issues in Commonwealth workplaces where the employer does not own or control the air-conditioning system. This situation can occur where the premises are leased from a building owner who may not be a Commonwealth employer, and therefore not covered by the provisions of the OH&S(CE) Act. As already indicated, the HSR has no absolute right to information on air-conditioning matters held by the owner of a building leased by the Commonwealth and unless the lease agreement between the Commonwealth employer and the building owner addresses the matter of air-conditioning appropriately, the employer may not be able to respond immediately to concerns raised in the workplace. In this case, once the HSR has brought an air-conditioning issue to the attention of their employer through the channels provided in the Act and the employer's Health and Safety Agreement, and has been advised that the building is not owned by their employer, they should try to reach agreement with the employer on a strategy for the employer to take the matter up with the building owner. This strategy should include desired outcomes and time frames. The HSR and the employer should agree on a strategy for regular feedback on the progress of negotiations with the building owner. If the building owner does not wish to co-operate, the HSR may ask the employer to approach the local Comcare office to determine what action, if any, could be taken through the appropriate State Government OH&S Authority to have the problem resolved. In any case, the HSR should report back to their DWG on any agreements reached, monitoring procedures agreed, and as appropriate, any progress against these agreements. If the HSR does not reach agreement after due consultation with their employer, and if the HSR believes there is a contravention of the Act or the Regulations, they can issue a PIN to their employer. A copy of the PIN should also be provided to the building owner in accordance with the requirements of the Act and a copy provided to the involved union. The employer can then either make further efforts to resolve the issue or ask Comcare to investigate. This process is fully described in the Health and Safety Representatives' handbook and section 29 of the OH&S Act. Lease Agreements The best way to address air-conditioning issues in leased premises is to incorporate them into new lease arrangements or building plans before construction. New lease agreement should include a HSR's right of access to air-conditioning records and operational manual. Various Agencies and the business units of Departments have developed documents describing the standards they require of a building that they lease, purchase or occupy. There is no central technical standards setting organisation that has the role of determining general (non-OH&S) requirements for air-conditioning systems serving buildings occupied by APS employees. When entering into lease arrangements (or other commercial arrangements) APS employers are required to develop documentation consistent with OH&S guidelines. In developing lease agreements employers may consider the appropriateness of adopting lease guidelines produced by Australian Property Group (APG) and/or Australian Estate Management and other Agencies that have recently developed lease agreements. Such guidelines will generally have been produced when new buildings have been commissioned. Many current leases were entered into before the Commonwealth's Occupational Health and Safety legislation became effective and may have a number of years to run. In these cases, landlords and lessors may be prepared to co-operate with APS employers to provide information, that the employer is obliged to pass onto the HSR. Landlords and lessors do not have to provide information to employers, under the Commonwealth's OH&S legislation. In any case, before moving into new premises or modifying existing air-conditioning systems, APS employers would be well advised to take every reasonably practicable step to ensure that the premises or the proposed changes are consistent with their responsibilities under the OH&S (CE) Act. The HSR has the right to be kept informed and to be consulted by the employer during the planning stages of workplace change. Most Health and Safety Agreements allow for this consultation to be conducted through the organisations health and safety committee. Emergency SituationsWhere the indoor air quality poses an immediate threat to health and safety of employees, the emergency procedures detailed in section 37 of the OH&S (CE) Act should be invoked. PART 3 - Answers to Common Questions About Air-conditioning
|
| Q | What can management do when the temperature lies outside the comfort range of 20° to 26°C? |
| A |
When the temperature at the workplace becomes uncomfortable, this will have a direct effect on productivity and staff morale. Under conditions where light work and similar sedentary tasks are carried out (in the absence of appreciable heat radiation such as from hot uninsulated roofs), the indoor dry-bulb temperature should be in the range 18° to 30°C. This can be measured simply by an ordinary thermometer. It is important that management respond to complaints about temperature fluctuations. Management should investigate the complaints and monitor trends in the movement, ie. is the temperature continuing to move outside the comfort range. Management could respond to temperature problems in any of the following ways:
Where the workplace is unacceptably uncomfortable then consideration should be given to moving affected staff to suitable alternative accommodation. If this is not possible, then paid leave can be provided to staff until the temperature returns to a satisfactory level. |
| Q | In a leased building, what action can be taken to improve air-conditioning? |
| A |
Principally the lease is the only power that an employer has over the building owner in this regard. If the air quality is a risk to health, then processes exist under the OH&S (CE) Act for Commonwealth employers and employees to address this. Action could be taken by an employer directly or through the Building Management Committee (or similar body) if one exists, to exert pressure on the lessor through lease arrangements. Also lobbying other lease holders may be appropriate to see if change can be effected. The HSR can issue a PIN to their employer and can give a copy to the Building Management Committee, and is required under the OH&S (CE) Act to give a copy to the building owner. If the matter cannot be resolved at the workplace and a dispute exists, Comcare can be requested to conduct an investigation. Alternatively the employer, employee or union may wish to raise the matter with the local OH&S Authority where a building owner is in breach of local OH&S legislation. This can be done by raising the matter with any Comcare office. |
| Q | What is to be done if a building owner refuses to give information to health and safety representatives? |
| A |
The building owner is not bound under the OH&S (CE) Act to provide the HSR with information. The HSR's powers under the Act concern their relationship with their employer. An employer may be able to get the owner to provide the information which the employer can then pass onto the HSR. |
| Q | What does an employer do if staff believe the air-conditioning is causing problems (noise, hot, cold, stuffiness, asthma, colds etc.)? |
| A | An employers duty of care requires them to take all reasonable practicable steps to resolve any workplace health problems. The employer should take steps to investigate that a problem exists. This typically would involve consulting staff and the HSR and referring any problems identified to building management. In some cases a consultant may be commissioned to provide specialist advice in identifying problems and methods of resolution. |
