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Indoor environment, productivity and sustainable commercial buildings

Added by Your Building Administrator, last edited by Your Building Administrator on May 08, 2008 12:52

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This article provides a broad overview of relevant information about indoor environment quality (IEQ) including the importance of various aspects of IEQ, potential impact on occupants' health, well-being and productivity, and practical guidance to enhance, measure and assess indoor environment.

Authoring team for the original article:
Lead authors: Phillip Paevere and Steve Brown
Contributors: Adrian Leaman, Judith Heerwagen and Mark Luther

Contents


Summary

Indoor environment quality (IEQ) is a generic term used to describe the physical and perceptual attributes of indoor spaces. These include the thermal, acoustic and visual properties of the environment, as well as the indoor air quality.

Good IEQ in a commercial building can deliver wide-reaching real and potential benefits to occupants, employers and building owners. Benefits can be commercial in nature (e.g. reduced tenant turnover), as well as intangible or psychological (e.g. improved company image).

The IEQ in a building has the potential to impact on the health, well-being and comfort of building occupants, which in turn may impact on their productivity at work. This is a key driver in the business case for providing high quality IEQ, since salary costs make up such a large proportion of overall business costs.

One of the key challenges in assessing the link between enhanced productivity and good IEQ is being able to define and measure both 'good' IEQ and productivity in meaningful terms. This can be complex because productivity indicators are highly specific to an organisation's context and business goals, and the definition of 'good' IEQ is highly dependant on qualitative factors such as occupant satisfaction.

This article of Your Building provides a broad overview of relevant information about IEQ. It discusses the importance of various aspects of IEQ and their potential impact on occupant health, well-being and productivity, and provides information about measuring and assessing IEQ. Practical guidance for enhancing the indoor environment, and links to further reading and case studies are also given throughout the article. The reader should realise that high levels of IEQ cannot be precisely and generically defined for optimum performance of office buildings in this article or any guideline. Every building is unique, as are its occupants. Your Building is intended to assist building designers, owners and occupiers to best adapt their built environment to meet their unique needs.

Definitions

Indoor environment quality (IEQ) is a generic term used to describe the attributes of enclosed spaces, including the thermal, acoustic and visual environment, as well as the indoor air quality. Both physical (measurable) and perceptual (human comfort) factors play a key role in defining IEQ.

The key components of IEQ are:

The IEQ in a building may have an impact on the health, well-being and comfort of building occupants, which in turn may impact on their productivity at work.

Indoor air quality
Indoor air quality (IAQ) refers to the totality of attributes of indoor air that affect a person's health, well-being and comfort.

IAQ is characterised by:

  • physical factors, such as ambient temperature, humidity and ventilation rates
  • air pollutant factors, such as pollutant levels and exposure times
  • human factors, such as occupant health status, individual sensitivity and personal control.

Major contributors to poor IAQ include:

Other factors that may contribute to poor IAQ include poor cleaning practices, poor moisture control (e.g. water leaks or persistent damp surfaces), human occupancy effects (e.g. odours), poorly designed enclosed garages and poor building maintenance.

Assessment of IAQ and its impact on human health requires consideration of a number of issues, including ventilation, temperature and humidity, levels of air toxics, and the presence of respirable particles and fibres, environmental tobacco smoke, micro-organisms, carbon monoxide and nitrogen oxides.

Improved IAQ can be achieved by:

IAQ is currently (or likely to be in the future) covered by a range of air quality policies, regulations and standards.

Thermal comfort
Thermal comfort refers to 'a condition of mind which expresses satisfaction with the thermal environment' (ISO, 1994).

Thermal comfort therefore describes a person's psychological state of mind about their thermal climate and is usually described simply in terms of whether they are feeling too hot or too cold. Thermal comfort can be difficult to define parametrically because a range of environmental and human factors need to be considered in order to determine what will make people feel comfortable. These factors include:

In practice, a high level of thermal comfort is considered to occur when a high proportion (e.g. 80% or more) of building occupants are predicted to be satisfied with the thermal conditions, based on the above factors. A significant influence on thermal comfort is whether a space is mechanically conditioned or naturally conditioned — these are known to require different physical conditions for thermal comfort, since occupant expectations in the latter are shifted due to different thermal experiences and availability of individual control.

Thermal comfort cannot be measured by any one of the above parameters alone, although when these parameters are outside scientifically determined ranges, the proportion of satisfied building occupants will decrease. Therefore, the parameters are useful indicators for controlling the climate in buildings.

Thermal comfort can be specified according to a statistical prediction of the proportion of building occupants who are comfortable, based on the parameters described above. ISO Standard 7730, Moderate thermal environments — Determination of the PMV and PPD indices and specification of the conditions for thermal comfort (ISO,1994), specified three levels of acceptance for thermal comfort in mechanically conditioned offices, since, in practice, the levels attained will depend on a range of factors: technical, cost, environmental, energy and performance. Acceptance of thermal comfort was expressed as the Percent People Dissatisfied (PPD) at levels of <6%, <10% and <15%.

Acoustic environment quality
The acoustic environment quality refers to the totality of the acoustic characteristics of a building that impact on the occupants' aural perceptions.

Of all the categories of IEQ, acoustic quality is most often the cause of greatest occupant dissatisfaction (Jensen et al., 2005). Occupant perceptions of the acoustic environment quality have important implications for productivity and can be affected by:

Contributors to dissatisfaction with acoustics can be caused by interruptions, equipment noise and lack of privacy or control over noise.

Control of acoustic environment quality can be achieved in three basic ways:

  • eliminating noise sources
  • isolating noise sources
  • masking unwanted sounds.


Luminous and visual environment quality
The luminous and visual environment quality refers to the totality of the luminous and visual characteristics of a building that impact on occupants' visual perceptions.

Luminous and visual environment quality can have a significant impact on occupants' abilities to perform tasks, especially if they are visually intensive. Occupant perceptions of luminous and visual environment quality can be affected by:

Major sources of dissatisfaction with the visual environment include limited access to daylight, inappropriate light levels, glare levels and lack of control over the environment.

Strategies for #improving the luminous and visual environment are based on maximising occupant comfort. This can be achieved through appropriate task lighting and integration of daylighting and electric lighting systems for ambient lighting wherever feasible. Provision of internal and external views of nature, 'positive' distractions, and visually appealing aesthetics are also desirable.

