The simplest sustainable interventions are the ones we keep designing away

In Barcelona, balconies are so woven into the rhythm of daily life that you stop noticing them. Until you do. Little theatres above the street, each one a buffer between the quiet of a private room and the noise of the city below. Pause on any residential street in the Eixample and you can read the whole social history of a building from its balconies alone.

We visited Barcelona recently as a studio. Not a research trip, just a few days away. But you cannot spend time in that city as an architect without coming back with questions. The main one, for us, was this: why does a city that was largely built in the nineteenth century feel more climatically intelligent than most of what gets built in London today?

The answer, in part, is balconies. But not balconies as decoration. Balconies as passive design infrastructure.

A Gaudí balcony in Barcelona - where art, shade and passive design merge to soften the street and connect home to city life.

What a balcony actually does

A deep balcony on a south-facing elevation shades the room behind it in summer, when the sun is high, and lets low winter sun through when you need the warmth. It creates a thermal buffer at the building edge. It slows down wind before it hits the glazing. It gives you somewhere to grow plants, which cool the immediate microclimate, absorb a small but non-trivial amount of carbon, and soften the street below. It provides natural ventilation without mechanical assistance.

None of this is new knowledge. Mediterranean cities have understood it for centuries. The old saying that if the sun does not come through the balcony, the doctor will come through the door captures something that building physics now confirms: daylight, fresh air, and connection to the outside are not amenities. They are health infrastructure.

And yet in London, in 2025, we keep designing these things away.

Why they disappear

The logic is straightforward and, from a short-term development perspective, not entirely wrong. A balcony costs money to build, requires structural depth, needs waterproofing, and reduces the net internal floor area that can be sold or rented. On a tight urban plot with a cost consultant looking at every line item, it is an easy cut.

What gets replaced is usually glazing. A full-height window reads well on a CGI. It photographs beautifully. It sells the idea of light and openness without the structural and spatial cost of a genuine outdoor threshold. And so another building goes up that looks generous from the outside and performs poorly from within: overheating in summer, cold at the edges in winter, entirely dependent on mechanical systems to maintain the comfort that a well-designed balcony would have contributed to for free.

We see this pattern regularly in prime London residential development, including in the neighbourhoods where RISE works. Beautiful buildings, thoughtfully detailed, that have had the passive design logic quietly removed in the value engineering stage.

The threshold is the point

There is something that gets lost beyond the energy performance argument, and it is harder to quantify but no less real. A balcony is a threshold. It is the space between being inside and being outside, between private and public, between solitude and the street. It is where you stand with a coffee in the morning before the day properly starts. Where a child leans out to watch something happening below. Where a pot of something green gets watered on a Tuesday.

These are not trivial moments. They are the texture of urban life, and buildings that have no threshold, no negotiated edge between inside and out, tend to produce a particular kind of isolation. You are either in or you are out. The glass wall gives you the view but not the experience.

Barcelona's residential streets feel alive in a way that many newer London developments do not, and we think the balcony is a significant part of why. Not because balconies are charming, though they often are. Because they create a condition of permeability, a softness at the building edge that makes a street feel inhabited rather than occupied.

What this means for how we design

At RISE, we push for external thresholds on every project where the brief and the planning context allow it. Sometimes that is a balcony in the conventional sense. Sometimes it is a Juliette with deep reveals that shade the room behind. Sometimes it is a planted terrace at first floor level, or a generous threshold step between a kitchen extension and a garden that does the same work at ground level.

The specific form matters less than the principle: buildings should have edges that negotiate between inside and outside, that provide shade and buffer and a reason to be at the perimeter of a room. This is good passive design. It is also, we think, good urbanism.

The simplest sustainable interventions are almost always the ones that have been understood for centuries and keep getting removed because they are inconvenient to the spreadsheet. Balconies are one of them. Deep window reveals are another. Operable windows. Planted roofs. External shading.

None of these require new technology. They require the decision, made early enough in a project, to treat the building envelope as something that works with the climate rather than against it.

If you are working on a project in London or Barcelona

If you are planning an extension, a new build, or a significant refurbishment and want to talk about how passive design principles can be woven into the architecture from the outset, we would be glad to have that conversation early. The decisions that make the most difference are almost always the first ones.

We offer a free initial consultation for residential and development enquiries.

→ Email us at architects@risedesignstudio.co.uk
→ Or call the studio on 020 3947 5886

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