Why it matters
Temperature and relative humidity are comfort parameters, but they also govern mould growth, dust mite populations, VOC release rates and how the human airway responds to every other pollutant.
Dubai’s summer combines extreme outdoor heat with coastal humidity, so a building that loses cooling for a few hours can reach mould-supporting conditions the same day. Over-cooling creates the opposite problem: chilled surfaces below the dew point produce condensation inside wall cavities, above ceilings and on chilled-water pipework, where nobody sees it until the ceiling tile stains.
World standards
ASHRAE Standard 55 defines thermal comfort zones for temperature, humidity and air movement. ASHRAE 62.1 addresses humidity control as part of acceptable indoor air quality.
Reference: ASHRAE Standard 55, Thermal Environmental Conditions for Human Occupancy.
UAE standards
- Dry bulb temperature: 22.5 to 25.5 °C
- Relative humidity: 20 to 60%, never exceeding 56% RH at 27 °C
- Air movement: 0.2 to 0.3 m/s
- Required for 95% of the year, in both new and existing buildings
DM separately advises keeping relative humidity below 60%, and below 50% where feasible, specifically to suppress mould and dust mites.
Reference: DM-HSD-GU119-IAQ Version 3 (2024), Table 3 and Appendix 1.
Impact on health
Humidity above 60% supports mould, dust mites and bacterial growth, and is associated with asthma, allergic rhinitis and hypersensitivity pneumonitis. Humidity below 20% dries mucous membranes, increases susceptibility to respiratory infection and causes the eye irritation frequently reported by contact lens wearers in over-cooled offices.
How to control it
- Do not fight humidity by lowering the thermostat. Dropping the set point cools the air without removing moisture and usually makes condensation worse
- Have cooling coils and condensate drainage checked. DM requires coils and condensate pipes cleaned at least every six months, and drain trays at least monthly
- Maintain positive building pressure so humid outdoor air is not drawn in through door seals, lift shafts and service risers
- Insulate chilled-water pipework and cold surfaces properly. Sweating pipes above a ceiling are one of the most common hidden mould sources in Dubai towers
- Clean any liquid spill on carpet or porous material within 24 hours, or discard it. DM treats 24 hours as the point past which the material should be removed
- Have the system checked and rebalanced for airflow, temperature and humidity after the first year and at least annually thereafter
Need this equipment serviced?
Inspection first, fixed written price before any work begins, and a photo report on completion.