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The importance of of IEQ and productivity

Breakdown of human activity location
Source: The US National Human Activity
Pattern Survey (Klepeis et al. 2001)

Breakdown of typical business costs
Source: Browning and Romm (1994)

The characteristics of indoor spaces can have a significant impact on people, who spend much of their time indoors (top figure on the left). As a result, good IEQ has wide-reaching real and potential benefits to building occupants, employers and building owners. These benefits include:

The bottom line of most of these benefits is the potential for improved productivity, which arises at many levels, from the individual occupant, through to improved business performance and output, and the wider workplace in general.


Potential productivity gains in Australia from improved indoor environments

Source of productivity gain Potential annual savings or gains
Reduced respiratory illness $1-$2 billion
Reduced allergies and asthma $0.1-$0.5 billion
Reduced SBS symptoms $1.1-$3.5 billion
Increased work performance (improved thermal, lighting, acoustics) $2-$15 billion
Total $4.2-$21 billion

Source: Adapted from Fisk (2002)

Further reading:

The dollars and sense of green buildings
Green building costs and financial benefits
How IEQ affects health and productivity
A model to estimate the cost-effectiveness of indoor environment improvements in office work


Commercial motivations

As well as the obvious human benefits of improved IEQ, significant business and commercial benefits can also be derived from the overall building environment and what it signals to workers and visitors about organisational values and aspirations. These factors are more elusive and are likely to be heavily influenced by organisational policies and culture, as well as by the physical setting. The potential business benefits of improving IEQ include:

Attracting and maintaining high quality workers

There is growing evidence that buildings are used strategically as a sales and marketing tool (Petzinger, 1997) and as an employee 'benefit' to attract and retain high quality workers (Becker & Lynn, 1986; Leiber, 1998). In addition, the building itself as a symbol of the corporation's environmental and social performance may be a powerful attraction for potential employees (see studies reviewed in Turban & Greening, 1996). It is not clear from the research, however, how much improved interior quality and sustainable design contribute to attracting high quality workers relative to other building factors. However, more employees are requiring that the values of the organisations in which they work (such as commitment to sustainability and healthy workplaces) align with their own values.

Improved organisational image

There is a growing recognition that green buildings may play a significant role in promoting the organisation as a whole. A recent survey by BOMA International and the Urban Land Institute (Baier, 1999) found that 72% of building tenants surveyed about building quality placed a high importance on building image. A study of the first LEED (Leadership in Energy and Environment Design) Platinum building in the United States, the Philip Merrill Environmental Center in Annapolis, Maryland, found that the environmental values conveyed by the building and by the restoration of the site had a powerful influence on occupant responses to the organisation and its work environment.

Increased individual productivity

There is mounting evidence that there is a clear economic motivation for ensuring high indoor environment quality. Wyon (2004) reviewed recent research findings and concluded that it was now beyond reasonable doubt that poor indoor air quality in buildings decreased worker productivity and caused visitors to express dissatisfaction. The size of the effect on most aspects of office work performance was as high as 6-9%, the higher value being obtained in field validation studies. Wyon noted that it was usually more energy efficient to eliminate sources of pollution than to increase outdoor air supply rates, and that it was possible to make a cost-benefit analysis of either solution for a given building. Such analysis showed payback time could be as low as two years.

Occupant questionnaires conducted by Building Use Studies, based on simple ratings of perceived productivity, show that the overall effect of buildings on occupant productivity can range from a 20% gain to a 15% loss. However, most buildings fall into the +5% to -5% range, with about two-thirds having minus perceived productivity scores. It should be noted that this effect relates not only to IEQ variables, but to a range of other building issues, such as workspace design and facilities management response times, and that it is difficult to separate out the productivity impacts of IEQ and non-IEQ related issues.

Increased organisational level productivity

From a strategic perspective, improved individual output matters most if it has higher-level value. That is, to be beneficial to the organisation, increased personal productivity should translate to improved product quality, timeliness of output and increased innovation. A pre-post study of the Herman Miller Green House building in Holland, Michigan, showed modest increases in productivity that could be attributed to the building (Heerwagen et al., 1997). Using the organisation's internal productivity data, researchers found increases of 0.5% to 2.0% in several of the dimensions. Although the increases were fairly small, they nonetheless represent a competitive advantage in the marketplace. The small increases may be due to a ceiling effect: that is, the organisation may already be operating so efficiently that it is increasingly difficult to find additional ways to be efficient. Under such circumstances, enhanced strategic performance is likely to come from new products or product innovations, which take time to develop. In the Herman Miller study, TQM measures were tracked for just the year prior to and the year after the move.

Reduced illness and absenteeism

There is growing recognition of the large health and productivity costs imposed by poor IEQ in commercial buildings, particularly indoor air quality (Kats, 2003).

Fisk (2002) estimates that improved HVAC systems, which limit the spread of contaminants and pathogens, could reduce respiratory illnesses by 9-20%. In the US, the productivity increases from reduced absenteeism and illness could be as high as $6 billion to $14 billion from reduced respiratory disease; $1 billion to $4 billion from reduced asthma and allergies; and $10 billion to $30 billion for a reduction in symptoms associated with sick building syndrome (Fisk, 2002). When considered in an Australian context, this could result in potential productivity gains in excess of $4 billion (table titled 'Potential productivity gains in Australia from improved indoor environments' above).

Operational and maintenance cost savings

Improved IEQ has the potential to reduce building maintenance costs, through a reduction in occupant complaints about IEQ-related issues. According to a study by Federspiel (2001), based on 575 buildings in the USA, nearly one fifth of complaints to facilities managers were related to indoor environment issues. Most of these complaints were related to thermal comfort. Federspiel (2001) estimated the potential savings in maintenance costs from reduced thermal comfort complaints alone to be $0.0035/ft2 per year. However, this saving needs to be offset against any increased costs of providing higher quality IEQ, such as increased HVAC maintenance requirements.

Marketing potential

In an article on the competitive advantage of sustainability, Hart (1995) saw sustainable market development as a major driver of economic benefits. With respect to corporate environmental performance, Hart wrote that 'market research suggests there is a vast amount of unclaimed reputation space'. Although this is true for all green buildings, regardless of IEQ, provision of a high-quality working environment has a similar amount of 'unclaimed reputation space' to be used as a marketing tool.

