Last edited 09 Dec 2020

Evolving opportunities for providing thermal comfort

This article summarises a research paper, ‘Evolving opportunities for providing thermal comfort’ by Gail Brager, Hui Zhang & Edward Arens published in 2015 in --Building Research & Information, 43:3, 274-287, DOI: 10.1080/09613218.2015.993536.

The paper proposes new ways of thinking about the design and operation of buildings to provide enhanced thermal experiences and reduce energy consumption. The strategies that are suggested are supported by research, development and monitoring of new practices carried out by the Center for the Built Environment (CBE) at the University of California, Berkeley.

It is estimated that buildings in the USA contribute 39% of total greenhouse gas emissions, with 80% of this resulting from energy use for heating, cooling, ventilation and lighting. A significant proportion of this energy use is a consequence of controlling the internal environment of buildings within a narrow range of temperatures, even though this leaves 20% of occupants dissatisfied.

The current tendency is to create uniform conditions in buildings with a temperature range of between 22 and 24°C, delivered through fully-controlled heating, ventilation and air conditioning (HVAC) systems. However, this is energy intensive and can result in thermal monotony, or thermal boredom. In addition, cooling systems frequently over-cool, delivering temperatures in the summer that are below those in the winter.

Studies have suggested that for every 1°C of expansion in either direction of the narrowly-controlled thermal ‘dead zone’, annual central HVAC energy consumption can be reduced by 10%. In addition, it is proposed that greater comfort, and even thermal pleasure, can be achieved by a more dynamic, non-uniform environment, and that a temperature range of 21 to 27°C can achieve optimal operative performance.

The paper suggests that performance is more strongly related to thermal comfort, rather than temperature per se, with influences such as; humidity, air movement, operative control and personal comfort systems, and it cites an emerging understanding of ‘alliesthesia’ which proposes that more variable indoor environments can enhance satisfaction and well-being.

The paper sets out five changes that could help deliver a richer thermal environment and reduce energy consumption:

Moving from centralised to personal control.
From still to breezy air movement.
From thermal neutrality to delight.
From active to passive design.
From disengagement to improved feedback.

To remove barriers to adopting these changes, practitioners and researchers must work together to influence building standards, design guidelines and green building rating systems.

Gail Brager, Hui Zhang & Edward Arens (2015) Evolving opportunities for providing thermal comfort, Building Research & Information, 43:3, 274-287, DOI: 10.1080/09613218.2015.993536.

Read the full paper at Taylor & Francis Online.