Estimate operative temperature at average air speeds below 0.2 m/s, or solve for air or mean radiant temperature in degrees Celsius.

Low-air-speed approximation: assumes average air speed below 0.2 m/s.

Use occupant-relevant mean radiant temperature, rather than a single surface temperature.

Related Calculators

Operative Temperature Formula

The following equal-weight equation approximates operative temperature at average air speeds below 0.2 m/s. At higher air speeds, convective and radiative weighting must be considered.

OT = (AT + MRT) / 2
  • Where OT is the operative temperature (°C)
  • AT is the air temperature (°C)
  • MRT is the mean radiant temperature (°C)

To calculate the operative temperature, add the air temperature and mean radiant temperature then divide by 2.

What is Operative Temperature?

Definition:

Operative temperature typically refers to a single temperature value that accounts for both the air temperature and the mean radiant temperature, providing a better indication of overall thermal comfort in an environment.

How to Calculate Operative Temperature?

Example Problem:

The following example outlines the steps and information needed to calculate the Operative Temperature.

First, determine the air temperature. In this example, it is 22°C.

Next, determine the mean radiant temperature. In this example, it is 26°C.

Finally, calculate the operative temperature using the formula above:

OT = (AT + MRT) / 2

OT = (22 + 26) / 2

OT = 48 / 2

OT = 24°C

FAQ

What factors can influence operative temperature?

Operative temperature combines average air temperature and mean radiant temperature. Airflow changes their relative weighting. Humidity affects thermal comfort and evaporative cooling but is not an input to this operative-temperature formula.

Why is operative temperature important in assessing thermal comfort?

It provides a more comprehensive measure of thermal comfort by combining air and radiant temperatures, which helps in understanding how occupants actually experience an environment.

How can I adjust my environment to achieve a desired operative temperature?

By controlling the air temperature with HVAC systems and modifying the thermal properties of surfaces through insulation, lighting, or window treatments, you can better manage the overall operative temperature for improved comfort.