ROUNDTABLE | COMFORT STANDARDS In a warming climate, what can be done to maintain thermal comfort and productivity levels in buildings without resorting to excessive cooling? Phil Lattimore reports from a CIBSE Health and Wellbeing Group video debate The comfort zone C omfort standards in a climate-changing world was the theme of a recent roundtable hosted by the CIBSE Health and Wellbeing Group. The debate discussed the implications of a changing climate for thermal comfort in a range of building types. Introducing the debate, Ashley Bateson FCIBSE, chair of the CIBSE Health and Wellbeing Group, outlined how climate change will have implications for health and wellbeing in the UK. We are expecting hotter, drier summers and wetter winters, and this could detrimentally impact workplace productivity and comfort in schools and homes, he said. Bateson explained that, in some circumstances, overheating is already a serious problem,and cited the example of some recently completed student residences that experienced internal temperatures above 30C, partly because window openings were inadequate. He said much can be done to mitigate discomfort with an appropriate review of the design. According to CIBSE1, six factors directly affect thermal comfort: a persons metabolic rate and clothing level, and the air temperature, mean radiant temperature, air speed, and humidity of the space. The perception of thermal comfort may vary greatly between individuals depending on personal and environmental factors. The participants discussed a variety of adaptation and coping strategies, such as more casual dress codes in offices and flexible homeworking. They also spoke of dispersed working practices within offices, which allow workers to occupy spaces that suit their thermal comfort needs. Adaptive thermal comfort was discussed as a way of reducing the use of additional cooling as temperatures rise. This is where comfort temperatures gradually rise with the increase of external air temperature, so occupants become comfortable with higher temperatures after an extended period of warm weather, having the flexibility to adjust their clothing and their surrounding environment. Rather than be fixed all year round, temperature setpoints could be adjusted as outdoor temperatures change. Generally, occupants are more tolerant, and have a greater sense of adaptation, if they are in naturally ventilated buildings or in mechanically ventilated buildings with openable windows. Our offices in Doha and Melbourne wont switch the air conditioning on until it reaches 30C, says Alan Fogarty, sustainability partner at Cundall. As the weather gets warmer, people are willing to adapt. For occupiers to accept higher temperatures in offices, they need to understand the HVAC, says Derwent Londons Olivia Allen. In my experience, education around how these systems work is important. Henry Pelly, senior sustainability consultant at Max Fordham, said that having some control over decisions, such as using natural ventilation solutions, affected perceptions of comfort. Psychologically, if you have a sense of control and ownership over building decisions, there is likely to be more tolerance for feeling less physically comfortable, he says. Anna Mavrogianni, associate professor in sustainable building and urban design at Bartlett School, UCL, highlighted research on how acclimatisation levels vary for different populations. Susan May, head of housing design at Urban Design London, pointed out that, for many people outside of the office sector, adapting to the warming of climate change by using air conditioning is not an option. We need to be thinking about occupants who dont have a choice about their comfort conditions how, then, can we make all our building types work? (See panel, Covid-19 and homeworking). Fogarty said air movement was an undervalued, flexible way of improving comfort: The old way of dealing with overheating was by using ceiling fans. These are very, very effective and you can have different levels of air movement around the office with the same air temperature. You can provide different levels of perceived comfort for different people, and you get a far wider range of comfort levels in the office without throwing loads of energy at it. CIBSE says that the cooling effect of air movement created by local fans can be equivalent to reducing the operative temperature by around 2C.1 28 June 2020 www.cibsejournal.com CIBSE June 2020 p28-29 Supp Health wellbeing.indd 28 22/05/2020 17:37