Thermal Comfort and Productivity

What is thermal comfort of a building ?

Thermal comfort is people don't feel any hot or cold feelings in a building. It means humidity, temperature, and air movement conditions should be nice and adequate to the activities conducted in building.

Generally thermal comfort is related with 4 parameters as below.

1.Air Temperature 

2.Relative humidity 

3.Air speed 

4.Radiant temperature.

According to the ISO 7730 "Thermal comfort is defined as that condition of mind which expresses satisfaction with the thermal environment" 

What are the Suitable thermal ranges ?

The human thermal environment cant be expressed in degrees. The personal experiences are depend on many number of criteria. In a same environment it may be changed to person to person.

The HSE (Health and safety Executive) has suggested as an environment can be said to achieve "reasonable comfort" when at least 80% of it's occupants are thermally comfortable.

Further Health and Safety Executive has previously introduced a temperature range between 13C and 30C as the suitable temperature range for thermal comfort.

Relative humidity should be between 40% - 60%.

Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD)

Predicted mean vote (PMV) is an index that used to predict the mean value of votes of a occupants' group on a seven points thermal sensation scale. The PMV index is depend on six factors such as metabolic rate, clothing insulation, air temperature, relative humidity, air velocity and mean radiant temperature.

The PPD (Predicted Percentage of Dissatisfied) index established a quantitative prediction of the number of thermally dissatisfied people.

The PMV/PPD model was developed by P.O.Fagner. using heat balance equations and empirical studies about skin temperature to define the standards of thermal comfort.

What are the importance of thermal comfort ?

In interior spaces, the thermal comfort is directly impact on productivity. The cold environment of  an office will reduce productivity by 4% and a warm office environment will reduce productivity by 6%.All the people like work in a comfortable environment and it will be helped to good mood of people. Increasing of productivity is target of any organization.