The biggest and brightest cities in the world are known for their skylines, where towers and skyscrapers made of glass and steel jostle with one another, vying for our attention.

Skyscrapers are the hallmark of bustling and healthy cities – a sign that a lot of people want to live and work within a few square miles.

In some British cities, like Manchester, the race to the sky is only just getting underway.

Yet in London, building skywards has taken a considerable downturn recently, with the NLA annual Tall Buildings Survey showing that only 18 projects over 20-storeys high were completed in 2017, down from 26 the year before.

This slowdown is also visible in the amount of planning applications submitted for tall buildings in the last year, which fell by 10 per cent.

So, when it comes to housing supply, how do we find new ways to solve old problems?

One design solution is through the unlocking, and development of air rights: that is, the right to develop the "air space" above a property into additional housing units.

In London and other dense urban centres, where available and affordable sites for development are few and far between, intensifying the land use of existing sites is a popular option that brings with it a whole host of benefits.

The most immediate benefit of unlocking air rights is to the freeholder, who by owning the property, will also own the space above it.

Subject to planning permission, these air rights can be sold or leased to enable the construction of an air rights development, which will create an additional property – or a number of properties – above the building. In most cases, this involves a substantial financial windfall to the freeholder, while adding meaningful value to the wider property.

And, as advances in modular construction and green roof technology continue unabated, more and more properties are now suitable for air rights development.

What’s more, unlike building from the ground-up, these developments sew homes into the existing urban fabric of the neighbourhood. In Putney, for example, Fruition Properties has built the UK’s first ever crowdfunded air rights housing development, funded by investment platform Propio.

It's crucial to ensure that density comes without disruption, so that additional homes are only introduced to those neighbourhoods that are already supported by local infrastructure and have a functioning community.

Ultimately, despite the fact that skyscrapers are the hallmark of any city, plans to build upwards in London and other UK cities are all too often met with a defiant chorus from the nimbys.

Such vehement opposition to tall buildings in urban locations, combined with a chronic lack of sufficient housing in cities, means that there is a need to establish a happy medium.

And this happy medium can only be achieved by finding innovative ways to create density beyond the new build model. Traditionally in property, we associate value with land and buildings that are built upon it.

But when it comes to air rights, you need to crane your neck, because the sky's the limit.

By Daniel Wittenberg.

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