| Q | What does an employee do if she/he believes the air-conditioning is causing problems (noise, hot, cold, stuffiness, asthma, colds etc.)? |
| A | The most important thing is to tell somebody who may be able to do something about it. This will normally be the supervisor or HSR. If the employee feels that the working environment is the basis of a medical problem a workers compensation claim may be submitted. |
| Q | What do you do when you are sharing a building and smoking is allowed elsewhere in the building? |
| A | NOHSC has issued guidelines aimed at achieving a smoke free workplace. It is the policy of the Commonwealth as an employer that smoking in the workplace is not acceptable at any time. In a shared lease building it is an issue to be taken up by the employer with the lessor. |
| Q | What is the Role of the Building Manager? |
| A | Usually the Building Manager is the person in the Agency who is responsible for building maintenance issues. Their role will be determined by the employer. |
| Q | What is the Role of a Property Manager? |
| A | The property manager is the agent of the owner and usually acts for the owner in matters relating to the operation and maintenance of the leased premises. They will be governed by the lease provisions. |
| Q | What is a Building Management Committee? |
| A | In some buildings, typically where there are several tenants, there will be a building management committee. The building management committee is normally responsible for negotiating on behalf of all tenants with the property manager or owner on matters related to common use of the building. |
| Q | What does a Building Management Committee do when there is an air-conditioning Problem ? |
| A |
The building management committee should negotiate with the building owner to have the matter rectified - if this proves unworkable the Committee could approach the State or Territory OH&S Authority regarding the building owner's duty of care to third parties - Again there must be a risk to the health of persons, not just an issue affecting persons comfort. The lease document is the strongest weapon that an employer has against an uncooperative building owner. Comfort of employees, ie. questions of indoor air temperature and humidity, must be addressed in a lease agreement if the employer is going to have the power to take steps against a building owner where these standards are not maintained. |
Section 2 - Technical Matters
| Q | What is the correct temperature in a workplace? Are there upper and lower limits ? |
| A |
Office temperature limits are usually set on comfort criteria and there is currently no general Commonwealth employment entitlement to particular levels of thermal comfort. For general office work, people often find 20° to 24°C to be a comfortable temperature in winter when they are wearing winter clothes; they usually find 23° to 26°C to be a generally comfortable temperature in summer when they are wearing summer clothes. Temperatures a few degrees outside the comfort ranges, while uncomfortable, are unlikely to affect health if people dress suitably. However it is commonly accepted that office workers are increasingly unproductive as conditions become uncomfortable, so the Commonwealth strives to provide comfortable conditions. |
| Q | How long are employees required to stay in an enclosed building when the air-conditioning is off? |
| A |
In order to minimise objectionable odours (such as body odour) air-conditioning systems usually deliver far more fresh air than is necessary for health reasons; thus 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. In respect of air-temperature, in a still air office environment, there should be no adverse health effects, for normally healthy people, from working when the dry bulb air temperature is within the range 18° to 30°C. 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°C people will become uncomfortable and productivity is likely to drop. Some work situations involve the use of substances which are potentially hazardous; in these situations (and unless an alternative course of action has been planned) it would be wise to evacuate all potentially affected work areas when the air-conditioning and ventilation systems are not operating properly. |
| Q | Should staff work in low temperatures where these temperatures are maintained for equipment (e.g. computer) reasons? |
| A |
There are situations where there is a real need to work in hot or cold conditions, or to move regularly from warm to cool places - some factory situations and frozen food handling situations are typical cases. In these cases, where people are wearing suitable clothing, there should be no temperature related health hazard. In offices workplaces it is rare for there to be computer etc. related reasons for the air temperature to be uncomfortably hot or cold. Where this happens it would be wise for the situation to be reassessed by an air-conditioning system designer. |
| Q | What is humidity? |
| A | Humidity is the amount of moisture in the air. Absolute Humidity is the most important factor regarding the effects of humidity on people, whereas Relative Humidity is important for static electricity control and the condition of furniture and paper. |
| Q | What impact does humidity have in the workplace? |
| A |
Extremes of humidity occur naturally around the world from very low in cold and desert climates to high in the tropics. Outdoor relative humidity can vary from below 10% to a high of 100%. Very low levels of relative humidity are common in high flying aircraft. There is no supported scientific evidence to show that extremes of humidity have a significant impact on the health of normally healthy people. However extremes can lead to discomfort if surrounding environmental circumstances are not adapted to allow for them. The indoor absolute humidity to a large extent tracks the prevailing outdoor absolute humidity. In cool dry winter weather heating the air lowers the relative humidity (without altering the absolute humidity), in winter low relative humidity in cool climates is essentially inescapable. In warm humid summer weather air-conditioning operates to reduce absolute humidity. Air-conditioned buildings are more comfortable than outdoors and premises without air-conditioning, because they are cooler and less humid. In summer, if the air-conditioning breaks down and the work place is warm and humid there is usually a negligible threat to health in healthy people engaged in sedentary activities. The main concern is discomfort. The discomfort can generally be alleviated by increasing ventilation or increasing air movement with fans and adjusting clothing to help sweat evaporate. In these circumstances, while conditions may not be ideal, they may not be worse than will be experienced on leaving the work place. In buildings with properly operating air-conditioning, low relative humidity (and low absolute humidity) is the most likely humidity extreme to occur. This condition is usually a reflection of the prevailing low absolute humidity outside and therefore cannot be taken as a deficiency peculiar to the workplace. |
| Q | How much air should be delivered to a workplace? |
| A |
