Firstly, What is Sick Building Syndrome
By definition:
Sick Building Syndrome (SBS) is a term used when building occupants experience health or comfort symptoms that appear linked to time spent in a building, but no single, specific illness or cause can be clearly identified.
From a technical perspective, what is Sick Building Syndrome?
We see the symptoms of Sick Building Syndrome in the occupants, a few examples include
Symptoms vary but often include:
- Headaches
- Eye, nose, or throat irritation
- Dry cough
- Dizziness or nausea
- Fatigue or lethargy
- Difficulty concentrating
- Skin irritation
- Sensitivity to odours
Most of these we could attribute to airborne particles or something based on the internal air of the building, or the indoor environment.
Fixing Sick Building Syndrome | Carbon Dioxide
When indoor carbon dioxide (CO₂) levels rise, occupants commonly experience fatigue, lethargy, and reduced concentration. In these conditions, no amount of coffee will restore alertness, the issue is environmental, not personal.
In most commercial buildings, the HVAC (air conditioning) system can adjust the ratio of recycled (return) air to outside (fresh) air. This capability exists primarily to conserve energy. For example, it is far more energy-efficient to cool 26°C return air than 35°C outside air. The same principle applies in motor vehicles when the air is set to “recirculate.”
To protect indoor air quality, engineering standards and design guidelines limit how much air may be recycled. Typically, around 30% outside (fresh) air must be introduced into the building during normal air-conditioning operating hours.
However, in practice, this balance can be altered. An overly enthusiastic building manager may reduce the outside air percentage to improve the building’s NABERS Energy rating. In addition, supply and return air fan speeds may be reduced to further cut energy consumption.
These two tactics—reduced fresh air intake and slowed air handling unit fans—are commonly observed in A- and B-grade commercial buildings. While they can improve measured energy performance, they often come at the expense of indoor air quality and occupant wellbeing.
The underlying driver is often financial: NABERS ratings directly influence a building’s perceived value and rental yield. The challenge is ensuring energy efficiency improvements do not undermine the health, comfort, and productivity of the people inside the building. (This is where an audit can have outcomes directly for the improved performance of the building at the tenant level).
Risk and Compliance Considerations for Property Managers
While reducing outside air intake and fan speeds may improve energy metrics, these adjustments carry material compliance and risk implications.
Australian Standards such as AS 1668.2 set minimum ventilation rates to maintain acceptable indoor air quality. Operating outside these parameters, whether intentionally or through poor system tuning, can expose building owners and managers to non-compliance risk, particularly if occupant complaints or health impacts arise.
Elevated CO₂ levels are a recognised indicator of inadequate ventilation. Persistent issues may contribute to fatigue, reduced productivity, and symptoms associated with Sick Building Syndrome, increasing the likelihood of tenant complaints, lease disputes, or requests for independent indoor air quality investigations.
From a Work Health and Safety (WHS) perspective, property managers have a duty of care to provide a safe indoor environment. Adjustments made solely for energy performance or NABERS outcomes must be balanced against occupant health obligations and documented operational intent.
Best practice is to:
- Verify outside air quantities against design and AS 1668.2 requirements
- Use CO₂ monitoring to validate real-world performance
- Ensure any energy-saving changes are engineered, documented, and defensible
- Avoid adjustments that compromise ventilation in occupied spaces
Energy efficiency and indoor air quality are not mutually exclusive—but unmanaged optimisation can quickly become a compliance issue.
Fixing Sick Building Syndrome | Poor HVAC System Maintenance
When the HVAC or air conditioning system is not properly maintained, several issues can directly impact occupants and tenants. Common examples include:
- Dirty or clogged air filters
Restrict airflow, reduce system efficiency, and allow dust and contaminants to circulate within occupied spaces. - Air loss through leaks or failed ductwork
Results in uneven temperatures, increased energy consumption, and reduced ability to maintain indoor comfort. - Inadequate fresh air intake
Can lead to elevated CO₂ levels, occupant fatigue, and complaints related to indoor air quality. - Poorly maintained coils and heat exchangers
Reduce heating and cooling capacity and place additional strain on mechanical components. - Faulty sensors, dampers, or controls
Cause systems to operate outside design parameters, leading to discomfort and unnecessary energy use. - Increased risk of system failure
Deferred maintenance often results in unplanned breakdowns, costly repairs, and tenant disruption.
Proper preventative maintenance not only improves occupant comfort and air quality but also helps property managers meet compliance obligations, control operating costs, and extend the lifespan of HVAC assets.
Risk & Compliance Considerations
Poor HVAC maintenance exposes building owners and property managers to several operational and compliance risks, including:
- Non-compliance with Australian Standards
Inadequate maintenance may result in systems operating outside the requirements of AS 1668 (Parts 1 & 2) for ventilation, indoor air quality, and smoke control. - Work Health & Safety (WHS) exposure
Poor indoor air quality, excessive CO₂ levels, or temperature extremes can contribute to occupant discomfort, reduced productivity, and potential WHS complaints or claims. - Increased tenant complaints and retention risk
Persistent comfort or air quality issues often lead to formal complaints, increased management time, and difficulty retaining tenants. - Higher risk of equipment failure and downtime
Deferred maintenance increases the likelihood of unplanned outages, which may breach service level expectations or lease obligations. - Energy efficiency and sustainability risks
Inefficient HVAC systems drive higher energy consumption, undermining NABERS, ESG, and sustainability performance targets. - Audit and insurance exposure
Inadequate maintenance records may leave owners exposed during audits, insurer reviews, or post-incident investigations.
A structured preventative maintenance program, supported by regular inspections and documented testing, helps mitigate these risks while ensuring regulatory compliance, occupant wellbeing, and asset longevity.
What’s Involved to fix Sick Building Syndrome?
You need a grounding point first, start with an Audit. Consider how the audit will work for you to achieve your goals and solve the major issues you are aware of. Make a short list of key performance indicators. A “random energy audit” is not enough, you need to be specific.
Overwhelmed With All the Issues.
It is easy to loose your way, especially in some of the larger “B” and “C” grade buildings built in the 79’s 80’s and 90’s. Consider these priorities:
- Safety
- Compliance (fire and elevators especially)
- Regular Costs to the Landlord (Gas and Power)
- Obsolescence (Serviceability, Energy & Maintenance of equipment)
- Aesthetics (The Landlord and leasing agents may want this first)
It is easy to be caught in a “fishbowl” and target everything under a given discipline, such as safety; this will be a disaster, target the major items, say great then $5000, then move to the next. At a later date, you can circle back to those smaller items and begin to tidy up.
Key Performance Indicators.
Make a short list of key performance indicators, if you make the list too long, you will be overwhelmed and lost, especially as day to day activities will interfere and grow.
Asset Register.
Tracking your opportunities to improve via an active asset register will keep you on track and avoid repeating works and assist with financial management and reporting.
