In many cities around the globe, a skyscraper building boom threatens to diminish the amount of sunlight that reaches street level. Sydney and Melbourne share top honors for skyscrapers in Australia, both claiming 31 structures over 150 metres.

Brisbane tallies 13 skyscrapers, the Gold Coast comes in with seven, Perth has five, and Chatswood has two. Approximately 50 more are under construction, approved, or proposed. Will the residents of tomorrow's cities be starved of sunlight?

Manhattan is currently home to 41 towers of 700 feet and taller, with 34 more underway or proposed. London takes it even further, with more than 230 new towers planned and under construction.

While this may be welcome news for architects, developers, and apartment owners in those towers, what’s the effect at street level? Will sunlight be restricted for everyone but the wealthy?

No, that won’t be the case, but there will certainly be districts where dense blocks of towers will block much of the sunlight from reaching the street level. However, it’s not just condominium projects for millionaires and billionaires that are creating more shade.

Many dense cities are facing intense demand for affordable housing, which must compete with market-rate projects for buildable land, leading to calls for taller buildings. According to The Washington Post, New York Mayor Bill de Blasio has proposed 88,000 affordable housing units to be built over the next 10 years. Toronto has built more than 67,000 units in the last five years. With a limited supply of land, municipalities will change zoning laws, and many of these projects will be built taller than would have been considered a decade ago.

As zoning rules now stand, skyscrapers are not permitted everywhere, so zoning remains a bulwark against over-densification through excess building heights. Air rights, not commonly used in Australia, are another tool for both limiting and increasing building heights. Air rights are the legal right to use the space above a building. Developers can purchase air rights from adjoining structures in order to increase the size of their projects.


Australia’s dense urban areas are facing the same problems, and in need of solutions for both the practical and social issues associated with taller buildings and loss of sunlight. In addition to zoning rules, technological solutions might also play a role. By using software to track sunshine, architects and planners can manipulate the shape, orientation, and spacing of towers to reflect light into the plaza spaces at street level.

Alex Washburn of architecture firm NBBJ, and formerly the chief urban designer for New York City under Mayor Michael Bloomberg, tackled the challenge with design he calls “heliostatic massing.” While working on a large-scale project in 2008, he wrote that his team struggled to fit in all the required building area on the site while also making way for sunlight in the central park area. Washburn and his team wondered about reflecting sunlight with the towers themselves, and tested the idea.

“We looked for property that was adjacent to a shaded public space (in the northern hemisphere,)” he wrote, “typically to the north of that space, where a building would be ideally positioned to bounce sunlight all day), and where the surrounding lots would not allow future development to block the sunlight.”

Architect Christian Coop, also with NBBJ, explains the “No Shadow Tower” here:

If that concept calls to mind London’s “Walkie Talkie” and its penchant for melting cars at street level, Coop addressed that concern in an article.

“Unlike other reflective towers,” he wrote, “which have concave surfaces that focus the sun’s rays like a magnifying glass, No Shadow Towers reflect pane by pane. This creates pools of sunlight and a moving light show on the ground, reducing shade up to 50%.”

Though this type of design is not part of zoning requirements yet, it offers the potential to mitigate some of the objectionable facets of skyscrapers, making them more hospitable for all users of a city. As capital concentrates in cities around the world and cities further densify, Washburn noted that “regulations such as these could improve the quality of life for all city residents, not just the occupants of a particular building.”

  • Steve, this is a great and timely article. Melbourne is losing its street character and pleasure with large buildings now increasingly dominating its streets. Sydney is a few years behind. The race for density will slow as the compromises to lifestyle and the complexities of managing and maintaining some of these buildings manifest themselves. With 20 – 30% of density sales going to offshore purchasers the number of absent owners and occupiers adds another dimension. While these properties are a store of wealth for some, the cost of maintenance is not seen as part of the equation. Some strata managers are already reporting the difficulties of getting offshore owners to support levies for necessary backlog maintenance and repairs. The realities of the new investment economy will also come to bear as short term renters such as airbnb and others add to the mix. There is both good and bad here. The downside is that the need for affordable (not social housing) private rental offering secure longer term tenures for the people that make our cities work is not being met. All governments have failed to understand that a professionally managed asset class for this sector is important. Owners of properties such as these have a longer term investment horizon and that includes the amenity at the street and neighbourhood level. They know that this underpins value. Developers and small often negatively geared investors have different, short term objectives that are the root cause of buildings now shadowing our cities. The voices of pro-density have had public policy sway that is disproportionate to their representation of the broader public interest. Property value correction will help rectify this.And shadows will be their legggacy

  • This looks like a bright intiative, we should see much more of this technology and design being used, especially for high-rise monoliths.
    Most importantly to this issue, Right to Light needs to be enshrined into law now in every developed country, we cannot do it once overdevelopment has already become a problem and it is too late to remedy the problem.
    The great thing about solar modelling and shadow modelling is the way architects like NBBJ and engineers can wow the public with impressive visuals — unfortunately the software is exclusively used and operated by these firms to further their agenda (increase rela estate yeilds for clients), and the regulatory authorities haven't the know-how or the tools to properly assess whether those models are accurate.
    Little has changed since the days of hand-drawn shadow diagrams, and while they look cool, it all means very little in reality if an experienced designer wants to game the system and tweak the data, it is not routine but until local governments mandate provision of 3D BIM models for every project, to be assessed on their own software, there is no way to control this prevalent, sneaky practice.