The Australian Standard AS 1668 part 2 (2002) specifies the minimum amount of outdoor (i.e. fresh) air that should be supplied, for offices in litres per second per person depending on allowances related to the air filtration arrangements in place. Buildings designed and constructed to comply with earlier editions of AS 1668 Part 2 need only meet a 3.5 litres per second per person requirement. A much larger amount of air must be delivered to an office to warm or cool it so the fresh air delivered to an office is, in some cases, only about 10% to 20% of the total flow of air. Some air-conditioning systems deliver a constant flow of air into each room (and this amount of air is different for different buildings) but others vary the flow in order to control the room temperature. Measuring the amount of air delivered into a room gives a guide to how well the system is operating if the measured amount is compared to the amount of air that the system designers intended. There is no general rule of thumb about how much air should be delivered to a room. |
| Q | Who can provide independent professional advice on the quality of air-conditioning? What are the names of some air-conditioning consultants? Who should "check" air-conditioning? Who can test for air quality? |
| A |
This guide cannot offer specific advice about the choice of consultants or who can test for air quality except to point out that:
|
| Q | What regulations and codes apply to air-conditioning? |
| A |
The Comcare approved codes of practice that relate to air-conditioning incorporate the following documents;
|
| Q | What are Legionnaires' Disease, Pontiac Fever, Hypersensitivity Pneumonitis? |
| A |
Legionnaires' Disease is a potentially fatal illness characterised by pneumonia, caused by infection with legionella bacteria. The incubation period of the disease is from 2 to 10 days, and the attack rate is low. Symptoms include an abrupt onset of high fever, non-productive cough, chills, headache, and muscle pain. Pontiac Fever is a self limiting, short-duration, non-fatal fever caused by legionella bacteria. The incubation period of the disease is from 5 to 66 hours and the attack rate is up to 95%. Symptoms include chills, headache, muscle pains and other flu-like symptoms. Hypersensitivity Pneumonitis is a respiratory illness caused by inhalation of the spores of various types of micro-organisms. It is also known as Extrinsic Allergic Alveolitis. |
| Q | What is a thermostat and how does it function? |
| A |
A thermostat is the main instrument that controls the temperature in an air-conditioned space. Usually a thermostat is an instrument contained in a small plastic or metal box located on the wall of a room, about 1.5 metres above the floor. Sometimes the thermostat is located out of sight behind an air grille or within the air-conditioner. Heat generating equipment such as computers and photocopiers, can affect the operation of the air-conditioner if placed near a thermostat. |
| Q | What is an air-conditioning unit 'service'? |
| A |
An air-conditioner is a machine which is like a motor car in that most service items are concerned with keeping it running - items such as greasing bearings, changing oil, checking refrigerant gas levels, checking and adjusting gauges and machine parts etc. A few service items relate more directly to the conditions experienced by the building occupants - these items primarily relate to cleaning or replacement of air filters, inspection and cleaning of cooling coils and other places where water may often be found, checking for obstruction to air flow and, checking and adjusting of controls. |
PART 4 - Detailed Information About Air-conditioning
Air-conditioning - What is it?
A building's air-conditioning has, with considerable justification, been described as "The lungs of the building. The air-conditioning system draws in outside air, filters it, heats, cools or humidifies it, circulates it around the building, then expels a portion of it to the outside environment."
By definition, air-conditioning is the control, within a space, of the different properties of the air within that space. These properties include temperature, humidity, air speed and the cleanliness of the air (amount of dust, odour, & other contaminants).
Air conditioning systems assist building occupants in three main ways:
- they help to maintain their thermal comfort;
- they provide fresh air for the building occupants ie. they operate as ventilation systems;
- they remove contaminants from the air, in particular, body odour.
Thermal Comfort and Ventilation
Thermal Comfort - The basics
Each person is the expert on their own thermal comfort. In an ideal world each person would have their own air-conditioning system. As this is not practicable, air-conditioning systems are designed to provide conditions that have been determined as providing acceptable working conditions for most members of a workgroup.
While thermal comfort is to a large extent determined by temperature, air movement and relative humidity it is affected by many factors. In scientific terms thermal comfort is complex.
A person's perception of thermal comfort is affected by air temperature, air speed, floor temperature, vertical air temperature gradient, humidity, clothing, activity level (the amount of physical exertion), radiant temperature asymmetry, and mean radiant temperature (the average temperature of the walls, floors etc. that surround them). Sun penetration into a building is, of course, quite important.
Not all aspects of thermal comfort can be controlled by an air-conditioning system. Some aspects are strongly influenced by the way a building is sited, its window treatments (choice of glass, curtains, blinds etc.) and its other architectural features.
In most circumstances, however, the three most important factors are air temperature, mean radiant temperature and air speed.
Thermal Comfort - The effect of air temperature
Air temperature is the most important thermal comfort factor and it is the air-conditioning system that usually determines the temperature of the workplace.
There is no scientifically correct "best" temperature. The best temperature is the temperature that most people find comfortable, without particularly discomforting the few people who have unusual temperature preferences. The best temperature depends on the personal preferences of people, the clothing they wear, the work they are doing and environmental factors such as humidity.
In common office environments people will be comfortable when the temperature is in the vicinity of 23°C and it is common for air-conditioning systems to be arranged to maintain temperatures in the range 20°C to 26°C.
For general office work, people often find 20° to 24°C to be a comfortable temperature in winter when they are wearing winter clothes, and they usually find 23° to 26°C to be a generally comfortable temperature in summer when they are wearing summer clothes.
Extremes of air temperature may have an adverse influence on health in air-conditioned spaces however this would only happen in the event of gross malfunction of the air-conditioning system.
Temperatures may be measured accurately and conveniently with traditional glass thermometers or with affordable electronic measuring devices.
Thermal Comfort - The effect of mean radiant temperature
Broadly speaking, mean radiant temperature is the average temperature of the surfaces of the windows, curtains, ceilings, walls, floors etc. that surround a person; however the sunlight coming through windows also contributes to the mean radiant temperature in a workplace.
Mean radiant temperature is as important as air temperature in its effect on thermal comfort.
The mean radiant temperature of a space is largely determined by the architecture, construction and orientation of the building, and the type of window treatments (curtains, blinds etc.) that are fitted.
