What Should Indoor Humidity Be With Air Conditioning On?
- Brett Wells
- Mar 15
- 3 min read
When most people turn on their air conditioner, they think about temperature. But there’s another factor that has an even bigger impact on comfort inside your home: humidity.
Humidity refers to the amount of moisture in the air. When humidity levels are too high, your home can feel sticky, heavy and uncomfortable, even if the temperature is cool.
This is especially common in coastal areas like the Gold Coast where warm ocean air carries large amounts of moisture into homes.
Understanding the correct humidity level while running your air conditioner is one of the best ways to improve comfort, reduce mould risk and protect your property.
The Ideal Indoor Humidity Level
According to international HVAC standards from ASHRAE, the ideal indoor humidity range is between 30% and 50%.
For most homes in Australia, the sweet spot is:
40% – 50% humidity
This range provides the best balance between comfort, health and energy efficiency.
When humidity stays within this range:
✔ Your home feels cooler
✔ Your air conditioner runs more efficiently
✔ Mould growth is less likely
✔ Air quality improves
Even a small change in humidity can dramatically affect how comfortable your home feels.
Why High Humidity Makes Your Home Feel Hotter
Humidity directly affects how your body regulates temperature.
When humidity levels rise, sweat cannot evaporate properly from your skin. This prevents your body from cooling itself naturally.
That’s why 25°C with high humidity can feel far hotter than 28°C with dry air.
In humid environments, homeowners often make the mistake of lowering the temperature setting on their air conditioner. Unfortunately, this can increase energy bills without solving the actual problem.
The real issue is excess moisture in the air.
Signs Your Home Has Too Much Humidity
Many homes have humidity issues without homeowners realising it.
Common signs include:
• Sticky or clammy indoor air
• Condensation on windows
• Musty smells in bedrooms or wardrobes
• Mould spots on ceilings or walls
• Damp laundry that takes days to dry
• Allergy or asthma symptoms worsening indoors
If you notice these signs, your humidity level is likely above 60%.
Why High Humidity Is Bad For Your Home
High humidity doesn’t just affect comfort. Over time it can cause serious damage to your home.
Health Risks
Excess moisture encourages the growth of:
• mould• mildew
• dust mites
• bacteria
These are common triggers for allergies, asthma and respiratory irritation.
Property Damage
Moisture also affects building materials.
Over time, high humidity can cause:
• peeling paint
• warped timber floors
• swollen doors and cabinets
• rust on fixtures
• mould growth in ceilings and walls
Coastal homes are particularly vulnerable to these problems.
How Air Conditioners Reduce Humidity
Many people don’t realise that air conditioners are also dehumidifiers.
When warm air passes over the cold evaporator coil inside your AC unit:
Moisture condenses into water droplets
The water drains away through the system
Dry air circulates back into your home
This process naturally lowers indoor humidity levels while cooling the room.
However, if your system is dirty, poorly sized or incorrectly installed, it may not remove moisture effectively.
Best AC Settings For Humidity Control
To keep humidity levels comfortable, try these simple settings:
Use “Cool Mode” Most Of The Time
Set your thermostat to 24–26°C. This allows the system to remove moisture without overcooling the room.
Use “Dry Mode” During Very Humid Days
Most modern systems include a dry mode designed specifically to remove humidity.
Avoid Setting The Temperature Too Low
Setting the AC too cold can cause short cycling, which prevents the unit from removing enough moisture.
Ensure Good Airflow
Keep vents clear and clean filters regularly so your system can circulate air properly.
Should You Use A Hygrometer?
Yes.
A hygrometer is a small device that measures indoor humidity levels.
They are inexpensive and allow you to see exactly when humidity rises above healthy levels.
Many modern smart thermostats now include humidity monitoring as well.
When To Call An Air Conditioning Professional
If your home still feels damp or sticky while the air conditioner is running, it could indicate:
• blocked condensate drains
• dirty evaporator coils
• incorrect system sizing
• poor airflow
• outdated equipment
A professional inspection can quickly identify the problem and restore proper humidity control.
Final Thoughts?
Humidity plays a huge role in how comfortable your home feels.
The ideal indoor humidity range is 30% to 50%, with 40–50% being perfect for most homes.
Maintaining this balance will:
✔ Improve comfort
✔ Reduce mould risk
✔ Protect your home
✔ Lower energy costs
If your home still feels humid even with the AC running, it may be time for a professional inspection.
📞 Questions? Call now: 0414753300
📍 Servicing: ALL Gold Coast and surroundings
