Finnish housing is not well suited for the changing climate
Most of Finland is experiencing several degrees warmer than average temperatures at this time of year, with several ‘hot days’ of over 25°C, and even hotter days forecast in the coming days.
Exposure to high temperatures can cause significant health risks to the population; for example, the heatwave in 2018 is thought to have led to 380 premature deaths in Finland.
Climate warming will make such heatwaves commonplace, with summer temperatures predicted to be up to 5°C higher by 2100, and summer temperatures of 35°C will occur regularly. The problem is compounded by an aging population, as those over 65 are more vulnerable to heat-related illnesses or even death.
Jonathon Taylor, lecturer in Sustainable Urban Development and affiliated member of ASUTUT, having just joined from University College London, UK, is an expert on climate change adaptation and heat exposure and health and says: “As the climate continues to warm, Finnish housing will need to adapt to hotter summers or risk significantly increasing energy consumption for cooling and health risks for occupants”.
Cold climate focused design can cause problems during summer in energy efficient homes
Finnish housing has been designed for a cold climate, with high energy efficient building envelopes and airtightness designed to keep warm air inside, whether that warmth is generated by heating devices, or by our own body heat and activities, or by the sun’s rays.
“Energy efficiency is a good thing – heating buildings during winter consumes a significant amount of energy, and is a large contributor to national greenhouse gas emissions. However, designing with a focus on a cold climate can exacerbate problems in summer, as heat become trapped inside our homes by the high levels insulation, low ventilation rates, and the lack of large openable windows to allow hot air to escape”, Taylor says.
In addition, wood constructed buildings can heat up faster during the daytime, while long hours of daylight mean that housing is exposed to longer periods of direct solar radiation through windows in the mornings and evenings. Many Finns also live in apartment buildings and single-storey bungalows, which research from the UK indicates are at greater risk of overheating than semi-detached houses or townhouses.
Covid-19 transformed homes into offices and self-isolation shelters
Finland is cautiously coming out of a pandemic induced lockdown, although a lot of people continue to work from home. This exceptional time has highlighted that our homes had to not only be spaces for rest, leisure and family time, but to also transform overnight to become simultaneously a home office, a home school, nursery, playground, exercise area, pandemic shelter and so on.
Affiliated member of the ASUTUT research group, post-doctoral researcher Raúl Castaño-Rosa says: “For many of the most vulnerable, such as the elderly or ill, the need to isolate indoors will continue, and they will be at an increased risk of exposure to high indoor temperatures.”
Energy needed for cooling might nearly equal that of heating in the future
The ASUTUT research group at Tampere University has established expertise in evaluating building overheating risk as part of their research into sustainable housing. This includes a focus on adapting housing to a changing climate while reducing energy consumption and improving sustainability.
Recent research by MSc student Heidi Sukanen found that housing in Helsinki and Jyväskylä already experiences temperatures above current exposure guidelines of 27°C, and that this is set to worsen in the future when cooling needs may increase by 40-80%. However, simple changes to housing can help to reduce overheating risk, or the need for air conditioning.
“These measures can include changing window glazing specification, external shading, and cross flow ventilation during daytime and nighttime. External shades are much more effective than internal blinds in preventing the sun’s rays entering the spaces, and should be considered in climate-proof designs for buildings”, Sukanen says.
Previous research has shown that without proper solar protection the yearly need for cooling energy can nearly equal that of heating in small studio apartments in Helsinki. Even in the much colder climate of Sodankylä, cooling can constitute a quarter of an apartment’s temperature control related energy consumption.
”Given a warming climate, housing in Finland will need to evolve to become not just energy efficient and comfortable during the winter, but during the summer as well. Future ASUTUT research will help to develop the evidence base needed to inform the necessary changes, helping to mitigate against the potential negative impacts on increased heat for health and energy consumption”, Sofie Pelsmakers, ASUTUT chair, says.
Text and photos: Jaakko Kinnunen