The internal areas of a building will largely be unaffected by windows, badly insulated walls etc. Thus the mean radiant temperature will be predictable. Conversely, the areas near windows will have varying radiant temperature conditions and the influence on comfort will be more significant.
The mean radiant temperature of a space may often be improved by simple measures such as the fitting of curtains or blinds to windows.
Thermal Comfort - The effect of air speed
Common experience shows that air speed (ie. the speed of movement of the air that surrounds us) affects our comfort.
A "still air" thermal environment (which is seldom really still, it is just that we do not notice very low air speeds) is often acceptable; for example, when we are sitting quietly at home on a nice calm day.
If the air speed is very high we will be uncomfortable, more or less regardless of how we have adjusted the temperature.
In the achievement of thermal comfort there is a trade off between air speed and temperature. In an air-conditioned office the temperature may be slightly higher than normal if the air speed is similarly high.
If the air temperature is too high it cannot be compensated for by adjustment of air speed (or vice versa).
There is also the separate sensation of draught.
While there is no particular air speed for satisfactory thermal comfort it is necessary for the air speed to suit the temperature. It is also necessary for the conditions not to be draughty and for there to be sufficient air movement to prevent the formation of local "hot spots" or localised areas of increased odour level.
Air speed is commonly measured with an Anemometer. There are many different types of anemometers and each one suits a particular circumstance.
Usually, air-conditioning systems are designed to produce maximum air speeds of 0.25 metres per second, in occupied areas.
Air speed is usually determined by the need to ensure that there is a sufficient interchange of air in the building, to remove odours, control temperature and otherwise provide a pleasant working environment.
Thermal Comfort - The effect of humidity
For people performing very light or sedentary activities the effect of humidity on comfort is not great.
Many people know that humidity is important to comfort in their daily private lives but they may not appreciate that the situation is different in an air-conditioned space where the temperature is controlled.
People are quite insensitive to humidity levels over a wide humidity range - at the temperatures which are normally found in air-conditioned places. Also, the effect on comfort of a shift in humidity may be compensated for by a small adjustment of air temperature.
Higher humidity, for example, makes a person feel warmer thus a slight lowering of temperature will compensate for the comfort effect of this higher humidity.
The situation is different when the air temperature is high (approaching 30 Degrees. C.) or physical activity is great; or just after a person has experienced these conditions - such as when they walk into an air-conditioned building in Darwin, in summer, after being outside for an hour or so.
On these occasions the influence of humidity is much more important to comfort.
The effect of humidity on office workers
Standards for thermal comfort for indoor sedentary workers recommend an operative temperature of 20° to 26°C depending on the season.
Humidity has little effect on comfort if people are not sweating, a wide range of relative humidity is therefore acceptable. At the recommended indoor air temperatures there are unlikely to be additional health risks for normal healthy people from relative humidity levels expected to be found in Australia.
Low humidity
Generally, normally healthy humans tolerate low humidity without ill effects. There are no known serious health disorders that are directly related to exposure to low humidity. A few people may experience discomfort from dry eyes, nose and throat but this resolves immediately with return to higher humidity. The office environment cannot usually be held solely responsible for these problems because the outside humidity is usually also low.
People are in fact much more sensitive to extremes of temperature than to extremes of humidity.
High humidity
There are no known direct health effects of high humidity.
People living in the tropics are exposed to high humidity for much of the year.
Humidity in the air-conditioned environment is usually controlled to less than about 60%. Many people doing sedentary work and wearing light clothing at appropriate air temperature will be comfortable at higher relative humidity.
Indirect effects of high humidity may occur if relative humidity exceeds about 75% for extended periods of time (days).
Adverse effects are more likely in conditions of poor ventilation and low air movement.
Conclusions
There is no evidence that serious ill-effects will occur as the result of occasional excursions of relative humidity outside the levels usually recommended for indoor thermal comfort.
Adverse health effects related to humidity are unlikely to arise in properly air-conditioned work places. There may be as many potential health problems associated with artificially controlling humidity, especially with humidification, as there are to extremes of humidity.
When considering humidity in air-conditioned workplaces, it should be remembered that people will be exposed to greater extremes of humidity when outside and in homes without air-conditioning, than in the workplace.
In cases of breakdown of air-conditioning, situations should be dealt with according to the local circumstances. Limited periods of extremes of relative humidity need not be a matter for concern and would rarely be a primary reason for leaving the workplace.
Extremely low relative humidity in air-conditioned buildings will be the direct result of low prevailing outdoor humidity. In these circumstances higher humidity is unlikely to be found elsewhere, so that there is unlikely to be any advantage to leaving the workplace.
Likewise extremely high humidity will be the direct result of high prevailing outdoor humidity.
The main concern is discomfort.
The discomfort can generally be alleviated by increasing ventilation or increasing air movement with fans and adjusting clothing to help sweat evaporate. In these circumstances, while conditions may not be ideal, they may be no worse than will be experienced on leaving the work place.
Ventilation
Buildings may be naturally ventilated by airflow through windows, permanently open grilles etc. Alternatively they may be mechanically ventilated by fans which either draw air into the building or exhaust air from the building to the outside (thus causing air to come in through various openings).
Office buildings today are usually mechanically ventilated (fresh air is provided by fans, ducting etc.) and this mechanical ventilation is normally achieved by the addition of fresh air to the large amount of air that circulates between the occupied spaces and the main air-conditioning units.
Mechanical ventilation is more reliable than natural ventilation as a means of moving fresh air to all parts of the building. With mechanical ventilation it is easy to provide filters to remove dust and pollens from the fresh air.
Ventilation rates
When a new building is required to be mechanically ventilated it must be ventilated in accordance with Australian Standard AS 1668 Part 2 which specifies the minimum amount of fresh air (more accurately referred to as Outdoor Air or Outside Air) that must be supplied to various parts of a building.
Older buildings may be required by building regulations to comply with earlier versions of Australian Standard AS 1668 Part 2.
