Determination of PMV and PPD and specification of the conditions for thermal comfort

A method for predicting the thermal sensation and the degree of discomfort (thermal dissatisfaction) of people exposed to moderate thermal environments accordign to ISO 7730. Specifications for acceptable and comfortable thermal environmental conditions.

Recommended thermal comfort requirements

Recommended thermal comfort requirements for spaces for human occupancy. It is recommended as acceptable that the PPD be lower than 10%. This corresponds to the following PMV criteria:

-0.5 < PMV < +0.5

Light, mainly sedentary, activity during winter conditions (heating period)

The conditions are the following:

  1. The operative temperature shall be between 20 °C and 24 °C.
  2. The vertical air temperature difference between 0.1 m and 1.1 m above the floor (i.e. ankle and head level) shall be less than 3 °C.
  3. The surface temperature of the floor shall normally be between 19 °C and 26 °C, but floor heating systems may be designed for 29 °C.
  4. The mean air velocity shall be less than specified in the figure below.
  5. The radiant temperature asymmetry from windows or other cold vertical surfaces shall be less than 10 °C (relative to a small vertical plane 0.6 m above the floor.
  6. The radiant temperature asymmetry from a warm ceiling shall be less than 5 °C (relative to a small horizontal plane 0.6 m above the floor).
  7. The relative humidity shall be between 30 % and 70 %.

Light, mainly sedentary, activity during summer conditions (cooling period)

The conditions are the following:

  1. The operative temperature shall be between 23 °C and 26 °C.
  2. The vertical air temperature difference between 0.1 m and 1.1 m above the floor (i.e. ankle and head level) shall be less than 3 °C.
  3. The mean air velocity shall be less than specified in the figure below.
  4. The relative humidity shall be between 30 % and 70 %.

PMV and PPD calculator

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