Retrofitting Europe's homes for a hotter climate
Most of Europe's homes were built for a different climate. Rebuilding them is not an option, so as summers get hotter, Raimondo Salandra, Business Line Leader for Home Solutions at ABB Electrification’s Smart Buildings Division, looks at what can be changed: the way a home responds to the heat.
For decades, improving Europe's homes largely meant one thing: reducing heat loss.
Insulation, better glazing, airtightness and heat pumps have made homes far more efficient in winter, which is very important, but Europe's climate has changed, and homes now must deal with hotter summers as well as colder winters.
Europe has warmed at more than twice the global average over the past 30 years[1]. Homes designed around the climate of previous decades are increasingly struggling with periods of extreme heat.
Insulation helps in summer too. If a home is well insulated and properly shaded, heat takes longer to get inside. But once the heat is there, the same building fabric can make it harder to get rid of. Heat enters through windows, but it also comes from cooking, appliances and the people inside.
Even highly energy-efficient homes can still overheat.
Better insulation still matters, but in summer, comfort also depends on how the home is managed: when blinds close, when windows open and which rooms are cooled. Homes need to be able to adapt for comfort in both winter and summer.
Air conditioning isn't enough on its own
Only around 20 percent of European homes currently have air conditioning, according to the International Energy Agency,[2] compared with around 90 percent in the United States. But that is changing quickly.[3]
Nearly half of Italian homes now have air conditioning, while Britain remains at around 4.3 percent.[4] Space cooling is also one of the fastest-growing sources of energy demand in buildings.
More homes will need cooling as the climate changes. But simply adding more cooling capacity is not a complete answer.
At the same time as demand for cooling is rising, air conditioning itself is changing. Under the revised EU F-gas Regulation, the quota for placing HFCs on the EU market is being progressively reduced, with a phase-out scheduled for 2050.
All of this puts greater emphasis on how efficiently cooling is used. There is little sense in cooling an entire floor because one bedroom is occupied. Room-by-room control can make a difference.
And for many homes, major building work simply is not realistic. Around half of Europe's housing stock predates 1980. In an occupied home, changing the building fabric can be expensive and disruptive. In other cases, heritage restrictions or tenure make deep renovation difficult.
The reality is that you can't always change the building. But you can change how you run it.
What running a home for summer looks like
There are simple ways to make a home cope better with heat without changing its structure. Take shading. Most people close the blinds or shutters when they start to feel warm. By then, much of the heat has already made its way into the room.
Automation makes it possible to act earlier. Connected to weather data and the position of the sun, external shading can close before direct sunlight reaches a room and reopen when that elevation moves into shadow.
The blinds aren’t doing anything new, they’re just moving at the right time. Night-time ventilation is another good option.
The coolest part of the day often arrives when people are asleep. Leaving this entirely to the occupants is not always practical. Automated windows or vents can open when the outside air is cooler than the air inside and close again before temperatures rise in the morning. The aim is simple: get the heat out of the building overnight so it starts the next day cooler.
Then there is the cooling itself. It doesn't always need to cover the whole home. Presence detection and room-level temperature settings can allow cooling to follow the people in the home.
Research suggests that combining these measures can have a significant effect. A study in Building and Environment by Kuczyński and colleagues[5] measured test buildings through two real heatwaves, with daily maximums averaging above 30°C. Night ventilation alone lowered peak night-time temperatures in a lightweight room by 5.9K. Combined with closed external blinds and heavier construction, hours above 28°C were eliminated entirely.
This was a test room, not an occupied home, and thermal mass played a part in the result. But it shows that how you run a building can make a big difference to its indoor temperature.
Much of this can also be added to equipment that already exists.
Motorized shutters do not necessarily need to be replaced. They can be brought into a control system with actuators. Existing cooling can be scheduled and controlled by room.
In Selargius, Sardinia, a district originally built in the 1970s has become the island's first digital condominium. ABB smart building solutions control the common areas, with a KNX weather station providing live climate data to the system. Nobody rebuilt the building; they just changed how it was run.
What changes for the trade
A retrofit designed for today's climate needs to consider more than heat loss. Which rooms overheat? What happens in the afternoon? Which windows receive the most direct sun? When is the home occupied?
These questions should influence the controls strategy as much as the equipment list.
Shading and ventilation are good examples. Their value depends on when they operate. A blind that closes too late will not prevent overheating. An upstairs window that opens at the wrong time may bring more heat into the building.
Commissioning matters too. The system needs to account for seasonal changes, wind and rain protection, and what happens when an occupant overrides the automation.
And communication with the homeowner is important. If a blind closes at eleven in the morning when the room still feels comfortable, they need to understand why. Otherwise, there is a good chance the automation will be switched off.
For installers and integrators, there is work to do beyond installing the equipment. Many homes already have the hardware – shutters, blinds, air conditioning in one or two rooms. What is often missing is coordination.
The job is increasingly about understanding how people use their homes, asking the right questions about their lifestyle and setting the controls around them. It is about making the different parts of the home work together, at the right time and in the right place.
The smartest homes do this almost invisibly. The blinds close before a room gets too hot. Second-floor windows open when the air outside cools down. Cooling is directed to the rooms where people need it.
The technology is there, but when it is working well, you barely notice it. And that’s exactly how it should be.
[1] Temperatures in Europe increase more than twice global average
[2] https://www.iea.org/commentaries/staying-cool-without-overheating-the-energy-system
[3] https://www.eia.gov/todayinenergy/detail.php?id=52558
[4] https://www.edrc.ac.uk/publications/socio-technical-drivers-of-air-conditioning-adoption-and-use-in-uk-homes/
[5] https://www.sciencedirect.com/science/article/pii/S0360132321005278