Why are people dying in the summer?
On July 19 2022, a temperature of 40.3 °C was recorded and verified by the Met Office in Coningsby, England, breaking the previous record of 38.7 °C set in Cambridge, England in 2019. On July 19 2022, there were also 638 more deaths recorded in England than usual.
This raises the following questions - why did so many excess people die? Are the buildings they occupied suitable to live in during summer? What can we do to keep our vulnerable citizens cool in the summer?
Social housing and care settings in particular have a high risk of overheating, which is of a great concern when occupied by older populations. Overheating in homes can impact the health of the elderly significantly more than younger generations. One of several reasons is they are often less mobile and more likely to spend extended periods of time indoors, which can make it difficult for them to escape the heat and can exacerbate the effects of overheating. Therefore, it is crucial that these vulnerable settings are investigated to ensure spaces occupied by elderly populations are thermally comfortable.
A recent cross-Atlantic study by researchers at University College of London investigated the indoor environmental impact on seniors in public housing during the 2017 heat waves. During heat waves, senior residents are exposed to both uncomfortable indoor temperatures and poor air quality, according to the study, which looked into the role of window openings in their overall thermal comfort.
The study considered public housing in New Jersey, USA where low-income seniors reside. The buildings were monitored to study the indoor environmental impacts during the time heat waves in 2017. Compared to the UK where mild climate is characterized by a warm summer with average daily temperatures ranging from 16℃ to 23℃, New Jersey commonly shows hotter summers between 26℃ and 32℃. Apart from air temperature, the level of humidity is also necessary when assessing thermal comfort, which is heightened in summertime New Jersey.
A heat wave was defined as more than two consecutive days with maximum temperatures above 32℃. For this assessment, the indoor temperature threshold was set at 27℃ and air pollution threshold was specified at 35 µg/m3 as average daily PM2.5 concentrations (PM2.5 refers to tiny particles or droplets in the air that are two- and one-half microns or less in width). Therefore, overheating and poor air quality was identified if measured thresholds were exceeded in the studied buildings.
Three types of buildings were used in the investigation: brick builds from the 1930s, concrete builds from the 1960s, and LEED-certified green builds from the 2010s, comprising a sum of 24 apartments. Amongst the three types of buildings, the green buildings were equipped with central air conditioning, while the other two buildings relied on natural ventilation via window openings.
Such apartment types, ages, and facilities are potential factors to bring about indoor environmental problems. However, an interesting finding emerging from the study is that both overheating and poor air quality was observed across all three building types. Although, there were a varying number of cases that measured values surpassing the temperature and air quality thresholds between the building types; the variations being 56 percent in the modern buildings, 84 percent in the 1960s builds, and 74 percent in the 1930s builds.
Observations using smoke and smoke-free households revealed trade-offs between indoor temperature and air quality where residents opening windows correlated to the exposure of excessive heat or PM2.5 concentrations. In some cases, natural ventilation through window opening allowed heat to enter from outside but enabled indoor pollutants to be released at the same time, especially in cases when air pollutants were emitted through residents’ behaviours, such as smoking or cooking. In other cases, opening windows resulted in lower indoor temperatures but higher levels of pollutants.
Such high rate of the exposure despite the presence of air conditioning in the modern buildings was strongly associated with each residents’ behaviour of window opening, such as what time of day and how long the windows are open for. The data suggests that less windows open in the daytime, especially near midday, combined with more window opening during the nighttime and is correlated with improved indoor temperature and air quality levels. In older buildings without central AC, improving thermal comfort is more dependent on the individual factors of the residence, such as the number of windows or what orientation the windows face. Although, it was also observed to be beneficial to avoid opening windows at midday, when external temperatures are at its peak, and to maximise window openings at night time.
The study concluded that combining multiple methods of passive ventilation can be a potential solution to deal with indoor environmental issues without the need of extra expenditure, which is especially required to increase the thermal comfort of seniors in public housing. Occupant behaviour, namely the time of day and in what rooms the windows are opened should be well considered.
Overall, natural ventilation via window openings is still an effective tool to improve the indoor environmental quality of homes, but there are countless places that our vulnerable people reside in that aren’t fit for purpose. Further research is required to balance the trade off between overheating and air quality in homes and reduce the over reliance on the resident behaviour of opening windows, especially if that resident is in a care home setting, sick, elderly, or simple incapable of doing so.
It is troubling that we are so reliant on people making the right decisions during heatwaves rather than having preventative and passive measures to help 'stop-heat-getting-in' and 'help-heat-getting-out'.
Shade the UK is looking for people to speak out on behalf of the vulnerable; if you have a story of your own, or about a loved one or neighbour who was affected by the July heatwave, we'd love to hear about it and investigate it.
Let’s act now and adapt our building stock!
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