Lesson 7 – Indoor Environment Quality in Natural Building

Why is good Indoor Environment Quality so important?

Westerners spend on average 90 percent of their time indoors. And with indoor environments having a direct impact on our wellbeing and our health, it is important to ensure a good indoor environment quality in both our homes and offices.

In fact, its estimated that the cost of poor internal air quality in Australia may be as high as $12 billion per year due to mental and physical ill-health and lost production.

Those most at risk are people with weak immune systems, including children and the elderly.

While most will only ever experience medium health effects such as headaches or tiredness, others may suffer more serious health effects due to “sick” buildings.

On the other hand, studies also show that an enhanced indoor environment quality in offices can be linked to staff’s improved work performance and reduced sick leave.

Experience shows that good indoor environment quality has become an important criteria for not only those who are developing their own homes but also for savvy developers, who understand today’s market demands.


What Defines Indoor Environment Quality?


The quality of an indoor environment (e.g. a room) is commonly defined through the following main factors:

• Light – does the room receive enough daylight throughout the day and is comfortable artificial lighting provided for all other times?

• External views – does the room allow for distant views that provide a connection to the external environment?

Air Quality – does indoor air contain sufficient levels of oxygen and acceptable levels of pollutants from internal or external sources?

Ventilation – can the room be sufficiently ventilated (preferably naturally but where this is impractical, mechanically) and provide occupants with quality fresh air?

Thermal Comfort – is the room sufficiently insulated, shaded and conditioned to ensure comfortable temperatures throughout the year?

Noise – is the room sufficiently insulated from external noise sources and does it minimise internal reverberation and noise levels?

Occupant Control – are occupants able to control their environment, e.g. through the opening and closing of windows and blinds and operating heating and cooling services?

Materials – do the chosen building materials and finishes have low levels of Volatile Organic Compounds (VOC) and other hazardous components?

If you were able to answer all questions with ‘yes’, the room that you were referring to provides high indoor environment qualities.


Design Criteria for Improved Indoor Environment Quality

Carefully consider all aspects of good indoor environment quality during a project’s early design stage.

Experience shows that early design decisions make the greatest impact on future occupant’s wellbeing and only expensive technologies and product choices can recoup early mistakes.

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Whether via natural or mechanical means, its recommended to substantially exceeding minimum requirements for window opening sizes and air exchange rates under the Building Code.

In homes, the most effective ventilation is achieved through natural cross ventilation.

The ideal layout features openable windows located in opposite walls, which creates a breeze path to let in fresh air and flush out stale air.

Note that cross ventilation can be achieved through various façade openings, be it standard windows, operable skylights or even small solid doors.

In office buildings, air change effectiveness is important to ensure good quality air.

Carbon dioxide levels should be regularly controlled to ensure a healthy and productive work environment.

In smaller offices, natural ventilation is also a great way to save energy and cater for individual’s differing comfort needs.

Thermal Comfort

Thermal comfort describes the temperature and humidity range in which humans feel comfortable.

This range can fluctuate by many degrees and percentages, depending on activity levels, clothing, annual seasons and personal preferences.

Environmentally sustainable buildings provide thermal comfort levels with little reliance on mechanical heating and cooling systems.

This is commonly achieved through sensible orientation, good insulation, effective ventilation and flexible external shading.

In order to respond to changing weather conditions throughout the year and different user patterns, occupants should be provided with sensible controls of both active and passive systems to ensure good thermal comfort.


Product Choice

Many materials used in the fit-out and construction of homes and commercial buildings contain Volatile Organic Compounds (VOC) which pose serious health risks to building occupants.


VOC’s are found in many common construction materials however alternative low / no VOC products are available on the market including:

  • Paints;
  • Coatings;
  • Sealants;
  • Carpets;
  • Pressed wood products (e.g. cabinetry and furniture).

Commitment to low / no VOC construction materials in your home.

External Views

The provision of long distance views and a visual connection to the outdoors commonly increases wellbeing for building occupants.

In office buildings, views can reduce eyestrain for computer workers; in residential buildings views provide a sense of connectivity.

Due to statutory planning provisions, the balance between sufficient external views and limiting the overlooking into neighbouring properties needs to be carefully considered.

Internal Noise Levels

Excessive noise generated by neighbours, traffic and hard surfaces that reflect internal sounds (echo) can impact occupant’s amenity and employee’s productivity.

In order to ensure comfortable noise levels, its recommended to consider the inclusion of acoustic insulation to internal and external walls, doubleglazing to windows, landscaping that buffers traffic noise and a good balance of internal hard and soft finishes.


In order to achieve high quality daylight levels, its recommended to substantially exceeding minimum requirements for daylight under the Building Code.

Good access to natural light is essential to occupant wellbeing and employee performance. Daylight is vital for body functions, gives us a sense of time and place and connects us to our environment.

Therefore, habitable rooms with ‘borrowed light’ should be avoided. Daylight is the combination of direct and indirect (reflected) sunlight.

Therefore, on an overcast day, south facing windows will receive just as much daylight as north facing windows.

High level windows will throw daylight deep into rooms, that’s why they are particularly useful for deep floor plans.

It is also worth noting that the provision of daylight in living and working spaces reduces energy consumption.

This is due to a reduction in the use of air-conditioning, associated with the heat generated by artificial lighting.

However, in office environments, daylight has to be carefully balanced with possible glare as this strains our eyes.

Balancing Indoor Environment Qualities

Designing for a high indoor environment quality can be challenging as all criteria need to be addressed while some may even contradict each other.

Windows in particular need to be carefully designed – they influence access to daylight and ventilation, create heat gains in summer and losses in winter and provide a visual and acoustic connection to our immediate environment.

Another example is the choice of internal finishes. They not only impact on internal sound quality but also influence a room’s thermal comfort, light reflectivity and air quality.

It is therefore important to understand and carefully balance individual design and product choices upon the benefits and disadvantage for different indoor environment quality criteria.

If in doubt, we recommend talking to a sustainability expert and focusing on a project’s key indoor environment quality goals.

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