This joint Australian / New Zealand Standard applies (through being called up by the building code) in all Australian States and Territories and in New Zealand.
The amount of ventilation air specified in the Australian Standard is set so as to prevent the presence of unacceptable levels of pollution in the ventilated spaces.
The Australian Standard ventilation rates are, for the most part, determined by the requirement for control of odour thus they usually ensure that occupied spaces are ventilated well in excess of requirements for health related matters.
The Australian Standard for buildings designed and constructed after 1990 requires up to 10 litres per second of fresh air to be supplied for each occupant of an office with the exact figure depending on details of design of the air-conditioning system.
In practical terms the delivery of fresh air to a space is assessed by measurement of fresh air intake into the building and calculation of the distribution of this fresh air within the building. For all but simple situations this is a complex matter with the assessment being undertaken by an appropriately qualified engineer.
The Air Conditioning System
Air-conditioning designs vary greatly and each building has its own design. It is thus difficult to make statements about the design and operation of "typical" air-conditioning systems.
Nevertheless, all air-conditioning systems have some things in common and a good understanding can be obtained by examining a simple but, to some extent typical, modern system. This diagram illustrates a typical arrangement of an air-conditioning system.
Overview
The air provided to the workplace in an air-conditioned office enters the rooms through either an outlet located in the ceiling (called a diffuser) or an outlet located in a wall (called a register). This air is called the supply air.
To control the temperature of the air in the room the temperature of the air entering the room or its volume or both are adjusted to ensure that on mixing with the other air in the room the temperature is maintained at a comfortable level. The temperature is controlled by a thermostat in the work area. The thermostat will, under normal circumstances, be able to maintain the air temperature close to the desired temperature (within a couple of degrees).
For the thermostat to work correctly it is important that heat producing sources, such as computers or incandescent reading lamps, are not placed close to it.
In summer the conditioned air entering the room will usually be considerably colder than the required room temperature, perhaps as low as 10°C, whereas in winter it may be warmer than the desired temperature. This ensures that on mixing with the air in the room, a comfortable temperature can be maintained.
Air (the return air) leaves the room usually through openings in the ceiling (often adjacent to light fittings), or through door openings, door grilles, corridors or grills in the wall. This air then passes into a return air duct.
Return air travels along the return air duct, a proportion is exhausted to the outside of the building, and the remainder returns to the air-conditioner for mixing with fresh air and for recirculation within the building.
The fresh air inlet is located so that air from the return air exhaust, cooling tower and boiler exhausts are not drawn into the system in quantities that would adversely affect the health of the occupants of the building.
Australian Standard AS 1668 part 2 specifies the minimum amount of fresh air that should be taken into a building for mixing with the recycled air.
These amounts are determined during the design of the air-conditioning plant, and when significant alterations to the building are undertaken. On leaving the air-conditioner the supply air passes into the supply air duct(s) until it reaches the diffusers or registers which distribute it into the air-conditioned room(s).
In some systems additional heating devices and/or air flow control units (variable volume units) may be provided in the ducts close to the outlets to provide more precise control over the air temperature in the room.
An air-conditioning system may take some time (often some hours) to stabilise the temperature in a building if it has been turned off for some time. If a fault develops it is therefore important that it be reported quickly to ensure corrective action can be taken, with the least discomfort to occupants.
Ducting
Air is supplied to and returned from the workplace through ducts. These are the large pipes in the ceiling space in most buildings.
Air conditioning ducts are usually made from sheet metal and covered in an insulating layer. The insulation is provided in order to minimise heat loss or gain into or out of the ducts, to reduce the cost of running the system and to reduce noise.
Most duct insulation has a vapour barrier around it, this is a moisture proof layer of material that prevents humid air from reaching a cold surface of the duct. This prevents humid air from condensing on the cold surfaces of the duct which could lead to corrosion of the duct surfaces and premature failure of the system or damage to the building.
The air-conditioner
The size of air-conditioners vary in accordance with the volume of the workspace. In a small building small integrated wall mounted units may be adequate, whereas in a large building the air-conditioner may be located in a plant room and could be as large as 5 metres wide by 10 to 15 metres long and 5 to 10 metres high, assembled from individually designed components.
All air-conditioners, whatever their size, will usually comprise a housing containing a filter, fan, cooling coil and heating coil, with in some installations a humidifier.
Filter
On entering the air-conditioner the air first passes through a filter to remove particulate matter (such as dust and pollens) from the air.
Office air-conditioning system filters will not normally remove gases or odours from the air. Odour and gasses are controlled by the addition of a fresh supply air that is re-circulated through the building. This dilutes the odours to an acceptable level.
In most cases, air filters are fibrous material bags or panels. When the air passes through the filter material dust particles are attracted to (and stick to) the individual fabric fibres.
Another filtration method which includes the use of electrostatic filters which use high voltage electrodes to electrically charge the dust particles, with the dust particles then attracted to electrically charged plates.
After a fabric filter has been in use for some time the filter gradually becomes choked with dust. At this stage the filter is usually removing a higher proportion of particles from the air but is possibly allowing less air to pass through it and consequently needs cleaning or changing, depending on the type of filter.
Fan
On leaving the filter the air passes through a circulation fan. The fan provides both the force to draw the air along the return air duct from the air-conditioned room and to propel the air along the supply air duct back to the air-conditioned room.
Cooling
Air, after passing through the fan enters the cooling unit and passes through a cooling coil. The air passes over a number of metal tubes, usually with thin metal plate fins attached to the outside (somewhat similar to a car radiator). Chilled water at about 6°C runs through the inside of the tubes cooling the air as it passes over them.
If the air passing through the cooling coil is humid, some of the moisture will be taken out of the air, de-humidifying it. This moisture is collected in a condensate tray and directed to a waste outlet.
The amount of coolant flowing through the coil is controlled to adjust the temperature of the air leaving the coil and consequently the temperature of the air entering the air-conditioned room.
