How to calculate Indoor Operative Temperature as per ECBC?

Human body has the ability to adapt to environmental conditions and become accustomed to them over time. People accustomed to the variability of environmental parameters in non-air-conditioned buildings can live and work through a larger temperature range without experiencing thermal discomfort. This logic informs the adaptive thermal comfort model 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. 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 degree Celsius

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 degree Celsius

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 degree Celsius