Wet-bulb temperature
Wet-bulb temperature (Twb, Tw or WBT) is the temperature recorded by a thermometer that has its bulb wrapped in cloth and moistened with distilled water. It can be expressed in Celsius (C), Fahrenheit (F) or Kelvin (K).
The rate of evaporation from the wet bulb, and so the temperature it records varies depending on the humidity of the air it is exposed to. The higher the humidity, the lower the rate of evaporation and so the higher the temperature recorded. Wet-bulb temperatures are the same as dry-bulb temperatures at a relative humidity of 100%, but otherwise they will be lower than dry-bulb temperatures due to the cooling effect of evaporation (described as wet-bulb depression).
Wet-bulb temperature is an indicator of the temperature felt when damp skin is exposed to the air and so can be used to express a component of thermal comfort. The wet bulb globe temperature index (WBGT) is widely used for the assessment of heat stress and combines wet-bulb temperature, dry-bulb temperature and globe temperature (mean radiant temperature).
A sling psychrometer holds both wet and dry-bulb thermometers and can be used to express the physical and thermal properties of moist air on a psychrometric chart.
[edit] Related articles on Designing Buildings
Featured articles and news
Change of use legislation breaths new life into buildings
A run down on Class MA of the General Permitted Development Order.
Solar generation in the historic environment
Success requires understanding each site in detail.
Level 6 Design, Construction and Management BSc
CIOB launches first-ever degree programme to develop the next generation of construction leaders.
Open for business as of April, with its 2026 prospectus and new pipeline of housing schemes.
The operational value of workforce health
Keeping projects moving. Incorporating unplanned absence and the importance of health, in operations.
A carbon case for indigenous slate
UK slate can offer clear embodied carbon advantages.
Costs and insolvencies mount for SMEs, despite growth
Construction sector under insolvency and wage bill pressure in part linked to National Insurance, says report.
The place for vitrified clay pipes in modern infrastructure
Why vitrified clay pipes are reclaiming their role in built projects.
Research by construction PR consultancy LMC published.
Roles and responsibilities of domestic clients
ACA Safety in Construction guide for domestic clients.
Fire door compliance in UK commercial buildings
Architect and manufacturer gives their low down.
The new towns and strategic environmental assessments
12 locations of the New Towns Taskforce reduced to 7 within the new towns draft programme and open consultation.
Buildings that changed the future of architecture. Book review.