In a few installations the coil is sprayed with water, this improves its cooling ability and helps to humidify the air.
The chilled water supplied to the cooling coil is cooled in a water chiller and the water chiller is typically cooled by circulation of its condensing water through a cooling tower.
In small installations the cooling means could be a small refrigeration unit providing refrigerant (rather than chilled water) to the cooling coils of the air cooler. In such an installation a cooling tower may not be required.
Heating
After leaving the cooling coil the air passes through a heating coil or a low temperature electrical heater.
The operation of the heating coil is exactly the same as the cooling coil except that hot water passes through the tubes in order to heat the air.
The water flowing to the heating coils is normally heated in a gas fired boiler installed in a plant room.
The operation of the heating and cooling units are optimised for energy efficiency and effectiveness and controlled in accordance with outside and inside air temperatures to provide an optimal environment in the building.
In cool climates the chillers will normally not operate in the cooler months, and similarly in hot weather, the boilers may not operate.
Humidifier
Sometimes the air has moisture added to it, in which case the air-conditioner includes a humidifier. A humidifier is a container of water with electric heating elements in it to boil the water and create steam. The steam is then mixed with the air before it passes into the ducts for transfer to the air-conditioned rooms.
Special purpose rooms
Special purpose rooms such as toilets, kitchens and other odour producing rooms, are vented separately to ensure, as far as possible, that odours are not drawn into the building via the return air path.
Maintenance of Air-conditioning Components which may affect Air Quality
There is one air-conditioning system component which is not normally in contact with the air that the building occupants breathe but which is important to air quality. This is the cooling tower. Most other components of interest are normally in contact with the air we breathe.
If a cooling tower is poorly maintained there is a chance that the air exhausted from the cooling tower may be contaminated with Legionella (the bacteria that causes legionnaires' disease). Under certain weather conditions air exhausted from the cooling tower may be drawn into the air inlet grille.
Cleanliness
Most air-conditioning components (ducts, coils, diffusers, filters, fans, grilles etc.) are generally inside the building and are in contact with dry air thus the fundamental requirement is that they be kept reasonably clean.
Exceptional cleanliness is not required. It is commonsense to consider that air which passes through a building and comes into contact with carpeted floors, people, office equipment etc. does not need to pass through a sterile air-conditioner and travel in sterile ductwork. The ducts, coils etc. do, however, need to be dry, and to stand the test of regular inspection and good housekeeping.
Air filters in air conditioners help to keep buildings clean. They catch dust that may settle in occupied spaces or in ductwork. In the overwhelming majority of cases air filters are of the synthetic fibrous material type.
As fibrous filters collect dirt from the air that passes through them, they typically increase (not decrease) in efficiency as they get dirty ie. they extract more dust from the air. Dirty filters are rarely a health risk on their own, however, they can progressively reduce the effectiveness of the air-conditioning system or make the system more expensive to operate.
Code of Practice
Australian Standard AS 3666 is called up by Comcare as an approved code of practice. This standard prescribes a number of maintenance measures including:
- annual inspection of ductwork in the vicinity of moisture-producing equipment, and cleaning where necessary;
- annual inspection of coils, trays, sumps, condensate lines, duct terminal units, air intakes, exhaust outlets; and cleaning where necessary;
- annual inspection of air filters, where installed and cleaning or replacement where necessary;
- monthly inspection of humidifier components, and cleaning where necessary;
- monthly inspection of cooling towers, and cleaning where necessary - with six month maximum cleaning intervals unless otherwise approved.
Correct Location of Fresh Air Inlets
In designing an air-conditioning system the fresh air inlets should be located so they will allow the air-conditioning plant to have access to fresh air that is not of poorer quality than that generally found in the locality.
Correct location of air inlets is specified in Australian Standard AS 1668.2.
Australian Standard AS 1668.2, in clause 4.3.1, states
"Intakes for outdoor air shall be located and arranged so that under all conditions of normal operation -
(a) contamination from air exhausts, cooling tower discharges, work processes and other sources of pollution do not reduce the quality of outdoor air entering the intake to a level significantly below that of the outdoor air in the locality, except where outdoor air entering the intake is treated to achieve the same effect; and
(b) the effects of wind, adjacent structures and other factors do not cause the flow rate of outdoor air to be reduced below the minimum requirements of this Section."
Correct location is essential and it requires the application of careful professional judgement. Inlets, for instance, should not be located:
- downwind of a known pollutant source;
- where the exhaust fumes from delivery trucks may enter the inlet;
- where exhaust air from a building may re-enter the building via the fresh air inlet;
- where the discharge from cooling towers may enter the inlet.
Control of Moisture
Control of moisture is the most important factor in the control of microbiological growth in buildings.
The importance of moisture control is emphasised by the fact that Australian Standard AS 3666 "Air and Water Systems of Buildings - Microbial Control" almost exclusively deals with standards for moisture control and cleaning when it addresses the requirements of air handling systems in buildings.
For growth, bacteria require a moist environment. This generally occurs when the air is nearly saturated with moisture (at a local relative humidity of over 90%) or where there are moist surfaces or the like.
Yeast, moulds etc. may grow in a somewhat drier environment - as low as 60% local relative humidity for some specialised yeasts.
Control of relative humidity is not generally necessary for adequate control of microbiological growth. If it were so, human habitation of tropical & subtropical areas (Darwin, Cairns, Brisbane etc.) would not be practicable.
Some of the major considerations in the control of moisture are:
- design and location of air intakes and exhaust air outlets so that rain does not enter and, also, so that exhaust from cooling towers and similar devices does not enter;
- arrangement of cooling coils and condensate trays so that condensate easily drains away;
- careful choice and location of humidifiers so that they do not cause moisture accumulation in nearby areas (or better still, elimination of the use of humidifiers unless there is a very good reason for their use);
- particular attention to the design and maintenance of installations that used sprayed cooling coils, air washers or similar devices;
- protection of surfaces which potentially may absorb water (filters, duct insulation) from moisture, particularly by examining for correct location;
- provision of access for inspection near moisture producing equipment in ducts etc.
