Opinion | 3 November 2021
Professor Carolyn Hayles, Professor of Environmental and Sustainable Design for the Built Environment, Cardiff School of Art and Design.
Did you find it harder to get a good night's sleep during this summer's heatwave? Did you, like many, ditch your duvet, buy an electric or battery-operated fan, or move you, or your children/elderly parents to a cooler room to help them get a good night's sleep? If you have suffered room temperatures of 26˚C or more, your home is experiencing what is known as summertime overheating, and you are starting to feel the impacts of climate change.
When we experience a warmer than normal period during the summer, we still behave as if it's surprising; however, we have faced this summertime overheating phenomenon for many years now, with climate predictions showing this is only set to get worse. For example, let us consider the six-week period from 22 July – 31 August, which coincides with our annual school holidays. Met Office climate data sets demonstrate that right now [the 2021-2040 period], the temperature in Cardiff, will be more than 2˚C above baseline temperatures [recorded between1981-2000], and by 2070 [2061-2080], this will be 5.5˚C above baseline values. This implies that what we consider a scorcher is in fact the norm for this time of year; and summer temperatures in Cardiff, and elsewhere will continue to steadily rise. But what does this mean for our homes and how we live in them?
As an embedded climate research fellow at Welsh Government, I have spent the past year looking at how resilient buildings in the UK and Wales are to challenges associated with a changing climate. This research includes climate vulnerability modelling, in collaboration with Resilient Analytics, to understand the impacts of climate change on people's homes in Wales. We looked at the relationship between outdoor climate [temperature, sunlight, rainfall, and moisture] and indoor conditions. The results reveal increased incidences of summertime overheating in the majority Welsh homes. The best performing dwellings, i.e., those least impacted by summertime overheating, were those built before 1919 and houses with solid stone walls. The poorest performing, where occupants can expect progressively reduced levels of comfort, were houses constructed after 1990, flats and properties with internal wall insulation.
But the impact of climate change on our homes doesn't just stop at temperature and overheating. Have you noticed more mould growth, particularly in your bathroom or kitchen? Are you finding it harder to manage/eradicate it? This too may be your house telling you that you need to adapt to accommodate for the effects of climate change. The amount of moisture trapped in our homes is important because optimum moisture content [relative humidity] for human comfort and health lies between 30-60%. Anything above this can result in bacterial and fungal growth, leading to allergic rhinitis, asthma, and other respiratory infections. Our research shows, that for the same six-week period, there is the potential for poorer indoor environmental quality due to an increase in trapped moisture, which could be impacting our health. Coastal dwellings in places such as Llangefni on Anglesey or Narberth in Pembrokeshire, will experience unwelcome increases in relative humidity, regardless of housing age or construction. Relative humidity will be highest in pre 1919 dwellings and dwellings with solid stone walls regardless of location, because the relationship between temperature and relative humidity is inversely proportional; where indoor temperatures are lower, the air will be wetter and thus relative humidity will increase. This of course, does not bode well for the cooler, wetter months of October through to March.
So, what can we do to lessen the impact of climate change on our homes? Well, we need to adapt our behaviours, our interiors, and our building fabric maintenance regimes. To reduce summertime overheating we will need localised strategies which will include ensuring appropriate air circulation [ventilation], glazing, and shading devices to manage internal solar gains. We may need to change the way we organise our internal spaces, manage our internally generated thermal-gains, and if possible, improve our immediate external microclimate by painting walls a pale colour to reflect light, and planting more vegetation, to absorb both heat and pollutants. Certainly, we will also need ventilation strategies to improve the extraction of moisture-laden air, and indoor-generated pollutants, to avoid increased incidences of condensation, damp, and mould growth, and adverse impacts from other allergens, particles, and pollutants. We also need to consider our repair and maintenance regimes, which will also allow us to prepare for other climate change effects, including wetter weather, heavier downpours, and resultant flooding. For example, with increased rainfall we will need to check our downpipes and gutters more frequently and coupled with increased levels of sunlight we will need to recoat our doors, windows, and fascia boards more frequently to avoid blistering paint as well as moisture ingress.
Whilst, understandably, the focus for many homes in recent years has been on climate change mitigation, decarbonisation, improved energy efficiency, and reducing the burden of winter fuel poverty; there is now a need to consider climate change impacts more holistically. In fact, the Climate Change Commission [CCC] have acknowledged that the need for summertime cooling could lead to additional fuel poverty. It is therefore important that mitigation and adaptation are managed collectively to avoid future maladaptation.
Everyone in Wales will be affected by climate change. As Welsh citizens, we can do our bit towards achieving Wales's net zero plan, by choosing to climate-proof our homes, and how we live within them, in a way that doesn't rely on carbon-intensive solutions, but on modest behaviour change, low-tech adaptations, and, where possible, lower carbon, low energy approaches to heating, cooling, and ventilating.