Lower insurance costs

A 1998 study by researchers at the Lawrence Berkeley National Laboratory assessed costs to the insurance industry associated with poor indoor air quality and litigation, including health care insurance payments and professional liability claims. Although they turned up little specific information about costs to insurance companies, they concluded that 'there is a strong awareness and growing concern over the "silent crisis" of IAQ and its potential to cause large industry losses, and that a few companies are taking steps to address this issue' (Chen & Vine, 1998). They also concluded that energy-efficient building improvements have insurance loss reduction implications due to their potential to improve indoor air quality.

Legal risks

The NSW Legislative Assembly (2001) produced the Report on Sick Building Syndrome, in which it summarised many legal cases based on poor indoor environments. These were as follows:

United States

Case One: In a US Environment Protection Agency case, it was reported that an award of nearly $1 million damages was made by a jury to five employees of the Agency. This was compensation for health impairment attributed to occupancy of its head office in Waterside Mall in the late 1980s, when carpet replacement was undertaken while normal work in the building continued. It was reported that a further 14 cases were awaiting hearing. Compensation costs were additional to the cost of evacuating and relocating 8,000 employees to temporary accommodation and the remedial work required in the building.

Case Two: A large court house complex in Florida was evacuated, and court activities were carried on in temporary premises for many months, while extensive rebuilding was carried out to remedy defective workmanship that allowed entry of moisture and colonisation by moulds and fungi. It is understood that the cost was more than $US20 million. This was considered to be the first sick building syndrome case in the US, with the following details:

The plaintiff's case arose from alleged injuries suffered from contamination of the indoor air caused during tenant improvements to an office building. Seven building occupants claimed indoor air pollution resulted in personal injury including temporary and permanent health problems. The two companies for whom they worked claimed business losses as a result of exposure to the pollutants.

The plaintiffs alleged that:

  • VOCs entered and occupied spaces on the same floor from construction of ductwork containing solvents
  • insufficient supply of outside air (not related to renovation work) had contributed to elevated VOC levels.

The defendants included:

  • the insurance company (representing the developer and building owner)
  • the property management company
  • the construction manager
  • the architectural firm (designers of core and shell building)
  • the tenancy improvement contractor
  • the mechanical (air-conditioning) contractor for the tenant improvements.

It should be noted that additional defendants including the lease-building contractor, the tenant improvement space planning consultants, and the indoor air quality consultants who investigated the original complaints settled with the plaintiff at an early stage of the proceedings. After testimony by only one third of the plaintiff's expert witnesses, the parties reached a monetary settlement believed to be seven figures.

Australia
A number of cases which relate to illness from poor indoor air quality have been decided in Australia:

  • Bishop v Commonwealth of Australia (1982): This case 'established that air quality within a building can be the subject of a compensation order and that the aggravation of a pre-existing allergy is not a bar to compensation'.
  • Glover v Australian Telecommunications Commission (1984): Compensation was not awarded in this case. However, the case noted 'that a disease aggravated by conditioned air could be the subject of a compensation order, if sufficient evidence of the link between air quality and illness was presented'.
  • Carey v Australian Telecommunication (1985): A Commonwealth employee sought compensation before the Federal Administrative Appeals Tribunal under the Compensation (Commonwealth) Government Employees Act 1971. Here, a postal clerk with a history of asthmatic complaints complained that on moving to an air-conditioned building, his condition noticeably deteriorated. The Tribunal found that the applicant had presented sufficient evidence. He demonstrated a genuine respiratory condition, and presented evidence that moulds and dust found in the building's air-conditioning system had aggravated his condition.
    Telecom presented evidence that the air-conditioning system had been well-maintained and clean. On this point, the Tribunal said:
    'Irrespective of the state of maintenance and cleanliness, the fact is that certain moulds, fungi and other substances are being circulated by the system and, for whatever reason, they have an adverse effect on the applicant ... If every component was cleaned daily, if every nut and bolt was tightened regularly, if the system was a paragon of punkahs, he would still be incapacitated.'
    In the Tribunal's view, liability under the Act was strict and, once the causal connection was made between the applicant's illness and the building's air-conditioning system, liability accrued regardless of measures taken by the employer.* Accident Compensation Commission (Victoria College) v Bradley (Judge Bradley, Accident Compensation Tribunal of Victoria, 1989): This case was very similar the one outlined above. The applicant was a TAFE librarian, who claimed under the Accident Compensation Act 1984 (Victoria).
    Evidence was presented to the effect that the applicant was highly sensitive to air contamination. The aggravation of her condition was due to recirculation through the building's air-conditioning system of formaldehyde fumes from building materials in a new library building.
    The levels of formaldehyde were within acceptable standards but the judge was satisfied as to the causal connection between the applicant's injury and the building's air-conditioning system, and, under the Act, liability was strict. Although Carey was not cited, the principles of that case were used.
    The case is notable in that Mrs Bradley cited sick building syndrome as one of her conditions in her statement claiming compensation. This was quite possibly the first claim of its kind in Australia.
  • Favell Mort Limited v Murray (1975): This case touched on the subject of diseases contracted in buildings. An employee of the company had contracted mengo-encephalitis, possibly during a flight back to Australia, during the course of his employment. Barwick CJ made the following statement:
    'Had he been required by his employment to be at some particular place in a confined area, such as a building, and he was there attacked by a virus with the consequence experienced by him in this case, there would not seem to me to have been the same difficulty in accepting that he received the virus at the place where his employment required him to be and that, in consequence, that obligation of his employment contributed to his injury in the extended meaning of the word.'
    Again, this supports the view that diseases contracted in a building can be the subject of a worker's compensation claim. It was also the first High Court reference to a building-related illness.
  • Western Suburbs Hospital v Currie (1987). The Court decided that the hospital owed a duty of care to patients and visitors. The DHAC report noted that there were few recent cases from which to draw legal interpretation since most were being settled out of court, preventing legal precedent.

The legal framework in Australia that underpins such cases was also summarised by the NSW Legislative Assembly. While specific to NSW, the situation is expected to be similar in other states and territories. Also, in overview, there is a legal risk inherent in the process for all those involved in the construction and management of buildings. Litigation, liability and legal precedent can ensue through common law avenues to:

  • the building owners and managers
  • employers or other occupiers of premises
  • architects, engineers and others involved in the design and construction of the premises
  • manufacturers of relevant equipment
  • contractors or others involved in the maintenance of the equipment.

