Researchers blow hot and cold on the ideal temperature for office productivity

With temperatures in the UAE set to rise up to 50°C this weekend, the issue of overcooling in offices has regained focus, with research revealing its benefits.

Published earlier this month, the UAE study found that setting the air conditioner to a lower temperature improved concentration.

Researchers from institutions, including Ajman University, recorded the brain activity of 64 men, in their 20s, inside a room at two separate temperatures – 20.5°C and 24°C.

They were monitored using an electroencephalogram (EEG) over 70 minutes.

"Results showed lower temperatures [20.5°C] increased EEG frequency, indicating better attention than [at] 24°C. Statistical analysis revealed that concentration was achieved faster at lower temperatures," the researchers wrote in Architectural Science Review.

"Thus, contrary to general perception, a slightly cooler environment seems more conducive to focused attention than a conventionally comfortable one."

While there are caveats – the researchers said the sharp rise in attention at lower temperatures could indicate stress – the study appeared to indicate that what might be most comfortable is not necessarily best for concentration.

What's the ideal temperature?

There is still dispute over the ideal indoor temperature.

One study in Qatar, published this year in Building Services Engineering Research and Technology under the title "Freezing from the heat", set the ideal temperature higher than the UAE research at about 24.9°C.

"We are of the firm opinion that warmer temperatures are desirable and that they will actually result in greater productivity, not lesser," said one of the study’s authors, Prof Sukumar Natarajan from the University of Bath.

Some even expand the band to touch highs of 27°C.

Srinivasan Rangan, senior director for engineering at Taqeef, an air conditioning company in the UAE, said the ideal AC temperature for comfort is between 22°C and 27°C based on recommendations from US and European bodies.

"This moderate temperature band balances thermal comfort with energy efficiency considerations for cooling systems," he said, adding that residents can set their ACs to 24°C to allow for comfort, maximise efficiency and reduce energy costs.

"Small adjustments from 24°C can optimise different tasks: 22°C to 25°C for peak productivity when working from home and 20°C to 22°C for children’s learning."

What may be ideal for one person may be uncomfortable for another.

Alan Hedge, professor emeritus in the Human Centred Design Department at Cornell University in the US, said body size, body fat, skin colour, body hair and age also contribute to reaching the ideal temperature.

Other variables that have an influence include clothing, posture, what a person is sitting on, time spent in that environment, time of year (comfortable temperatures are lower in winter), time of day, humidity level and air speed.

"It is hard to satisfy everyone and typically standards that have been developed recommend conditions [that are] estimated to be acceptable to 80 per cent of people," Prof Hedge said.

Gender plays a key role

Research shows that gender is a key variable in determining efficiency and comfort.

Since women tend to prefer warmer temperatures, on average, they are likely to feel the effects of overcooling more.

Taqeef’s Mr Rangan cites 2019 research that indicated that for women, setting the thermostat at 26°C or more may benefit productivity.

"At higher temperatures, women perform better on a math and verbal task, while the reverse effect is observed for men," the researchers wrote in Plos One.

They said the increase in female performance at higher temperatures was "significantly larger" than the corresponding decrease in male performance, leading them to conclude that gender-mixed workplaces "may be able to increase productivity by setting the thermostat higher than current standards".

'Thermal memory is real'

Another important factor that determines temperature preference is where a person comes from.

In a UK-based research that is currently being reviewed before publication, Prof Natarajan and his colleagues paired British volunteers with Indian participants, who were in the UK for a few weeks, in a climate chamber.

"The true response between the Indian subjects, who carried a thermal memory of much warmer climates compared to the British subjects, was fundamentally different. They were much more tolerant of warmer temperatures.

"It is not earth-shattering news to anybody if I say an Indian subject is likely to be tolerant of warmer temperatures … but we were able to quantify that in a very measurable way."

Studies like this show that "thermal memory" is real and that people are adapted to a particular environment.

"If you’re somebody from the UAE who’s essentially grown up in a hot outdoor but cool indoor, your expectations might be different from somebody who’s grown up in hot outdoor but not necessarily so cool indoor," Prof Natarajan said.

"Your expectations change according to your thermal memory."

Given that temperature preferences may vary in different parts of the world, it "is probably unwise" that temperature standards developed in North America or northern Europe are applied elsewhere, suggested Prof Hedge.

Born in England, he was brought up in a house that did not need air conditioning.

"A temperature of 18 to 21°C can feel comfortable but I now live in Florida and keep my house at a ‘cool’ 27°C. Here, 18°C to 21°C would be cold to freezing."

Impact on the environment

However, builders do not factor this variation in and often use a single set of AC controls for more than one room.

"Some part of a house will not need cooling at that particular time, but you’re forced because of this one button," said Habiba Al Marashi, chairperson of the Emirates Environmental Group and a co-founder and vice chairperson of Emirates Green Building Council.

Aside from being financially wasteful, this also has an environmental impact, because much of the electricity consumed by air conditioners is expected to be generated by burning fossil fuels.

There is also a tendency to overcool buildings thus increasing carbon emissions, she added. That is because at the design stage, there is often "an overestimation" of a building’s cooling requirements.

Ms Marashi would like to see tougher regulations on air conditioning systems, including requirements that they can be easily adjusted – a move that might be welcomed by residents in the Gulf who often feel the chill indoors despite living in one of the hottest parts of the world.