Indoor Air Quality
This section discusses air quality, indoor air quality standards, measurement of air quality, microbiological growth and some other issues.
For the purposes of this guide air quality is defined as the properties of breathing air related to health, irritation and odour, together with the properties of air related to eye irritation.
In extreme circumstances air quality may have an influence on skin irritation but this would be very rare in office situations.
Other properties of the air such as temperature and air speed are best described as matters of environmental comfort. They, perhaps, become a part of air quality when they reach extreme values, but this is most unlikely in an air-conditioned building.
Indoor air quality standards
Workplace Air Quality Standards are mostly set by the National Occupational Health and Safety Commission in the document titled "Exposure Standards for Atmospheric Contaminants in the Occupational Environment"; this document is known colloquially as the "Exposure Standards".
The Worksafe Exposure Standards are the successor to the Threshold Limit Values published by the Australian National Health and Medical Research Council.
Amenity Air Quality Standards
Amenity (e.g. odour) air quality standards relate to the satisfaction of people rather than to their health; thus they are measured in terms of the degree of satisfaction of a population whose interests they serve.
The customary international standard for odour control has been to aim to create an ambient atmosphere that is judged to be acceptable to 80% or more of people when they first breathe it ie. before their sense of smell becomes adapted to the odour in the atmosphere.
The odour level in buildings is controlled by local exhaust ventilation systems and the provision of fresh air to dilute the odours.
The building regulations in all Australian States and Territories (and New Zealand) require that all new mechanically ventilated buildings be ventilated (ie. provided with fresh air) in accordance with Australian Standard AS 1668 Part 2.
Australian Standard AS 1668 Part 2 mandates the supply of sufficient fresh air to control body odour (the usual major odour source in buildings where smoking is substantially controlled) so that the air is acceptable.
It is widely accepted that ventilation in accordance with Australian Standard AS 1668 Part 2 is sufficient to provide satisfactory conditions in buildings which do not have unusual or excessive sources of pollution within them.
Microbiological Contamination - Measurement and Standards
Microbiological contamination may be measured in air and it may be measured on the surfaces that come into contact with the air.
These measurement results are commonly expressed as Colony Forming Units (CFU) per Cubic Metre of air (ie. CFU/M3), CFU per square metre of surface area (CFU/M2) or CFU per gram of dust/dirt (CFU/Gram).
When results are expressed in terms of CFU, they are usually accompanied by a statement of what type of Colony Forming Units have been measured - total micro-organisms, bacteria only, fungi only, specific species of bacteria etc.
No recognised health authority in Australia or elsewhere appears to have set a standard for the acceptable amount of microbiological contamination of air-conditioning systems that serve office buildings and similar places.
The consensus view of health authorities appears to be that the setting of quantitative standards for the microbiological content of air in office buildings is not particularly useful, and that measurement of the microbiological content of air in office workplaces is rarely helpful.
The best control of infection in the workplace is achieved by cleanliness, control of moisture, and behaviour which reduces the likelihood of infection.
Various commercial organisations (particularly those marketing testing and decontamination services) and others have proposed their own guide-lines for the evaluation of microbiological test results. These guide-lines mostly lie in the 500 to 5,000 CFU/M3 range, however they appear to have little basis other than undocumented claims of experience and should not be followed unless supported by sound scientific justification and approved by the relevant Health Authority.
Measurement of Odour
Odour is best judged with the human nose or, to put it more accurately, with a collection of human noses.
As odour relates to human satisfaction there can, by definition, be no better measure than the opinion of people.
Currently there is no satisfactory practical method of measuring the general odour levels in buildings with instruments. In some circumstances where the situation is very simple (such as when an objectionable odour is caused by a single chemical) odour may be measured by an instrument.
Measurement of air quality by use of "Mixed Gas Sensors" (sometimes called Air Quality Sensors) or by the measurement of Carbon Dioxide levels has a poor scientific basis and should not be utilised.
Measurement of Chemical Contamination
Scientific testing is available that can accurately measure the concentration, in air, of almost any chemical. However, in a typical air sample thousands of different chemicals may be detected. Testing of all of these chemicals is therefore costly, time consuming and rarely feasible. It is, for example, reported that over 4,000 separate chemical constituents of tobacco smoke have been measured.
If the chemical contaminants in indoor air are to be measured, care has to be exercised in deciding on the chemicals that are to be measured and in determining the relevance of any tests that are undertaken. It is necessary for knowledgeable experts to be consulted.
Evaluation of Proposals for Measurement of Contaminants in Air
In evaluating a proposal for the measurement of contaminants in the indoor air it may be wise to obtain satisfactory answers to questions such as the following, before proceeding
- why is a particular contaminant being measured?
- what test result would be acceptable?, what would be unacceptable?
- who (which organisation) has set the criteria for acceptability?
- if the criteria are set by a non-Australian source, are there recognised Australian criteria?
- if the criteria are from a non-Australian source, have recognised Australian authorities expressed an opinion on the suitability of the criteria?
- if the criteria are set or recommended by a testing company or the like; on what specific basis (other than a generalised claim of suitable experience) were the criteria developed? also, what independent body has agreed that the criteria are appropriate?
If these and like issues are not addressed it is possible that a report on the air contamination in a building will contain judgements and recommendations that are based on essentially unsubstantiated opinion. These judgements potentially may either understate or overstate the seriousness of a situation.
It is advisable to be most cautious about the recommendations of commercial interests, or others, who:
- make recommendations that are different (either more liberal or more conservative) than those of recognised health authorities or standards setting authorities;
- make recommendations on issues where recognised authorities have found no need to make recommendations; for example, where the recognised authorities consider that potential hazards are well managed by the application of the Building Code, Occupational Health and Safety Codes etc.;
- make recommendations on issues where recognised authorities have not found a satisfactory basis for making a recommendation.
