Today's buildings hold the key to housing tomorrow's population, says professor

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Curbing new-build construction, renovating existing buildings at pace and rethinking how we use them: according to Philippe Thalmann, an urban and environmental economics professor at EPFL, these are the steps we'll need to take to both meet climate targets and accommodate an ever-growing population.

How can we make sure everyone has a decent roof over their head in the future? This question is more pressing than ever given the demographic, economic, climate and environmental challenges we face. Addressing them will require fundamental shifts in just about every sector of the economy, including construction. Our living habits will need to adapt, too.

Switzerland's population is forecast to keep growing and reach 10 million by 2050, up from 9 million today. It's also predicted to get older, with the number of people aged 80 and over to double from current levels. Tomorrow's homes will need to be designed with these trends in mind. And they'll need to help meet the net-zero target for 2050 set by the Swiss government and approved by voters in June 2023.

"The only way to achieve this target is to drastically curb the construction of new buildings and redirect the industry's workforce toward converting and renovating existing ones," says Philippe Thalmann from EPFL's Laboratory of Environmental and Urban Economics.

By reducing land take, cutting carbon emissions and taking other measures, such a change will also address environmental imperatives. But without building more homes, how can a country facing a persistent housing shortage possibly accommodate a growing population?

For Thalmann, the answer lies in a fundamental paradigm shift: rather than relentlessly building ever more homes, we should consider how to make better use of those already in place. Because, he argues, we already have more than enough space at our disposal.

Space in abundance

Switzerland's housing stock, when measured by surface area, has grown at a much faster pace than the population, increasing from 34 m² per capita in 1980 to 46 m² in 2020. Rooms aren't in short supply either, with 18 million of them for 9 million people, which equates to two rooms per person.

So-called "empty bedrooms" are a major problem—and not only in mountain chalets. Many primary residences have bedrooms that are used only when friends stay over, which have been left empty by adult children who've flown the nest, or are occupied part-time by separated couples with shared child custody.

"Having so much space is a luxury we can no longer afford," says Thalmann. "If we restructure our existing housing stock and return to the already comfortable standards of the 1990s, we should be able to accommodate the growing population."

As for Switzerland's housing shortage, Thalmann attributes it more to the inequitable allocation of a finite resource than to a genuine lack of homes: "We can basically divide Switzerland's population into two groups: one who bought generally older, larger homes a long time ago when prices were still reasonable, and one who recently moved or arrived in Switzerland, and whose only option is to live in a tiny apartment at an exorbitant price. So it's a matter of distributing our existing housing stock in a more equitable way."

The UN-affiliated International Resource Panel (IPR) also cites reducing floor area per capita as a key measure for achieving more sustainable housing. According to a 2020 IPR report, using residential buildings more intensively could cut construction-industry greenhouse gas emissions in the G7 countries by as much as 70% by 2050—a much greater reduction than could be achieved through other measures, such as improving recycling rates (14%–18%), designing more resource-frugal buildings (8%–10%) or using timber construction methods (1%–8%).

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Lowering expectations

This novel approach to sustainable housing implies challenging existing ideals, such as people's aspirations to own a detached property or a second home, and, more generally, lowering expectations around how much space we need to maintain a decent standard of living.

The challenge, of course, is that people could equate less space with less comfort. That's why Thalmann also stresses the benefits of smaller homes: "Half of urban dwellings are currently occupied by someone who lives alone. At the same time, we're experiencing a loneliness epidemic. This goes to show that having more space doesn't make you happy.

"Imagine if we were to offer these people more communal living arrangements. They'd have their own bedroom, kitchenette and private bathroom. But, as a bonus, they'd also have shared living spaces like a large lounge, a garden and other amenities. They'd almost certainly find this arrangement beneficial, not least because they'd be able to socialize with other members of their community."

Thalmann adds that people will likely explore new cohabitation models in the future. Living with roommates is becoming increasingly popular, and not just among students: older people are also taking an interest in this approach, which could go some way to addressing the challenges of an aging population.

Meanwhile, cooperatives are experimenting with new types of housing, such as cluster apartments and various kinds of eco-neighborhoods. "In short, we need to relearn how to live together," concludes Thalmann.

Why build when you can renovate?

If Switzerland is to meet its target of net zero by 2050, it urgently needs to renovate buildings to improve their energy efficiency.

"The math is simple—around 75% of the buildings in Switzerland need to be renovated in the next 25 years to reach the government's climate targets. That's a rate of 3% per year. But the way things currently stand, less than 1% of buildings are renovated annually," says Thalmann. His research group carried out a study in 2022 on energy-efficiency upgrades, as part of the Swiss National Research Program on the sustainable economy.

What can we do to speed up the process? Hire more construction workers? Thalmann points out that it's already hard to find enough qualified people. "Around 25% of construction industry workers are currently involved in renovation projects, with the remaining 75% involved in the construction of new buildings. If we're serious about meeting the government's climate targets, that ratio needs to at least be reversed."

Yet there are a number of obstacles, including economic ones, to making such a large-scale shift. "Construction firms aren't very keen on scaling back the number of new properties being built, because it's not in their interests," says Thalmann.

"There's also the issue of land value: property owners are often against initiatives to switch buildable land to other categories, such as to preserve farmland or protect biodiversity. Land loses a lot of its market value when it can't be built on. What's more, banks have a stake too through the mortgage loans they grant. It's a really complicated issue."

We also need to consider that not all property owners have the same means. Those with deep pockets, such as pension funds, government agencies and cooperatives, have mostly already upgraded their buildings to the latest standards. The trick is to convince the others to follow suit.

Many property owners have neither the resources nor the incentive to carry out the necessary work. Forty percent of homes in Switzerland are owner-occupied. In the case of condominiums, it's hard to get everyone to agree on what renovations should be carried out, and people generally don't all have the same financial capacity or ability to take out a loan. Regarding single-family homes, they've often been in the same family for decades and are now owned by retired individuals who may not have enough savings for extensive upgrades.

A bit of everything, including goodwill

The remaining 60% of homes are occupied by tenants. Half of these are rented out by individuals, many of whom rely on the rental income to supplement their pensions. These owners would rather hold on to the cash inflow than invest in energy-efficiency upgrades. And existing government subsidies generally aren't enough to change their minds.

Could the answer be to prohibit buildings with large carbon footprints? That's politically very complicated. Or to introduce new taxes, such as on fuel oil? That wouldn't go down well with voters, and wouldn't necessarily encourage property owners to renovate. What about offering additional subsidies?

"That could be an option, but it wouldn't force property owners to carry out the necessary work, which can be complex and could affect landlords' relationships with their tenants," says Thalmann. "But beyond that, why should taxpayers have to carry the burden? There's no magic solution. What's probably needed is a bit of everything: financial support, taxes and a little arm-twisting. Property owners need to give a little, too."

Provided by Ecole Polytechnique Federale de Lausanne