More Than Just Comfort
Temperature and humidity are often dismissed as comfort preferences, but they have significant and measurable effects on health, air quality, and even the accuracy of your CO2 monitor. Understanding these relationships helps you create a healthier indoor environment.
Humidity and Health
The ideal indoor relative humidity range is 40-60 percent. Outside this range, problems emerge:
Too Low (Below 30%)
- Dry skin and irritated airways — mucous membranes dry out, reducing your first line of defence against viruses
- Increased virus survival — influenza and other respiratory viruses survive longer in dry air
- Static electricity — annoying and can damage electronics
- Dust suspension — dry air keeps particles airborne longer, worsening PM2.5 levels
Too High (Above 60%)
- Mould growth — mould thrives above 60% humidity and releases spores that trigger allergies and asthma
- Dust mites — peak reproduction occurs at 70-80% humidity
- VOC amplification — higher humidity increases off-gassing rates from furniture and building materials. See our VOC guide.
- Condensation — promotes water damage and microbial growth on surfaces
Temperature Effects
Indoor temperature affects air quality in several ways:
- Higher temperatures increase VOC emissions — formaldehyde off-gassing roughly doubles with every 5-degree Celsius increase
- Thermal comfort affects perception — people rate air quality lower when they feel too warm, even if pollutant levels are identical
- HVAC efficiency — extreme temperatures force HVAC systems to recirculate more air rather than bring in fresh outdoor air, potentially raising CO2 levels
Practical Recommendations
- Monitor all three metrics — CO2, temperature, and humidity together give a complete picture. Most multi-sensor monitors cover all three.
- Target 20-24 degrees Celsius and 40-60% humidity — this range optimises comfort, health, and air quality.
- Use a humidifier or dehumidifier — when natural conditions push humidity outside the ideal range.
- Ventilate strategically — balance fresh air needs with temperature and humidity control. An ERV helps manage this trade-off.
- Check your monitor placement — avoid placing monitors near heat sources that could affect readings. See our placement guide.
Use the CO2 calculator to factor room conditions into your ventilation planning.