I recently had a phase of buying old furniture and then, armed with sandpaper, primer, brush and enamel, painting it all matte white. It was an attempt at minimalism, a reaction to the first five years of motherhood, which were filled with primary-coloured plastic and a lot of dirt. White, for me, was peace, visual clarity and maybe control, while across cultures and eras white has long symbolised holiness, purity, innocence, cleanliness and coolness.

In a less abstract sense, white reflects more light than darker colours, keeping surfaces cooler and hindering heat absorption. Zooming out from a burned-out mother’s private apartment and given the urgency of climate change, why not paint entire cities white – or at least the rooftops?

With 50 to 65 per cent of their surfaces in dark-hued materials such as tar and asphalt – which do not reflect light, but rather capture heat and radiate it back into the atmosphere – cities get much warmer than the surrounding natural landscape. The temperature difference can reach up to 9C. “This is called urban heat load,” says Dutch architect Ben van Berkel. Cities become “urban heat islands” in climate-control parlance and, on top of the discomfort of living in an oven (or paying too much for air-con), the dark surfaces can be significantly hotter than the surrounding air. Climate researchers and city-planners alike have been trying to devise multiple ways to reduce the load as cities grow – and green rooftops are perhaps the best-known example.

Another of their temperature-reduction initiatives is to simply paint rooftops (and, where possible, building façades or even roads) white. It’s not a new idea: think of the gleaming white cuboid houses on the slopes of arid Greek islands, or the mostly light-coloured rooftops and façades in historically hot cities such as Athens, Jerusalem, Beirut and Bangkok. The rest of the world, as it heats up, is catching on. In the past decade nearly 950,000 sq m of New York’s rooftops have been painted white through the CoolRoofs programme, which in part activates underemployed people and offers incentives to non-profits and landlords. Los Angeles is painting some of its asphalt streets white. Starting in 2015, Paris mandated rooftop environmental measures (either green roofs or white ones) and various Italian cities are running trials with white roofs. 

Beyond conventional white paint, new coatings for super-cool rooftops and surfaces are also emerging. In collaboration with Swiss paint company Monopol Colors, Ben van Berkel’s Amsterdam-based UNStudio developed The Coolest White, a paint that’s ultra-durable; it launched in early 2019. Made of hi-tech polymers and lasting up to 30 years, it’s engineered to really reflect sunlight. Darker materials absorb up to 95 per cent of the sun’s rays and release them back into the atmosphere; normal white paint reduces this to 25 per cent. The Coolest White paint brings this value down to just 12 per cent. This hugely reduces the need for coolants and maybe even saves lives: the most dangerous factor in recent heatwaves has been night-time overheating. Buildings don’t cool down enough overnight for weaker or older people to recover from the physical stress of trying to beat the heat during the day.

The Coolest White can even be applied to steel, fibreglass and aluminium; the first applications will soon be underway. “We are doing a major master plan in India, a tech campus in Bangalore, where many buildings will have this coating,” says Van Berkel, adding that The Coolest White appears whiter or shinier depending on the angle it’s seen from.

Architect Martin Haas of Haas Cook Zemmrich Studio 2050 in Stuttgart – a member of the German Sustainable Building Council –  also sees white surfaces as a step in the right direction. “In terms of climate change, it’s metaphorically five minutes to midnight, after all,” he says. “And we need to do all we can.” He’s still convinced that green rooftops remain the best option if they’re possible. “Whenever you have a flat surface, it’s better to not seal it. Stay in contact with Earth: make a green roof. It not only reflects, but also captures co2 and works as a storm water-management feature,” he says. But if you have to seal a roof “then do it in a bright whitish colour”, he adds. Van Berkel also says that his office, as well as Monopol Colors, is starting to think about other “coolest” colours, like The Coolest Green.

Haas recognises the need for greenery and light colours to creep back into city life in order to not only curb heat issues but to help people slowly reconnect with nature and, metaphorically, lighten up. As for me, I imagine future cities that have streets and façades of pure white (like too much of my furniture) or light green, baby blue or powdery pastels; some of them with greenery spilling down, others with farms on their rooftops. It sounds divine: quirky like the pictures in my daughter’s old Dr Seuss books; a lot more soothing and certainly cooler than our sooty, dirty, hot roads and rooftops. Van Berkel remembers reading something that Andy Warhol said: “Wouldn’t it be great if all the streets were made in carpet?” In white, please. 

Walking through Paris’s Passage de l’Opéra at the start of the 20th century, the French surrealist writer Louis Aragon hallucinated that the shopping arcade was bathed in submarine green light, as if the whole structure was deep underwater. A skinny mermaid – naked “down to a very low waistline”, with a tail of steel or rose petals – swam between walking canes in a shop window.

They tended to get like that, the surrealists. But Aragon points, too, to the lost spectacle of the shopping arcade. In the 19th and early 20th centuries, these arcades revealed an intoxicating collision of commerce, debate, round-the-clock eating and drinking, dance and play, which created a sensation among Parisian flâneurs and the booming urban bourgeoisie.

With no zoning regulations and little policing, arcades across Europe hosted brothels, bedsits, public baths, art galleries, theatres, hairdressers, cafés and shops selling books, stationery, coins and spices.

Passage de l’Opéra, which captivated both Aragon and the cultural theorist Walter Benjamin, was the first internationally acclaimed 24-hour destination. Through the day it acted as an illicit stock exchange (the so-called La Petite Bourse), then an all-night eating spot, art gallery, dancing destination and an after-party location for post-opera masked drinking. Structurally it was never more than a shopping street with a roof of iron and glass, lit up during the night with gas lamps. But it was the most important architectural form of the 19th century, said Benjamin: the architecture that birthed consumer society.