These people are subject to a duty of care to take all reasonable steps to see that those who may be affected by their acts or omissions are not put at risk of reasonable foreseeable injury, loss or damage by the way in which they conduct themselves.

IAQ actions to establish liability have occurred in the following areas:

  • breach of statutory obligations under workers' compensation and occupational health and safety and, increasingly, environmental legislation
  • torts of negligence or nuisance (common law)
  • occupier's liability
  • strict liability under certain statutes
  • breach of warranty, particularly in relation to new buildings and their services such as ventilation, cooling and heating systems
  • breach of Trade Practices legislation.

The burden of proof is greater in the common law areas, such as negligence, than in statutory areas, such as workers' compensation. As a consequence, most cases decided to date have dealt with occupational air quality issues.

NSW Occupational Health and Safety Act
The Occupational Health and Safety Act 1985 imposes obligations on an occupier of a workplace to ensure that the workplace and the means of access to and egress from the workplace are safe and without risks to health. The clear reference to the 'health' of employees in the Act (clause 15) is important in this discussion.

An occupier is a person responsible for the management or control of the workplace. That may vary from part to part of the workplace, and may include not only the employer, but also a landlord and managing agent.

Regulations made under the Act may also impose more precise duties on various parties relevant to the IAQ of premises. For example, the Asbestos Regulations impose duties on employers and occupiers of premises to ensure that the workplace and plant are designed and constructed to be free of asbestos or without risk to health from it. This imposes particular obligations for the assessment and control of risk from asbestos.

Common law
The considerations referred to in relation to the occupier's liability provisions apply equally to the common law duty of care. However, the following should be noted:

  1. While the occupier's liability provisions relate only to the state of the premises, the common law duty of care is much wider and relates also to the use of the premises.
  2. The occupier's liability provisions relate only to an occupier of the premises, whereas the common law duty of care applies also to those involved in the design, construction and maintenance of the premises.

Obstacles identified as hampering common law claims include:

  • a lack of conclusive scientific or medical evidence
  • the presence of consistent actions to the illness and pre-existing conditions
  • the cost of litigation and delays
  • the difficulty in proving that a defendant reasonably foresaw the damage that could occur
  • the difficulty in proving that a duty of care was owed to the plaintiff.

Disability discrimination
Federal and state legislation exists that renders it unlawful for a person to discriminate against another person on the grounds of the other person's disability. Under the Commonwealth Disability Discrimination Act 1992, those making premises and the facilities within in them available to the general public, or a section of the general public, are also required to provide that same access to people with disabilities (there are exceptions based on inappropriate design and construction elements and hardship caused by alteration costs).

In NSW, the Disability Discrimination Legislation Amendment Act 1998 amends various other pieces of state legislation so as to provide consistency with the Commonwealth legislation. A NSW nightclub operator was recently found to have breached the disability discrimination provisions. A person with asthma complained of being unable to remain in the nightclub because of the environmental tobacco smoke from fellow patrons. This is an example of IAQ being an element of the provision of access to premises and facilities, providing a potential liability to damages (in this case $2,000) for the occupier.

Occupier's liability
The occupier's liability also accrues under the provisions of the Wrongs Act 1958. This imposes a duty on an occupier of premises to take care, in such circumstances as are reasonable, to see that any person on the premises will not be injured or damaged by reason of the state of the premises, or of things done or omitted to be done in relation to the state of the premises. This would seem to relate to IAQ.

An occupier of a premise who would be subject to this duty of care includes a landlord who:

  • is under an obligation to the tenant to maintain or repair premises
  • is, or who could put themself, in a position to exercise a right to enter on the premises to carry out maintenance or repairs.

In determining whether or not the duty of care has been discharged, a number of factors are set out in the Act, which relate to:

  • the gravity and likelihood of the probable injury
  • the nature of the premises
  • the characteristics of the person entering the premises and their ability to appreciate the danger
  • a balance of the burden eliminating the danger compared with the risk of the danger to the person.

Lower future regulatory compliance costs

Regulatory requirements for IEQ are poorly specified at present, although this is likely to change in coming years as sustainable building practices are implemented in regulations. At present, the Building Code of Australia has requirements for the provision of adequate ventilation and for microbial control in water and air handling equipment. Also, 'duty of care' regulations impose requirements on building owners to protect building occupants from harm. ABCB are currently considering the future of regulations in the IAQ and IEQ domain. Any future regulatory changes have the potential to result in compliance costs, and these will clearly be higher for buildings with poor IEQ.

Regulations

There are a range of government regulations that may impact on IEQ in Australia, although usually without explicit reference to IEQ. It is likely that this will change in coming years as building codes introduce requirements to substantially improve the sustainability of commercial buildings. Current regulations in Australia take the form of:

  • building codes, which require ventilation to achieve 'acceptable' air quality in buildings
  • local government codes, whereby one building owner cannot create an odour that impacts on adjacent buildings
  • 'duty of care' regulations, by which building owners must protect building occupants from harm
  • occupational health and safety regulations, by which employers must provide 'safe' workplaces for employees
  • national environmental protection measures, which require health-based air quality standards be met for urban air (by regulation, the measures do not extend to indoor air).

These policies, regulations and standards are examined in more detail according to various IEQ components:

IEQ and green buildings

A comparative evaluation of green and conventional buildings, based on post-occupancy surveys, has been recently undertaken in Australia ('Green' buildings - What Australian building users are saying). The study identified associations across all buildings between perceived productivity and overall comfort (lighting, ventilation, thermal comfort and noise), as well as perceived productivity and thermal comfort in particular. The study found that while the best green buildings consistently outperformed the best conventional buildings from the occupants' perspective, the first generation of Australian green buildings may be underperforming on some IEQ variables (such as thermal comfort conditions in the summer). However, they still perform better on non-IEQ aspects, such as 'meeting needs'. The most serious consequence of poor summer time conditions is the effect on perceived productivity at work. The researchers expect this to change as feedback from green building performance is incorporated into the next generation of designs.

The main conclusions from the survey include:

  • A wider spectrum of performance is evident in green buildings, with the best outperforming conventional buildings.
  • Thermal comfort conditions in summer are generally poor, although there are some notable exceptions.
  • Winter conditions can often be too cold.
  • Ratings for design, image, health and needs are usually better in green buildings.
  • Perceived productivity scores are marginally lower on average, but a number of successful green buildings surpass conventional ones.
  • Occupants seem to be more tolerant.
  • Ratings for lighting are good.
  • Internal noise is often worse.

