Indoor Air Quality and Healthier Homes
Indoor air quality is one of the most important parts of a healthier home. A home may look sustainable from the outside, but if the indoor air is stale, damp, polluted or poorly ventilated, it may not support the people living inside it as well as it should.
In a Green Star Homes context, indoor air quality sits within the wider idea of a healthy, resilient and positive home. It connects ventilation, airtightness, moisture control, material choices, cooking systems, combustion sources, filtration, daylight, thermal comfort and the everyday way a home is used. Green Building Council of Australia YourHome
Short answer
Indoor air quality matters because people spend much of their time inside homes. Good indoor air depends on controlled ventilation, moisture management, low pollutant materials, appropriate exhaust systems, reduced combustion sources and good building fabric design. In Green Star Homes, healthier indoor air supports comfort, wellbeing, resilience and better residential sustainability outcomes.
What indoor air quality means in a home
Indoor air quality refers to the condition of the air inside the home. It is affected by fresh air, stale air, humidity, dust, smoke, mould risk, off gassing materials, cleaning products, cooking emissions, outdoor pollutants, combustion appliances and the way air moves through the building.
Good indoor air quality does not happen by accident. It depends on how the home is designed, built and operated. Ventilation, airtightness, exhaust fans, window openings, materials, heating and cooling systems, moisture management and occupant behaviour all contribute to the final indoor environment.
A healthier home should not feel stuffy, damp or difficult to air out. It should be able to bring in fresh air, remove pollutants and manage moisture without undermining comfort or energy performance.
Why indoor air quality matters for Green Star Homes
Green Star Homes is built around positive, healthy and resilient homes. Indoor air quality is central to the healthy part of that framework, but it also affects resilience and energy performance.
A home with good indoor air quality can better support sleep, concentration, recovery, daily routines and long term comfort. A home with poor ventilation or moisture problems may feel uncomfortable and may increase the risk of mould, condensation, stale air and pollutant build up.
Indoor air quality also matters because sustainable housing should not only reduce environmental impact. It should improve the quality of life inside the home. A lower energy home that feels stale or unhealthy is not a complete residential performance outcome.
Ventilation is essential for healthy indoor air
Ventilation is the intentional introduction of outdoor air into a building. YourHome explains that all homes require ventilation to maintain good indoor air quality because ventilation increases oxygen levels and dilutes and displaces carbon dioxide and airborne pollutants. YourHome
In a home, ventilation may happen through openable windows, doors, natural air movement, exhaust fans, trickle vents, mechanical ventilation or more advanced systems such as heat recovery ventilation. The right approach depends on climate, building design, airtightness, outdoor air quality, occupant needs and the level of performance being pursued.
The important point is that ventilation should be deliberate. A home should not rely only on accidental gaps, cracks and draughts to provide fresh air. That approach can undermine comfort, energy performance and moisture control.
Airtightness and ventilation need to work together
Airtightness is often misunderstood. A more airtight home is not meant to be an unventilated home. Airtightness reduces uncontrolled air leakage, while ventilation provides fresh air in a controlled way.
CSIRO notes that better airtightness can support comfort, lower energy bills and healthier indoor air quality, but that as airtightness increases, controlled ventilation becomes vital to avoid condensation and mould. This balance is critical in higher performing homes. CSIRO
For Green Star Homes aligned projects, airtightness and ventilation should be considered together. A leaky home may be inefficient and uncomfortable. A very tight home without appropriate ventilation may trap moisture and pollutants. The goal is a home that is both well sealed and well ventilated.
Moisture control is part of indoor air quality
Moisture is one of the most important indoor air quality issues in Australian homes. Everyday activities such as cooking, showering, washing, drying clothes and breathing add moisture to the air. If moisture is not managed, it can contribute to condensation, dampness and mould risk.
