- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 21 Nov 2018
Mean radiant temperature
All bodies exchange thermal radiation with their surroundings, depending on the difference in their surface temperatures and their emissivity. This radiant exchange is an important component of the thermal comfort that will be experienced by a person, particularly in places where there may be significant differences in radiant and air temperatures, for example, near a large window.
Other factors that influence thermal comfort include: environmental factors, such as air temperature, air velocity, relative humidity and the uniformity of conditions, as well as personal factors such as clothing, metabolic heat, acclimatisation, state of health, expectations, and even access to food and drink.
Mean radiant temperature (MRT) is a measure of the average temperature of the surfaces that surround a particular point, with which it will exchange thermal radiation. If the point is exposed to the outside, this may include the sky temperature and solar radiation.
The knowledge of surface geometries required to predict mean radiant temperature is very complex, particularly in elaborate spaces. However, mean radiant temperatures can be calculated by some proprietary software applications.
Note: This equation provides a very simplified rule of thumb. There are many different variations of this equation as it is dependent complex factors such as the size and emissivity of the globe thermometer. This particular example is taken from the Novalynx Corporation 2010, however, the units used in their equation appear to be incorrect, showing air velocity in cm/s rather than m/s. Thanks for pointing this out go to Dr Robert McLeod, Senior Lecturer Built Environment - Building Services Engineering, School of Environment and Technology at the University of Brighton.
 Related articles on Designing Buildings Wiki
Featured articles and news
Modern slavery in the construction sector.
What to bear in mind when claiming damages in construction.
How do we achieve sustainable clean-water infrastructure for all?
What you should know when appointing an architect.
A brief history plus some new developments.
How computational fluid dynamics (CFD) helps building design.
The Hong Kong Harbour Area Treatment Scheme (HATS).
'Expressions of interest' for construction contracts.
Dame Judith Hackitt confirmed as keynote speaker – one year on from the Hackitt Report. Save £100 on tickets.