The outcomes for the first generation of green buildings in Australia appear to indicate that good intentions outstrip performance. However, it should be noted that many of these buildings were developed without the frameworks and guidelines that are available today, and without the benefit of lessons from preceding buildings.

Similarly, a US study (Occupant satisfaction with indoor environmental quality in green buildings) concluded that although occupants rated the IEQ of green buildings higher overall than that of conventional buildings, no clear relationship was found between IEQ 'rating points' and occupant satisfaction with IEQ. This suggests that, by itself, being 'green' does not guarantee better IEQ.

Opportunities for improved performance

A fundamental principle for good IEQ design of new and existing buildings is that the provision of high-quality environments for indoor air, thermal comfort, lighting and noise should be considered when design and operational decisions are made. Apart from the technical requirements imposed by this approach, there are key organisational matters that need to be addressed to ensure the integration of IEQ into the building design, operation and maintenance.

As a general rule, occupants want their perceived needs to be met quickly and with as little intervention by themselves as possible. They normally respond well to IEQ features that reduce discomfort and distractions, as well as those that enable more choice and control over their environment. Users tend to be more tolerant if they understand how things are supposed to work, and if they have a degree of control over them. Controls should clearly communicate to the user what they are for and how they are supposed to operate. They should provide feedback to the user that they have operated successfully after being used, and, crucially, give some indication that something has happened as a result. Some of the key opportunities for improved performance are addressed in the following sections:

IEQ management

The establishment and implementation of IEQ management plans is recommended to help maintain high-quality IEQ and a high level of occupant satisfaction with IEQ. Elements of an IEQ management plan include:

  • selecting an IEQ manager
  • identifying an IEQ profile
  • assigning responsibilities and training staff
  • developing an IEQ check-list
  • inspecting the building and HVAC system on a periodic basis
  • facility operation and maintenance to maintain IEQ
  • developing specific procedures to record and respond to occupant complaints
  • identifying special practices to maintain IEQ during building renovation, painting, pesticide use, or other periods of high indoor pollutant generation
  • maintaining IEQ documentation.

The principles that underlie such a process are provided in a guidance document prepared by the US Environmental Protection Agency and The National Institute for Occupational Safety and Health (USEPA/NIOSH, 1991). A more recent Australian perspective has also been provided by AIRAH (2004).

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Indoor air quality

Indoor air quality (IAQ) refers to the totality of attributes of indoor air that affect a person's health, well-being and comfort.

IAQ is characterised by:

  • physical factors, such as ambient temperature, humidity and ventilation rates
  • air pollutant factors, such as pollutant levels and exposure times
  • human factors, such as occupant health status, individual sensitivity and personal control.

Major contributors to poor IAQ include:

Potential sources of indoor air pollution
Source: Brown (1997)


Other factors that may contribute to poor IAQ include poor cleaning practices, poor moisture control (e.g. water leaks or persistent damp surfaces), human occupancy effects (e.g. odours), poorly designed enclosed garages and poor building maintenance.

Assessment of IAQ and its impact on human health requires consideration of a number of issues, including ventilation, temperature and humidity, levels of air toxics, and the presence of respirable particles and fibres, environmental tobacco smoke, micro-organisms, carbon monoxide and nitrogen oxides.

Improved IAQ can be achieved by:

IAQ is currently (or likely to be in the future) covered by a range of air quality policies, regulations and standards.

Further reading:
Air toxics and indoor air quality in Australia

AIRAH (2001), HVAC&R maintenance report AIR-DA19-2001, Melbourne: Australian Institute of Refrigeration, Air Conditioning and Heating

AIRAH (2004), Indoor air quality report AIR-DA26-2004, Melbourne: Australian Institute of Refrigeration, Air Conditioning and Heating.


Contributors to poor indoor air quality

New building materials

Volatile organic compounds (VOCs) can be found in many places inside buildings (e.g. building materials, consumer products, cleaning materials and office equipment) (Brown 1997). It is clear from building surveys that VOC concentrations are substantially higher in new buildings than in established buildings. This elevation persists for some months after building construction (Brown et al., 1994) and is associated with occupant illness, including sensory irritation, headaches and lethargy (Molhave & Nielsen, 1992; Norback & Edling, 1991). Building materials, particularly wet or semi-dry products such as paints and adhesives, are implicated as the major VOC sources in new or renovated buildings due to their high VOC emission rates and large surface areas (Brown et al., 1994). Emission of formaldehyde gas from reconstituted wood-based panels (RWP), such as particleboard and medium-density fibreboard (MDF), into the air of buildings constructed with these products has been a concern of industry and environmental scientists for several years (Brown 1997). Building surveys have shown that high concentrations of formaldehyde occur in indoor air when large quantities of RWP products are installed in buildings, especially in mobile buildings. For Australia, the DHA NICNAS (2006) currently recommends an indoor air quality goal for formaldehyde of 100 µg/m3 (ceiling limit (0 °C, 101 kPa). It also recommends improved control of potentially harmful building materials.

New furniture

Furniture is constructed from many of the same or similar materials as used in building construction (e.g. coatings, adhesives and wood-based panels) and thus contributes to the indoor air load of VOCs and formaldehyde (Brown 1999a). The proportional contribution will vary from case to case, but pollutant emission limits for furniture should be used to control indoor air pollution, just as for building materials. A code for assessing office furniture emissions was developed by government and industry in the USA (BIFMA 2001). It recommended:

  • a room environmental chamber, to provide a simulated but inert environment for furniture testing (23 °C ± 0.3 °C, 50% ± 5%RH, air exchange rate 1.0 ± 0.05 /h)
  • that new furniture items be assessed (as an aggregation of items that amounted to a surface area of 25.8 m2 in a 30.5 m3 chamber) approximately three weeks after unwrapping, to simulate the delay prior to occupant exposure
  • that the new furniture meet chamber concentrations of formaldehyde (60 µg/m3) and TVOC (500 µg/m3).

Office equipment

Several surveys of building occupants have identified an association between sick building syndrome and the presence of office equipment (Brown 1999b). A range of pollutants is known to be emitted from photocopiers, such as VOCs, ozone, respirable particles, formaldehyde and nitrogen dioxide, but there has been only limited effort to measure and quantify pollutant emissions from office equipment (Leovic et al., 1995; Brown 1999b). Brown (1999b) showed that VOCs and respirable particles were the dominant emissions, with VOC levels related to the number of copies produced (i.e. emission should be measured as pollutant mass per copy), while particle emissions consisted of residues released from equipment as well as particles released by the copy process. Recently, He et al. (2007) have shown that ultra-fine particles are released from office printers.