No retail location today fires such hot and confused passions. Least of all arcades, which often represent the stuffiest, most sterile streets of uniform luxury. It’s time to imagine a way back.

The 20th century saw hundreds of arcades abandoned for department stores in London, Milan and Paris – including Passage de l’Opéra – or else preserved as museum-like curios. But early in the 21st century the raucous arcade makes business sense again, as shop-floor sales volumes become secondary to exhibitions and Instagram-bait wrapped around a consumerist conceptual “experience”.

Arguably the best-known surviving arcade was an early standard-bearer for such reinvention. Galleria Vittorio Emanuele II, a glass-domed behemoth in Milan, was restored in 2015 by an unprecedented collaboration between Prada and Versace. The arcade, owned by the Commune of Milan, had hosted playful placemaking as early as 2003 when artists Elmgreen & Dragset’s “Short Cut” installed a white Fiat Uno hatchback and caravan trailer, crashing through the decorative mosaic floor.

Since reopening, the Renaissance Revival giant has doubled down. Fashion runways, including Prada Resort in 2018, have come to the raised Osservatorio level; new hotels have opened up in the wings; Milan Design Week commissions have arrived in the thoroughfare; and open-air cinema screenings have been hosted on the roof. For the city, the restoration has paid off. In 2018, Saint Laurent offered to pay €1m a year to rent a shop with a single window in the arcade.

New arcades have followed. Beaupassage Paris, which opened in 2018, is a wellness-branded development of dining spots from celebrity chefs who cumulatively claim 17 Michelin stars. The arcade conspicuously evokes the golden age of Paris passages, carving a new route through a 17th-century convent, a garage from the 1960s and an odd 1930s building by architect Henri Sauvage.

Beaupassage inches closer to the round-the-clock destination that Paris once boasted with Passage de l’Opéra. It has become known as a world-class food court and somewhere to share a bottle of natural wine, amid installation art and a mini forest. But still, it is hardly Aragon’s “ghostly landscape of damnable pleasures”.

Excitement arrives, instead, in less orderly places. Two strangely shaped developments have recently incubated gentrification-threatened communities: Sewoon Sangga, a repurposed Brutalist mega-complex in Seoul, and Peckham Palms, a hangar-like hub for south London hairdressers, cafés, and beauty salons evicted by a nearby regeneration project. These are buzzy buildings, full of surprises, where longstanding retailers and entrepreneurs are provided affordable units.

In Thailand, architect Alice Dietsch describes al_a’s 72 Courtyard as “space to breathe” amid Bangkok’s hectic main drag, Thong Lo. The client, a nightclub manager, allowed the firm to leave space for a garden at the centre of the development to surprise and delight visitors – even if it this meant giving up rental income that could have come with in-filling that space with shops.

Both 72 Courtyard and its grass-roofed rival The Commons (across the street) consciously plumbed history, from arcades to Bangkok’s own “community malls”: open-air mini-shopping centres that are centred on green space. The aim was to provide an equivalent to the European squares in a city that lacks parks.

Dietsch explains that her client was “a guy with a really good sense of what people need to have a good time”. Built around his nightclub, the development was innately 24-hour and inextricably linked to the heaving street of bars outside.

European and Asian arcade redevelopments often put the over-riding emphasis on strict “curation” of visitors’ experiences. Thong Lo loosens such programming, in a return to some basic principles of the arcade. “The architecture is in the background. It’s much more about the raw spaces and that’s where interactions between people are made possible,” says Dietsch.

There’s open potential for city centres to go beyond this, as the business of trading goods vacates. But some space for excitement, darkness and invention must be carved out before they can become – to quote the patron saint of arcades one last time – “the true sanctuaries of a cult of the ephemeral”. 

We need to put a plant in a pot because we have displaced it from its home in the ground. In a rather Victorian manner we keep it contained for our own pleasure; it’s wonderful to live among plants.

Keeping a plant alive in a container is a difficult task. Just ask the gardeners abseiling down the façade of Italian architect Stefano Boeri’s impressive Bosco Verticale in Milan. While you’re at it, why not glance over to the ivy-covered building next door, thriving with its roots in the soil, independent of human care. 

At the Venice Architecture Biennale 2018 our practice, along with Linda Tegg, exposed the difficulty of replicating conditions in the Australian Pavilion: thousands of plants in pots grew under artificial lights. This displacement considered what’s removed when we clear land. The plants in pots had to be cared for constantly, revealing how difficult it is to replace something once it’s removed. Climate change played out inside the gallery, where temperature and humidity controls isolated the Australian plants from Venice’s humidity.

Reflecting on how hard it is to keep a potted plant alive might guide us in a less artificial approach to how we bring plants back to places where they have been removed through urbanisation. What if we just put plants in the ground where they can communicate with each other and share water and nutrients through their mycorrhizal networks?

Are we ready to allow plants to live on their own terms? “Weeds”, lichen and moss spontaneously grow in our cities. Urban environments are capable of remarkable diversity. If one can’t empathise with the contained plant then the growing body of evidence of the benefits of vegetation in urban development is compelling. They include an increase in property values, crime reduction, human health, urban island heat effects, storm-water management and mitigation of climate change events. Architecture and urban design simply need to make more space for plants to have their roots in the ground.