Most large office buildings try to keep internal air temperatures hovering around 21.5°C in winter and 22.5°C in summer. They do it because the leases require it. But is that in the best interests of the occupants? We’re not sure. With record high temperatures all over Australia this summer we’ve been calculating a shirt-to-jacket ratio as a way to investigate the connections between tenants clothes choices, building management, comfort and energy use. We have been counting the jacket and shirt wearers twice a day, every day, in three large Sydney office buildings to find out more.

Australia's ABC Evening News ran a story about the issues, and featuring our study, on Sunday 13 February. The video will be here soon!

While temperature is often the main focus in determining whether a person experiences thermal comfort, managing comfort by air temperature alone in a building can be quite ineffective. Factors such as air velocity, humidity and radiant temperatures all come into play. As do the metabolic rate of the occupants and their clothing choices. These factors are all considered within the Adaptive Model of Thermal Comfort.

You may wish to visit the Thermal Comfort Index Calculator to test the effects of changing these parameters. If you do, you’ll find that the difference between summer and winter clothing attire matters – 2.2°C for typical office conditions, in fact. That started us thinking: if we only change the temperature setpoints in buildings by 1°C from summer to winter, but occupants change their clothing by equivalent to 2.2°C, will that make them more likely to feel cold in summer and hot in winter? Occupant complaint data suggests that’s exactly what might be happening (sounds like a topic for a future post…).

So we’re looking into it. Our first step in finding out for sure is to gather information on what people are actually wearing. That’s why this summer we’ve been calculating a shirt-to-jacket ratio twice a day, every day, in three large Sydney office buildings. Security guards count people as they’re coming through and categorise them: jacket / no jacket. The early findings are pretty obvious. People are less likely to wear a jacket to work when it’s hot. The question is what informs that decision? Yesterday’s weather? The weather forecast? The type of work a person does? You may have seen the study reported on ABC TV News (13 February), so if you found us after seeing the bulletin, have a look around, check out the datalyzer that shares detailed environmental information from over 45 building in capital cities. See about us and why are we doing this for more.

Stay tuned!

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