The identification of low-emitting office equipment appears to be somewhat distant. The best current practice is to place the equipment in a separate room with a fan exhaust or to connect an air-cleaning device (with verified effectiveness) to the office equipment exhaust.

HVAC system performance and maintenance

Poor operation and maintenance of ventilation systems can lead to problems, resulting in poor IAQ. Problem areas include:

  • build-up of moisture, leading to microbiological growths
  • duct cleanliness
  • transmission of particles
  • quality of outside air used for ventilation.

A written plan for periodic maintenance of the ventilation system should be developed and followed, and maintenance activities should be documented — for more details, refer to AIRAH (2001, 2004).

A practical aspect of ventilation system maintenance is duct cleaning, although the need for and benefit of this practice is open to question. Dust build-up occurs within ducts (usually made from sheet metal and covered with insulation) because particles in the air supply naturally deposit in small amounts on indoor surfaces. Until the deposition grows significantly enough to affect airflow rates (by reducing the cross-section of the duct) or to be released again by air turbulence, or unless moisture transport to the duct interior leads to microbiological growths, there appears to be little benefit from duct cleaning in most commercial buildings. The usual appearance of particles on ceiling surfaces adjacent to air inlet diffusers is more likely to be an extension of the dust deposition process beyond the ductwork. However, duct cleaning may be needed in mechanical ventilation systems for hospitals and food processing plants where more sterile surfaces are required.

Cooling towers may also affect IAQ if air contaminated with Legionella bacteria is able to find its way into buildings. Water cooling towers must be located well away from building air inlets, and are subject to rigorous requirements for chemical treatment, monitoring, cleaning and registration in some states (AS 3666 Air-handling and water systems of buildings – microbial control).

Further reading on this subject can be found in AIRAH DA26: Indoor air quality manual (AIRAH, 2004) and AIRAH DA19: HVAC maintenance (AIRAH, 2001).

Assessment of indoor air quality and human health effects

In order to measure and assess indoor air quality, it is necessary to have an understanding of the threshold levels at which exposure to various toxics and pollutants can affect human health.

The table titled 'Indoor air, ambient air and occupational exposure goals for air contaminants' provides a summary of the maximum recommended occupational and environmental exposures to various toxics. These are based on recommendations from the following organisations:

  • the National Health and Medical Research Council (NHMRC), which recommended health-based advisory IAQ goals for several pollutants up to 2002, when they were rescinded. However, the goals are still accessible at <http://www.nhmrc.gov.au/publications/synopses/eh23.htm>
  • the National Occupational Health and Safety Commission (NOHSC), recently renamed the Australian Safety and Compensation Council, which provides exposure guidelines for a large number of air contaminants in workplaces that are generally called up in OH&S regulations
  • the National Environment Protection Council, which established health-based National Environment Protection Measures (NEPMs) for urban air contaminants. By regulation, NEPMs are applicable only to urban air, but since they are health-based criteria, their application to indoor air is considered reasonable (although not necessarily representative of all indoor air pollutants)
  • the World Health Organization (2000), which has recommended health-based environmental air quality guidelines for Europe that are applicable to both urban air and indoor air exposures.

The table titled 'Indoor air, ambient air and occupational exposure goals for air contaminants' below shows that there are substantial differences between occupational and environmental requirements (National Health and Medical Research Council, 1996). These differences arise because:

  • occupational exposures occur for approximately 40 hours per week, whereas environmental exposures occur continuously (i.e. 168 hours per week, 4 times higher than occupational exposure)
  • the population health demographic of the workforce differs considerably from that of the general population, as the latter includes sectors with specific sensitivities to pollutants (see sensitive population sectors). Infants and children are more vulnerable to respiratory illnesses associated with environmental tobacco smoke, house dust mites and gas combustion products, such as nitrogen dioxide. Asthmatics are sensitive to a variety of pollutants that act as inducers and triggers.

Therefore, the protection of sensitive sectors of the population is considered appropriate when selecting IAQ guidelines for residential, health and educational buildings. Indicators for other building classes, especially office buildings, will need to consider the likely access to them by sensitive sectors of the population. For example, a government office to which the general public has access will need to apply environmental guidelines, while a private office accessible only to employees may choose to apply occupational guidelines, depending on the health status of its employees.

Based on these considerations, metrics for specific pollutants within an occupied office building, in relation to health-based criteria, can be developed. These are presented in the table titled 'IAQ metrics and criteria' below. In addition to use of these criteria, an IAQ comfort-based questionnaire of occupants is recommended since there may be indoor air pollutants that are not yet understood for their impacts on occupant well-being and comfort.

Assessment of IAQ and its impact on human health requires consideration of a number of issues, including:

Indoor air, ambient air and occupational exposure goals for air contaminants


IAQ metrics and criteria


Ventilation

Historically, building ventilation rates have been set at levels that reduce the 'stuffiness' of indoor air due to human bio-effluents. Humans release a variety of odorous and gaseous bio-effluents (e.g. body odours), which influence the perceived acceptability of indoor air. Until recent years, most standards and guidelines for minimum ventilation rates in buildings were based primarily on the ventilation needed to maintain indoor air considered acceptable by a large proportion (e.g. 80%) of visitors when they initially entered a space where occupants were the only indoor pollutant source. For example, Australian Standard AS 1668.2 Mechanical ventilation for acceptable indoor air quality (1991) is called up in the Building Code of Australia in relation to ventilation, with outdoor air at rates based on such acceptance. Ventilation rates are specified in different room and building types, generally in the range of 7.5--30 litres of outdoor air per second per occupant. A level of 10 litres of outdoor air per second per occupant is specified for offices. Now, however, concerns about other sources of odours and adverse health effects from air pollutants are increasingly influencing building ventilation standards.

