Published on April 19, 2020

AHMEDABAD: As the maximum temperature this summer has already breached 41 degrees celsius in Ahmedabad, and with the lockdown extended to May 3, it is difficult for many Amdavadis to sweat it out without airconditioners.

Many homes and some corporate offices have cut down on air-conditioning (ACs) following health advisories related to Covid-19 as a means to arrest its spread.

However, the Indian Society of Heating, Refrigerating & Air Conditioning Engineers (ISHRAE), a body of practitioners, engineers, academicians and service providers, says that one can run ACs, but with certain conditions to remain healthy and safe.

Dr Yash Shukla, technical director at Centre for Advanced Research in Building Science and Energy (CARBSE) of Cept University is part of the task force at ISHRAE that prepared a document ‘COVID-19 Guidance Document for Air Conditioning and Ventilation’, which was released earlier this week.

ISHRAE officials said the document was prepared after considering various studies relating to ventilation, indoor air quality, medical advice and the climate of the Indian sub-continent.

“The document covers a vast array of equipment ranging from AC used at home to larger air filtration systems in commercial settings and also for hospitals and isolation areas,” said Shukla.

He said that the first point is maintaining the right temperature and humidity. “Based on factors related to health and maintenance of the unit, the optimal range is 24 to 30°C. Along with that, one has to maintain relative humidity between 40% and 70%,” he said, adding that higher humidity leads to higher levels of dust mites and fungi, which could affect those with allergic conditions.

Another factor is ensuring better filtration – cleaning air filters regularly and using high-efficiency particulate arrester/absorbing (HEPA) filters – in more sensitive settings such as hospitals and patient areas. “While the filters don’t stop the Covid-19 virus itself, the virus often attaches to larger particulates which could be caught by these filters,” he said.

The third suggestion is to dilute the air and allowing as much fresh air into the premises as possible by ensuring proper ventilation. Experts said that negative pressure could be created through exhaust fans so that circulation of the same air in a closed space can be prevented.

“Recirculation of cool air by room air conditioners must be accompanied by outdoor air intake through slightly open windows and exhaust by natural exfiltration,” the document states.

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