Page 42 - Climate Control News Magazine April 2019
P. 42

Temperature Gauge
DR FAN ZHANG FROM GRIFFITH UNIVERSITY’S SCHOOL OF ENGINEERING AND BUILT ENVIRONMENT AND CITIES RESEARCH INSTITUTE EXPLAINS WHY 22°C IS NOT THE IDEAL TEMPERATURE FOR WORKER PRODUCTIVITY.
Chilly review of thermal comfort zone
Arithmetic relationships have been proposed by different researchers to quantify the produc- tivity decrement in percentage terms as room temperature (or thermal sensation) deviates from the temperature optimum.
These functions have then often been sub- jected to cost-benefit analyses that trade off the costs of lost productivity from the build- ing’s workforce against the costs of variations in building and building services design, ret- rofits, and operational facilities’ manage- ment practices.
However, temperature effects on productivity cannot be readily quantified, particularly with simulated performance tests.
For one reason, simulated performance tasks do not accurately represent the nature of real work carried out in actual workplaces. For an- other, the effects of other factors of productivity beyond environmental factors cannot be elimi- nated from the research design.
Practical implications of temperature ef- fects on performance or productivity relates to how we manage and control our buildings. The inverted-U model encourages facility managers to specify heating and cooling set- points as close together as technology per-
“PRACTICAL IMPLICATIONS OF TEMPERATURE EFFECTS ON PERFORMANCE OR PRODUCTIVITY RELATES TO HOW WE MANAGE AND CONTROL OUR BUILDINGS.”
– DR FAN ZHANG, GRIFFITH UNIVERSITY
mits; however, according to the extended-U model, indoor thermal environments can be controlled much less stringently than is cur- rently practiced.
Contrary to the inverted-U function that has incurred horrendous waste of energy, the ex- tended-U relationship has huge potentials in building energy conservation.
Therefore, facility managers and building ser- vice engineers need to recognise that indoor temperatures spanning the full range of thermal comfort zone are serviceable instead of blindly pursuing a speciously defined single-tempera- ture optimum.
–withGriffithNews ✺ ABOUT THE AUTHOR
Dr Fan Zhang of Griffith University’s School of Engineering and Built Environment.
SETTING THE TEMPERATURE at 22°C has be- come standard practice in office environments the world over and is even listed in commercial tenancy agreements in countries like Australia.
But an extensive review of research literature on the relation of moderate thermal environ- ment to cognitive performance has found the evidence does not support the view that a chilly 22°C is the optimum temperature to maintain worker productivity.
My review, which was undertaken with re- searchers from the University of Sydney and the University of Central Florida, examined two pre- vailing conceptual models pertaining to temper- ature effects on cognitive performance – the in- verted-U model and the extended-U model.
Entitled 'Effects of moderate thermal envi- ronments on cognitive performance: A multi- disciplinary review', it found there is not a sin- gle optimum temperature featured by the inverted-U model that is most ideal for cogni- tive performance.
Instead, human response efficiency follows an extend-U relationship with indoor tempera- tures, i.e., human performance remains relative- ly stable across a broad range of acceptable tem- peratures, but it rapidly deteriorates at the boundaries of thermal acceptability.
Guidebooks for heating, ventilation and air conditioning (HVAC) peak bodies such as The Federation of European Heating, Ventilation and Air Conditioning Associations (REHVA)
and The American Society of Heating, Refriger- ating, and Air-conditioning Engineers (ASHRAE) claim office performance follows an inverted-U function with indoor temperature and peaks at 22°C.
Despite being widely derided as ‘the luxuri- ous discomfort of the rich’ requiring excessive energy use, it is simplistically justified in terms of productivity gains from expensive human resources.
Since REHVA and ASHRAE exert a strong in- fluence on air conditioning practices, HVAC-re- lated energy use, and greenhouse gas emissions well beyond their European and North American jurisdictions, it behooves us to critically review the scientific evidence put forward in support of temperature effects on cognitive performance and productivity.
In our paper, we have critically reviewed nearly 300 scientific evidences from multiple research disciplines – built environment, psy- chology, physiology, ergonomics, neuroscience, sports science, medical science, learning and instructional design, and human-technology interaction – on the cognitive performance re- search theme.”
And the weight of research evidence reviewed does not favor the inverted-U function, but the extended-U relationship instead.
The team also questioned the cost-benefit analysis and so called ‘productivity loss’ due to adverse temperatures.
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