Carbon dioxide

Carbon dioxide (CO2) is one of the gaseous (but non-odorous) human bio-effluents in exhaled air.  Humans are normally the main indoor source of carbon dioxide. Unvented or imperfectly vented combustion appliances can also increase indoor CO2 concentrations. The outdoor CO2 concentration is approximately 380-400 ppm, whereas indoor concentrations are usually in the range of 500 ppm to a few thousand ppm. At these concentrations, CO2 is not thought to be a direct cause of adverse health effects. However, CO2 is an easily measured surrogate for other occupant-generated pollutants, such as body odours, and so can be used as an indicator of the rate of outside air supply per occupant (ASTM, 2002). If the number of occupants and the rate of outside air supply are constant and the CO2 generation rate of occupants is known, the rate of outside air supply per occupant is related to the equilibrium indoor CO2 concentration in a straightforward manner, as predicted by a steady-state mass balance calculation (Persily & Dols, 1990). However, in many buildings, CO2 concentrations never stabilise during a workday because occupancy and ventilation rates are not stable for a sufficient time period. If the CO2 concentration has not stabilised at its equilibrium value and the steady-state relationship between CO2 and ventilation rate is used to estimate the rate of outside air supply, the estimated outside air ventilation rate will exceed the actual rate. 
Many studies have led to the conclusion that 7.5 L/s of outdoor air ventilation per person will control human body odour such that roughly 80% of un-adapted persons (visitors) will not find the odour unacceptable. These studies also showed that the same level of body odour acceptability was found to occur at a CO2 concentration of about 650 ppm(v) above the outdoor concentration. Thus, if the equilibrium CO2 concentration is 1000 ppm or less when the building is fully occupied, then the rate of outside air supply per occupant is approximately that required to control occupant odours (ASTM, 2002). However, CO2 concentrations do not provide information on the control of contaminants from other indoor pollutant sources (such as building materials, furnishings and occupant activities) or from outdoor sources. Air quality may not be acceptable if there are other sources of sensory pollutants in the building. In addition, there may be other pollutants that are not sensory irritants, but which have adverse health effects on the occupants. In response to this, regulations now typically contain methods for estimating ventilation requirements that incorporate building-related pollution.

Temperature and humidity

Air temperature and humidity influence perceptions of the quality of indoor air and the level of complaints about non-specific, building-related health symptoms (often called sick building syndrome symptoms). Higher air temperature has been associated with increased health symptom prevalence in several studies (Skov et al., 1989; Jaakkola et al., 1991; Wyon, 1992; Menzies et al., 1993).  Occupants' perceived acceptability of air quality has been shown to decrease as temperature and humidity increase in the range between 18 °C, 30% RH and 28 °C, 70% RH (Fang et al., 2004; Molhave et al., 1993).

VOCs

Indoor air typically contains dozens of volatile organic compounds (VOCs), at concentrations that are measurable but greatly below occupational exposure goals. VOCs are emitted indoors by building materials (e.g. paints, particle boards, adhesives etc.), furniture, equipment (e.g. photocopying machines, printers etc.), cleaning products, pest control products, and combustion activities (e.g. cooking, unflued gas heaters and stoves, tobacco smoking and enclosed garages). The table titled 'IAQ metrics and criteria' above shows some, but not all, of the VOCs emitted (Brown 2000). Humans also release VOCs as a consequence of their metabolism and through the use of personal products, such as perfumes. The outdoor air also contains VOCs (mostly from automobile exhausts) that enter buildings, especially near busy roads. While uncommon, VOCs in contaminated soil adjacent to a building can also be drawn indoors.

New building materials and furnishings generally emit VOCs at a much higher rate than older materials. Emission rates for many VOCs (and, by consequence, indoor air concentrations) may decline by an order of magnitude during the first few weeks after the materials are installed in the building. However, the emission rates of some organic compounds (such as formaldehyde emissions from pressed wood products) decline much more slowly. Because of concerns about the health effects of VOCs and formaldehyde, many overseas manufacturers, and some Australian manufacturers, have worked to reduce the VOC emissions of their products and now market 'low emission' interior paints, wood panels and carpets. A key factor here is the definition of 'low emission', since there are different descriptors of this property in each country (Brown & Johnson, 2004).

Despite the uncertainty and variability regarding health effects from VOCS, total VOC concentrations above one or two milligrams per cubic metre may increase the likelihood of health effects in some occupants.

Some VOCs are suspected or known carcinogens or causes of adverse reproductive effects. Some VOCs also have unpleasant odours or are irritants. Some research studies have linked VOCs to non-specific health effects, typical of sick building syndrome. The total VOC (TVOC) concentration, often used as a simple, integrated measure of indoor pollution by VOCs, is defined as the total mass of measured VOCs per unit volume of air, exclusive of very volatile (e.g. formaldehyde) organic compounds. Laboratory studies in which humans were exposed to TVOC mixtures under controlled conditions (Molhave et al., 1993) documented increased health effects (such as headaches, lethargy and irritation) at TVOC concentrations of the order of milligrams per cubic metre of air — orders lower than levels causing irritancy by individual VOCs. As an indicator of health effects, the TVOC concentration is inherently flawed because the potency of individual VOCs to elicit irritancy symptoms varies by orders of magnitude. The potency for other potential health effects, such as cancer or reproductive-related symptoms, is also highly variable between compounds.

Formaldehyde

Formaldehyde is a VOC of particular concern, as it is a widespread indoor air irritant that is also carcinogenic. Exposure to formaldehyde irritates the eyes, nose and throat, and can cause skin and lung allergies. Formaldehyde is classified by the NOHSC as a Category 2 carcinogen (a substance that should be regarded as if it is carcinogenic to humans). Likewise, the IARC (2006) classifies formaldehyde as carcinogenic to humans (Group 1). An extensive review of formaldehyde in Australia (Department of Health and Ageing NICNAS, 2006) concluded that:

  • Humans experience sensory irritation (eye, nose and respiratory tract irritation) at levels in air of 0.5 ppm formaldehyde and above, but available data do not allow identification of a definitive no-observed-effect level (NOEL).
  • Available human and animal data indicate gaseous formaldehyde is unlikely to induce respiratory sensitisation. Lung function tests suggest that asthmatics are no more sensitive to formaldehyde than healthy subjects. Limited evidence indicates that formaldehyde may elicit a respiratory response in some very sensitive individuals with bronchial hyperactivity, probably through irritation of the airways.
  • Based on available nasopharyngeal cancer data, formaldehyde should be regarded as if it may be carcinogenic to humans following inhalation.
  • An appropriate indoor air guidance value for formaldehyde is 0.1 mg/m3  or 0.08 ppm (sampling over a short duration, such as hourly), based on sensory irritation.
  • Standards Australia should (a) develop standards for mobile and relocatable buildings with guidance on ventilation and use of pressed wood products with low formaldehyde emissions, and (b) adopt international testing and labelling practices for assessing emissions of formaldehyde from materials, which allow for testing to low emission levels as provided in other countries, such as Japan.