Specific Health Issues
Legionnaires' Disease and Pontiac Fever
Legionnaires' Disease is caused by a very common bacteria (one researcher has reported finding the bacteria in 70 % of soil samples, it has also been found 50 kilometres out to sea at the mouth of the Amazon River).
Legionnaires' Disease may be serious when caught by very old or very young people; or by people whose immunity has been compromised in some way (by drugs, other infection etc.).
Legionnaires' Disease is a potentially fatal illness characterised by pneumonia, caused by infection with Legionella bacteria. The incubation period of the disease is from 2 to 10 days, and the attack rate is low. Symptoms include an abrupt onset of high fever, non-productive cough, chills, headache, and muscle pain.
Legionella bacteria will grow in cooling towers, spa baths, some hot water systems etc. if conditions are appropriate.
For infection to occur legionella contaminated air must make its way from a cooling tower (or other source) to an occupied area. This has happened where building fresh air inlets have been badly located in relation to the cooling tower discharge. It has also happened when contaminated air from a badly infected cooling tower on a nearby building has made its way to a fresh air inlet.
Control of legionella is relatively simple. The temperature of hot water must be kept high enough to kill the bacteria (normal water heaters achieve this) and other water containing places, such as cooling towers, must be periodically cleaned and decontaminated.
Pontiac Fever is a self limiting, short-duration, non-fatal fever caused by Legionella bacteria. The incubation period of the disease is from 5 to 66 hours and the attack rate is up to 95%. Symptoms include chills, headache, muscle pains and other flu-like symptoms.
Australian Standard AS 3666 1989 "Air-handling and water systems of buildings - Microbial control" is a Comcare approved Code of Practice which deals with the control of Legionnaires disease hazards.
Sick Building Syndrome & Building Related Illness
Sick Building Syndrome (SBS) is a name that has been given to a situation where a substantial number of people in a building have reported a variety of different symptoms, such as sore eyes, headache, general malaise etc.
Many sick building situations have been investigated (but few in Australia), generally with an inconclusive outcome.
Many causes of sick building syndrome have been suggested - chemical contamination, fungal toxins, low level bacterial infection, poor lighting, hysteria, general work dissatisfaction etc. but little conclusive evidence is available to date.
The term Building Related Illness (BRI) is often used to describe situations where a definite building related cause of illness has been identified. Two examples are
- Legionnaires' Disease or Pontiac Fever caused by legionella bacteria from the cooling tower on a building;
- Hypersensitivity Pneumonitis (also called Allergic Extrinsic Alveolitis) caused by fungal growth on a cooling coil or in an air washer.
Hypersensitivity Pneumonitis is a respiratory illness caused by inhalation of the spores of various types of micro-organisms. It is also known as Extrinsic Allergic Alveolitis. As Hypersensitivity Pneumonitis is caused by micro-organisms it is prevented by attention to cleanliness and the control of moisture in buildings and their air-conditioning systems - thus avoiding the growth of moulds, fungi and the like on walls etc. and within air-handling equipment.
Contamination
Occasionally there is potential for problems as a result of specific contamination within buildings.
Where this is suspected, the source of contamination should be tracked down and dealt with.
Reported sources of such contamination have included inferior building materials, some chemicals used in older style office equipment and inadequately ventilated work processes.
PART 5 - Award Clause
ADMINISTRATIVE AND CLERICAL OFFICERS' (CONDITIONS OF SERVICE)
AWARD 1986 [Print G3597 [A0323]]
18 - PROCEDURES FOR AIR-CONDITIONED WORKPLACES
| (a) | For the purposes of this award a health and safety representative is a person selected under section 25 of the Occupational Health and Safety (Commonwealth Employment) Act 1991 (hereafter known as "the Act"). |
| (b)(i) | This clause shall be read in conjunction with the above mentioned Act and Workplace Health and Safety Agreements and policies negotiated between the parties in accordance with the Act. |
| (ii) | The roles and powers of the health and safety representatives and the employer's general duty of care as provided by the Act are not to be taken to alter because of the operation of this clause. |
| (c)(i) | The parties shall by 1 December 1994 develop information for dissemination to health and safety representatives (HSRs) relating to office based air-conditioning and thermal comfort. The information will include the operation and maintenance of air-conditioning systems and levels of acceptable indoor air quality. |
| (ii) | The employer will provide by 1 April 1995 briefing sessions to health and safety representatives based on the information package developed in paragraph (c)(i) and related to the operation and maintenance records of the air-conditioning system at their workplace. |
| (d) | Upon request the employer shall provide advice to the HSR regarding the maintenance of the air-conditioning system relevant to the HSR's designated work group, including access to maintenance records and operational manuals. Where the employer is a tenant in a building not owned or controlled by the Commonwealth the employer will request the landlord for the HSR to have access to maintenance records and operational manuals. |
| (e) | Health and safety representatives shall, upon request, be provided information regarding the workplace indoor air temperature and humidity within a reasonable time. |
PART 6 - Associated Documents & Sources
Commonwealth Approved Code of Practice on Air-Conditioning which incorporates AS 3666 and AS 1668.2
Comcare Australia - Health and Safety Representatives Handbook
Occupational Health and Safety (Commonwealth Employment) Act 1991
Further information can be found in a paper titled: The employers duty of care under the OH&S(CE) Act 1991 that has been issued by the Safety Rehabilitation and Compensation Commission.
A wide variety of sources and expert advice has be considered in the publication of this guide including the PSU's Health and Comfort at Work and various papers of Professor Ole Fanger and other recognised specialists.
Publication Details
© Commonwealth of Australia 1995
This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior permission from Comcare.
ISBN — 0 642 22255 X (hard copy)
ISBN — 1 876700 22 X (on-line)