The Venice international architecture biennale has built itself a world of jargon. “Undisciplining”, “sub-dimensioning” and “sub-alternized” are just a few examples of neo archi-speak I collected, whilst taking in nearly 200 exhibits and listening to numerous curator talks during previews last month.

I am usually averse to made-up words. They make sense surprisingly quickly in Lesley Lokko’s “Laboratory of the Future”, though: an architecture event that demands vaults of imagination, because it is barely about buildings at all.

It feels like an insurrection, and perhaps these new words are necessary

This year’s biennale, themed and curated by the Scottish-Ghanaian academic, architect and novelist, involves little in the way of scale models of buildings in vitrines. Instead, Lokko has invited participants — “practitioners”, as she terms them — to imagine architecture as an art as much as a discipline.

Practitioners have responded to her call by expanding the definition of architecture to include film, education, sociology, history, politics, activism, performance, imagination and more — even people. “More buildings” is not always the answer to problems. It feels like an insurrection, and perhaps these new words are necessary to explain it all.

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This biennale — the 18th edition — manages to be both despairing in tone and energising in effect. As usual, it takes place across two main sites. In the “Special Projects” installations, on display within in the endless halls of the 16th century Codiere inside the city’s Arsenale, Lokko’s theme of Africa “decolonisation and decarbonisation” has captured the intellectual heart of the event from the traditional country pavilions over in the Giardini della Biennale (29 in total arranged a little like a zoo, though Russia’s is shuttered this year, a single guard the only sign of life). The continental shift in attention feels overdue.

There is a great deal of anxiety to be found in the special projects halls, over inequality, colonialism, injustice, material waste and humanitarian disaster. Despite the earnestness, Lokko’s youthful, multicultural curators were liberated by their brief. Their proposals for a better world were refreshing and inventive, and some of the best of the more practical ideas came from the UK’s African diaspora.

Take Gbolade Design Studio, a south London firm of architects whose installation explained a commission by Lambeth Council to renovate and expand the Lloyd Leon community centre on Coldharbour Lane in Brixton, home to the local domino club and soup kitchen.

Nigerian-British architects Tara Gbolade and Lanre Seun Gbolade showcased an approach that involved months of understanding how the centre operated before they designed anything at all.

They measured air quality, filmed domino games, talked to the neighbours and volunteered for weeks in the soup kitchen. It is not how most people are likely to imagine the day-to-day work of architects, but on this scale, it feels rational and intelligent.

Tara explained that this approach is “firstly, a series of connections” rather than a focus on the bricks-and-mortar constraints of building an extension. What they showed at Venice was an ideagram, photographs and a film. Now, she told me, the studio must wait for the council to give the green light to their plans before any real work can begin.

The average age of biennale participants this year is 43, falling to 37 in Lokko’s special projects. Their speeches were charged with energy; they were whooped and cheered at launches; their outfits were an enjoyable riot.

Tara wore a sunshine yellow, floor-length dress; Lanre a sharply cut, sugar-pink suit. Both architects were born in 1985. Throughout the biennale, I noted a diminishing number of sludge-coloured canvas chore jackets, and an increase in conceptual, futuristic footwear.

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Part of the pleasure of Venice is getting lost. The organisers’ mapping of the Giardini and the Arsenale is cursory, but perhaps that is the point — at the biennale, we are meant to relax and absorb ideas in serendipitous fashion, not to devise anything as uptight as a schedule.

Visitors stumbled in and out of blackened theatres, roamed open-air corridors and strayed into the inevitable immersive experiences. We were driven around in courtesy buggies in order to avoid the Arsenale’s muddy extremities, and we recovered in steamy bars. By the end of the second preview day, we were dazed by screens, audio interventions, textual explanations, the sheer volume of concepts. Occasionally, it was a relief to escape.

Beyond the two main venues, the world’s largest, grandest architecture event felt detached from the lagoon city. Venice’s visitors heaved on, oblivious. Still, the countless biennale celebrations, parties, dinners, launches, panel talks and collateral events continued all over town during preview week. Some were hushed and elegant; others were not grand at all.

The British party vibrated with youth, a far cry from other pavilions

The British Council throws one of the most-anticipated parties, this year at the 10th century Chiesetta della Misericordia, on Campo de l’Abazia. It is in honour of the opening of the UK’s pavilion, which was curated by a group of young architects, designers and artists: Meneesha Kellay, Sumitra Upham, Jayden Ali and Joseph Henry.

A rumour went around that someone had heard someone else recount how they had overheard a council illuminary on a plane from Heathrow, remarking that the party’s doors would have to close early, even to those with an invitation, because demand for tickets had exceeded capacity. The British contingent at Venice dashed to arrive early. They all seemed to get inside.

The scene was highly undisciplined: music throbbed; the crowd was ecstatic, the DJ revered. Everyone had to shout.

Boomers and Gen-Xers looked a little bewildered, though they appeared to enjoy themselves eventually. It was impossible not to find all that energy infectious.

The British party vibrated with youth, a far cry from parties held across town to celebrate the openings of other pavilions. Judging by the following day’s Instagram shots, these looked to be more prosecco-and-pashmina affairs than thumping club nights.

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There is a crevice between the radical definition of architecture proposed in Venice and what happens in the real-life biennale, however.

Take the Finnish pavilion in the Giardini, a huge draw for journalists lured by the promise of an intriguing, very Nordic way to “imagine the future of sanitation”.

This turned out to be “a declaration of the death” of the flushing lavatory, with a demonstration of an outdoor composting unit — waterless, odourless, here set up in a neat, wooden hut, commonly built by Finns outside their island summer houses. It works by separating liquid from solid waste to form usable compost and seems to involve a lot of time and patience, though mercifully no shovelling.

But there was no chance to try out the device, which curators promised would herald the death of the water closet. Inevitably, the facilities dotted around the Giardini were the same conventional, watery Portaloos to be found at open-air events all over the world.

Despite grand plans, radical revisionism and sheer brio on show in Venice, here was a missed opportunity. You could call it a failure on the part of the biennale to sub-alternize itself.