Respirable particles

Respirable particles are particles below 10 µm in aerodynamic diameter, which deposit in the lower regions of the lung (the alveoli), where lung clearance mechanisms are slow. These are present in outdoor air and are also generated indoors from a large number of sources, including tobacco smoking and other combustion processes. Some particles and fibres may be generated by indoor equipment (e.g. copy machines and printers), and mechanical abrasion and air motion may cause particle release from some indoor materials.  Particles are also produced by people (e.g. skin flakes are shed and droplet nuclei are generated from sneezing and coughing).   
Some respirable particles may contain toxic chemicals. Particles that are biological in origin may cause allergic or inflammatory reactions or may be a source of infectious disease.  Increased morbidity and mortality are associated with increases of outdoor urban particle concentrations (NEPC, 2002). Of particular concern are those particles smaller than 2.5 µm in diameter, which are not only more likely to deposit deep inside the lungs but which are not readily removed by building filtration systems or by surface deposition (Environmental Protection Agency, 1996). In general, the large majority of indoor particles are smaller than 1 µm.

Particle composition is also an important factor. Particles may be inorganic or organic, solid or liquid aerosols, or they may be biological matter (see micro-organisms).

Fibres

Fibres in indoor air include asbestos and synthetic mineral fibres. The primary indoor sources are building materials, especially insulation products. Exposure to asbestos has been shown to cause lung cancer and other lung disease (Brown 2000). In the 1990s, exposure to synthetic mineral fibres (e.g. glass wool or rock wool) in industrial settings was associated with lung cancer. At that time, the International Agency for Research on Cancer (IARC) classified glass wool, rock wool, slag wool and ceramic fibres as Group 2B — possibly carcinogenic to humans. However, the IARC (2002a) has since revised this classification as follows:

  • refractory ceramic fibres are possibly carcinogenic to humans (Group 2B)
  • insulation glass wool, continuous glass filament, rock (stone) wool and slag wool are not classifiable as to their carcinogenicity to humans (Group 3).

In any case, a workplace exposure standard remains for these contaminants. Also, as synthetic mineral fibres can cause skin irritation, insulation products should not be exposed or unsealed within occupied zones.

Environmental tobacco smoke

Environmental tobacco smoke (ETS) is the mixture of pollutants caused by the smoking of tobacco indoors. Constituents of ETS include submicron-size particles composed of a large number of chemicals, plus a large number of gaseous pollutants. ETS from cigarettes is produced primarily by the smoke released at the burning end (sidestream smoke) and smoke exhaled by the smoker (mainstream smoke). The smoke is quickly diluted and dispersed in building air and changes rapidly in its physiochemical properties, especially in the decreased proportion of constituents found in the particle phase, relative to the vapour phase. Chemical composition also changes due to the way that constituents respond to ventilation and contact with indoor surfaces (Guerin et al., 1992).

An exposure standard for ETS has not been determined (NOHSC, 1994). However, several components have been measured as markers of ETS — most frequently combustion-derived particulate matter, since a high proportion of this is of respirable size. US studies have found respirable particle concentrations in the presence of ETS of 40-70 µg/m3 in homes and 200-350 µg/m3 in public entertainment areas (Spengler & Samet, 1991). Typical background levels in non-smoking office buildings have been estimated as a few tens of µg/m3, while typical levels in public buildings where smoking is permitted are up to 120 µg/m3 (Guerin et al., 1992). Australian measurements have largely been in recreational buildings, where elevated levels of respirable particles, nicotine and polycyclic aromatic hydrocarbons were observed (Brown, 1997).

As well as resulting in odour and irritation complaints, there is increasingly robust evidence that ETS causes significant adverse health effects (Environmental Protection Agency, 1992; California EPA, 1997). Chronic health effects of ETS exposure to adults include lung cancer and heart disease. The IARC (2002b) classifies environmental tobacco smoke as carcinogenic to humans (Group 1), based on evidence of lung cancer. Additionally, ETS exposure contributes to a variety of respiratory health effects in children, including asthma induction, asthma exacerbation, bronchitis, pneumonia and middle ear infection.

Micro-organisms

Many micro-organisms are approximately 1 µm and larger, with pollens often larger than 10 µm. Micro-organisms can be classified by their level of infectiousness:

  • Non-infectious micro-organisms include pollens, moulds, bacteria, dust mite allergens, insect fragments and animal dander. Their sources are outdoor air, indoor mould and bacteria growth, insects and pets. These micro-organisms may be brought into buildings as air enters, or may enter buildings attached to shoes or clothing and subsequently be re-suspended in the indoor air. The health effects of non-infectious micro-organisms include allergy symptoms, asthma symptoms and hypersensitivity pneumonitis, which is characterised by inflammation of the airway and lungs (Gammage & Berven, 1997).
  • Infectious non-communicable micro-organisms are airborne bacteria or fungi that can infect humans but that have a non-human source (Gammage & Berven, 1997). The best known example is Legionella, a bacterium that causes Legionnaire's disease and Pontiac fever. Cooling towers and other sources that aerosolise standing water (e.g. humidifiers) are the main sources of aerosolised Legionella in buildings. Legionella may also be present in potable water systems (due to dead-legs etc.), and may be spread through the aspiration of such potable water (e.g. through showers).  Some fungi from sources within a building can also infect individuals who are immune compromised.
  • Infectious communicable micro-organisms that are generated by one person may cause disease in others. These micro-organisms contain bacteria or a virus within small droplet nuclei produced from the drying of larger liquid droplets, often expelled during coughing or sneezing. Examples of respiratory diseases transmitted, at least in part, by micro-organisms include tuberculosis, influenza, measles and some types of common colds. Several studies, as reviewed in Fisk (2002) and Wyon (1996), have indicated that building characteristics may significantly influence the incidence of respiratory disease among building occupants.

Carbon monoxide

Carbon monoxide (CO) is present in outdoor air. Indoor concentrations may be higher than outdoor concentrations, due to indoor unflued combustion activities (e.g. unflued gas cookers and heaters), gaps in the exhaust ducts of vented appliances, and leakage of air from attached garages into the building. Tobacco smoking can also cause a small in