Moisture control depends on ventilation, exhaust systems, building fabric, surface temperatures, insulation, airtightness, thermal bridging, drainage and occupant behaviour. A cold surface in a poorly insulated room can increase condensation risk. A bathroom without effective exhaust can hold moisture for too long. A kitchen without appropriate extraction can add moisture and pollutants to the home.
A healthier home should remove moisture at the source where possible and maintain indoor conditions that reduce the likelihood of dampness and mould.
Material choices can affect indoor air
The materials used inside a home can influence indoor air quality. Paints, adhesives, sealants, flooring, cabinetry, furniture, insulation, finishes and cleaning products can release pollutants into the indoor environment, especially when ventilation is poor.
A healthier home should consider low emission products, durable materials, appropriate finishes and construction practices that reduce unnecessary pollutant sources. Material selection is not only an environmental question. It is also an indoor health question.
In a Green Star Homes context, material choices sit alongside ventilation, comfort and resilience. A home can only be truly healthy when the indoor environment is considered as part of the sustainability strategy.
Gas, combustion and indoor pollutants
Combustion sources can affect indoor air quality. Gas cooking, unflued gas heaters, fireplaces, wood smoke, attached garages and outdoor smoke events can all introduce pollutants into or near the home if not managed carefully.
Green Star Homes places emphasis on fossil fuel free and renewable powered homes. From an indoor air quality perspective, all electric design can help reduce some combustion related risks inside the home, particularly when combined with good ventilation and kitchen extraction.
This does not mean equipment choice alone solves indoor air quality. A home still needs ventilation, moisture control, filtration where appropriate and careful attention to indoor pollutant sources. But reducing combustion inside the home can support a healthier residential environment.
Outdoor air quality and resilience
Indoor air quality is also affected by outdoor conditions. Bushfire smoke, traffic pollution, dust, pollen, humidity and nearby pollution sources can all influence the air entering the home.
YourHome advises that homes should be designed to allow controllable ventilation and be well sealed when required to avoid pollutants from outdoor combustion sources, such as bushfires, entering the home. This is especially relevant as climate related events and smoke exposure become more important in Australian residential design. YourHome
A resilient home should be able to provide fresh air under normal conditions and reduce unwanted pollutant entry during poor outdoor air events. This requires more thoughtful design than simply making the home leaky or relying on open windows at all times.
Common indoor air quality issues in homes
Indoor air quality problems are often connected to design, construction, products and everyday use. Common issues include:
- Insufficient ventilation in bedrooms, living areas or wet rooms.
- Poorly performing bathroom, laundry or kitchen exhaust systems.
- Moisture build up from cooking, showering or drying clothes indoors.
- Condensation on windows, walls or thermal bridges.
- Mould risk caused by dampness, cold surfaces or poor air movement.
- Pollutants from materials, finishes, furnishings or cleaning products.
- Combustion pollutants from gas cooking, heaters, fireplaces or attached garages.
- Outdoor smoke, pollen, dust or traffic pollution entering the home.
How indoor air quality relates to Green Star Homes
Green Star Homes provides a useful framework because it connects indoor air quality with the broader idea of healthier homes. It recognises that residential sustainability is not only about energy numbers. It is also about whether the home supports the people who live inside it.
Indoor air quality also connects with the positive and resilient parts of Green Star Homes. A home that is well sealed, well ventilated, fossil fuel free and designed for changing outdoor conditions is more likely to remain comfortable and healthy over time.
The strongest outcomes come when ventilation, airtightness, materials, moisture control, thermal comfort and services are considered together rather than one at a time.
How indoor air quality relates to BASIX, NatHERS and Whole of Home
Indoor air quality is not always the main focus of BASIX or NatHERS, but it is connected to many of the same design decisions. Glazing, insulation, airtightness, thermal comfort, ventilation, hot water, cooking, heating, cooling and appliance choices can all influence the indoor environment.
NatHERS helps assess the thermal performance of the home. A better thermal envelope can reduce uncomfortable cold surfaces and overheating risk. Whole of Home considers major household systems, including heating, cooling, hot water and cooking, which may influence both energy use and indoor conditions.
