Experts suggest AC temp levels amid virus rumours

With the temperatures rising, the use of air conditioners (ACs) is on the rise. Amid messages on social media about how ACs are spreading the virus in a closed environment, the Indian Society of Heating, Refrigerating and Air Conditioning Engineers (ISHRAE) has put out a ready reckoner for using cooling units at home.

“Comfort temperature is generally considered between 24º and 30º Celsius, after accounting for air velocity, relative humidity and clothing. The study of the transmission of Covid-19 virus in 100 cities of China indicates that high temperature and high humidity significantly reduce the transmission of influenza,” the report says.

For those living in areas like Hyderabad, where the relative humidity ranges between 20 and 40 per cent during the summer, it said: “Recirculation of cool air by room air conditioners, must be accompanied by outdoor air intake through slightly open windows and exhaust by natural exfiltration. Fresh air intake through a fan filter unit will prevent outdoor dust entry (containing high levels of PM 10 and PM2.5 particles) and exhaust through kitchen and toilet exhaust fans kept operational.”

It recommends room temperature setting at between 24ºC and 30º Celsius and relative humidity between 40 and

70 per cent. In humid climates, set temperature closer to 24°C for dehumidification and in dry climates closer to or at

30°C and use fans to increase air movement, it says. How to cool a room

A relative humidity level of 40%~70% is considered to be the most suitable environment for humans and decreases problems from pathogens. In dry climates, do not allow relative humidity to fall below

40%. Water evaporating from a pan kept in the room will increase humidity if it falls below 40%.

Fans should be operated with windows kept partly open. If an exhaust fan is located at a nearby location then it must be kept running to exhaust air for better ventilation.