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IIT-Delhi Finds City’s Comfort Zone


NEW DELHI:
Extreme summers and winters in Delhi are clearly uncomfortable. But Indian Institute of Technology (IIT) Delhi has calculated the percentage of hours when most Delhites may be finding the weather to be "comfortable". In a recent study, IIT's Centre for Atmospheric Sciences (CAS) has ranked five cities on the basis of "comfortable hours". Hyderabad has the highest comfortable hours, followed by Kolkata, Chennai, Delhi and Mumbai in the descending order.

 

The idea of which temperature range is comfortable is based on a comfort index defined by Saskatchewan weather station in Canada that considers 15 to 25 degrees comfortable while 25 to 32 degrees warm. The index, according to IIT scientists, is suited for Indian cities too. Comfort index means hours that fall under temperature, humidity and wind speed conditions that is optimum for people to carry out light to moderate physical activities without being affected by the weather. The CAS team assessed temperature and other weather data for the five cities from 2004 to 2008 and then graded them under five categories - cool, comfortable, warm, uncomfortably hot and severe danger.

 

The analysis found that 70% of the time all the five cities were uncomfortable. For instance, Hyderabad — which ranks highest as per the comfort index — had only 28.9% of the time in the comfortable category but 18.6% of the time in the uncomfortably hot category. Delhi had a whopping 12.9% of time in the severe danger category and about 26.3% of time in the comfortable category. Mumbai surprisingly has only 0.3% of the time in the severe danger category. It concludes that less than 30% of the time in these cities is comfortable for outdoor activities or indoor time without cooling needs.

 

"There is too much seasonal variation. The ranking of cities according to comfortable hours does not imply which city is most comfortable. The idea was to analyze how much time annually can be spent without the use of energy for heating or cooling. Also from the tourism point of view, we wanted to see which is the ideal time to visit these cities," said Manju Mohan, the lead author of the study. Another part of the study is to develop a method of assessing comfortable hours despite the seasonal variation. That looks at each month to check for the time that is not extremely hot or cold. For instance, "uncomfortable hours" have not been factored in the current ranking. If the ranking is done as per uncomfortable hours then Kolkata, Delhi and Chennai will rank higher than Mumbai.

Posted on 12 Apr 2012