For NSW projects, BASIX documentation should remain consistent with the design assumptions around ventilation, services, thermal performance and energy systems. For Green Star Homes thinking, these same decisions can be part of a healthier residential strategy.
Practical considerations for project teams
For architects, builders and developers, indoor air quality should be considered early. Many of the important decisions are made before the home is built, including ventilation strategy, kitchen extraction, bathroom exhaust, material selection, airtightness and moisture detailing.
Design ventilation deliberately
Confirm how fresh air enters the home and how stale or moist air is removed. Openable windows, exhaust fans, mechanical ventilation and filtration should be considered in relation to climate, airtightness and outdoor air quality.
Manage moisture at the source
Bathrooms, laundries and kitchens need effective exhaust and moisture control. Condensation risk should be considered alongside insulation, thermal bridging, surface temperatures and ventilation.
Choose lower emission materials where possible
Paints, adhesives, sealants, flooring, cabinetry and finishes can affect indoor air quality. Lower emission products and durable material choices can support a healthier indoor environment.
Consider all electric design
All electric design can reduce combustion sources inside the home. This may support indoor air quality, especially when combined with good kitchen extraction, ventilation and efficient services.
Coordinate airtightness with ventilation
Airtightness should not be pursued without a ventilation strategy. A better sealed home needs deliberate fresh air and moisture control so that comfort, energy efficiency and indoor air quality improve together.
How Certified Energy can help
Certified Energy helps residential project teams understand how healthier home outcomes relate to BASIX, NatHERS, Whole of Home and Green Star Homes principles.
For projects exploring Green Star Homes, our team can help review how ventilation, thermal comfort, building fabric, services, glazing, insulation and all electric design decisions fit into the broader sustainability pathway. We can also help identify where indoor environmental quality may need more detailed consideration by the design team or relevant consultants.
The aim is to help project teams avoid treating healthy homes as a separate issue. Indoor air quality, comfort, energy use and resilience are connected parts of the same residential performance system.
Need healthier home performance advice?
Send your residential plans to Certified Energy and our team can help review the BASIX, NatHERS, Whole of Home and broader sustainability pathway for your home.
Get a QuoteRelated resources
- Green Star Homes Knowledge Hub
- NatHERS Knowledge Hub
- BASIX Knowledge Hub
- Whole of Home Knowledge Hub
- Passive House Knowledge Hub
- WELL Rating Knowledge Hub
- ESD Consultancy
Frequently asked questions
Why does indoor air quality matter in sustainable homes?
Indoor air quality matters because a sustainable home should support the people who live inside it. Good indoor air can improve comfort, reduce pollutant build up, manage moisture and support healthier daily living.
How does ventilation improve indoor air quality?
Ventilation brings outdoor air into the home and helps dilute and remove carbon dioxide, moisture and airborne pollutants. It can be provided through natural ventilation, exhaust systems or mechanical ventilation, depending on the design.
Is airtightness bad for indoor air quality?
Airtightness is not bad when it is paired with controlled ventilation. A better sealed home can improve comfort and energy performance, but it needs deliberate ventilation to avoid stale air, condensation and moisture issues.
Can all electric homes improve indoor air quality?
All electric homes can reduce combustion sources inside the home, which may support indoor air quality. They still need appropriate ventilation, kitchen extraction, moisture control and careful material selection.
What causes poor indoor air quality in homes?
Poor indoor air quality can be caused by inadequate ventilation, moisture build up, mould, combustion sources, material emissions, cleaning products, dust, outdoor smoke, traffic pollution and poorly performing exhaust systems.
How does indoor air quality relate to Green Star Homes?
Indoor air quality relates to the healthy homes part of Green Star Homes. It also connects with resilience, comfort and energy performance because ventilation, airtightness, materials, moisture control and services all influence how the home performs over time.
