Adaptive Thermal Comfort & Recommended Indoor Operative Temperatures

Adaptive Thermal Comfort:

The human body has an inherent ability to adapt to the changes in environmental conditions and becomes accustomed to them over time. For example, it is important to note that people staying and working in non-air-conditioned spaces with relatively higher temperature ranges experiences very little discomfort. This presents us with an excellent logic for applying adaptive thermal comfort models for buildings. Adaptive comfort models offer an opportunity to reduce energy use as buildings can be operated at more moderate temperatures. Energy used to maintain stringent comfort conditions through mechanical equipment can thus be avoided.

For any efficient mechanical air conditioning system operating with the vapor compression cycle, the amount of energy consumption will be around 60kW per 100 TR exclusive of water distribution systems and air distribution systems. Apart from that air conditioning even will have a potential impact on global warming. Hence adaptive thermal comfort could be the best energy-conservation measure at this hour.

Operative temperatures for the model can be calculated using the formulae below

Naturally Ventilated Buildings:

Indoor Operative Temperature = (0.54 x outdoor temperature) + 12.83 

Where, indoor operative temperature (°C) is neutral temperature, & outdoor temperature is the 30-day outdoor running mean air temperature (°C). 

The 90 % acceptability range for the India specific adaptive models for naturally ventilated buildings is

 ± 2.38°C. 

For example, Indoor Operative Temperature for a naturally ventilated building in Delhi 

= (0.54 x 33.0) + 12.83 = 30.68 °C

Mixed Mode Buildings:

Indoor Operative Temperature = (0.28 x outdoor temperature) + 17.87 

Where indoor operative temperature (°C) is neutral temperature & outdoor temperature is the 30- day outdoor running mean air temperature (°C). 

The 90% acceptability range for the India specific adaptive models for mixed-mode buildings is ± 3.46°C.

For example, Indoor Operative Temperature for a mixed mode building in Delhi

 = (0.28 x 33.0) + 17.87 = 27.1 °C

Air Conditioned Buildings:

Indoor Operative Temperature = (0.078 x outdoor temperature) + 23.25 

Where indoor operative temperature (°C) is neutral temperature & outdoor temperature is the 30- day outdoor running mean air temperature (°C). 

The 90% acceptability range for the adaptive models for conditioned buildings is ±1.5°C. 

For example, Indoor Operative Temperature for an air-conditioned building in Delhi 

= (0.078 x 33.0) + 23.25 = 25.8 °C

Source: ECBC Building Code 2017