Designing vertical space

Designing a skyscraper means conceiving a vertical space as a complex system in which structure, aerodynamics, envelope, systems and mobility must integrate into a single organism.

Verticality is not the simple reiteration of a horizontal module, but a sophisticated balance between resistance to horizontal loads, environmental comfort, energy efficiency and rationalisation of routes and technical spaces.

Contemporary towers today represent the most advanced synthesis between technology, form and sustainability: every design decision – from geometry to construction system – arises as an engineering response to wind, seismic shocks, urban density and the need to optimize the use of materials.

From this perspective, vertical design is not only a structural challenge, but a new construction logic of urban space.

Vertical Space Structure: From Tube to Outrigger

The real evolutionary leap in skyscraper design occurred with the transition from traditional framed structures to “tube” structural systems, developed since the 60s.

This concept, introduced by engineer Fazlur Khan and masterfully applied in the Willis tower (formerly Sears Tower) in Chicago, is based on a simple but revolutionary logic: moving the main resistance of the skyscraper towards the outside.

In this scheme, the facade columns and the floors form a rigid envelope that works like a large box girder, capable of resist wind loads with a much more efficient use of materials.

As the heights increased, theoutrigger system, according to which horizontal beams or technical planes connect the core to the external columns, reducing oscillations and deformationsThe most recent versions – dissipative or virtual – improve comfort and durability without increasing internal stresses.

In any case, the design of vertical space requires that form and structure are conceived together: the integrated use of steel and concrete, combined with geometric optimization, allows to obtain leaner, more stable and efficient buildings from a material and energetic point of view.

Also read: "Recycled concrete for circular construction"

Aerodynamics and control: “confusing” the wind

When a building reaches high slenderness proportions, wind becomes the main design constraint, affecting both stability and occupant comfort.

The most effective aerodynamic solutions consist of model the shape of the building – through bevels, twists or progressive set-backs – to interrupt the formation of air vortices (vortex shedding) and reduce lateral forces.

An emblematic example is the tallest skyscraper in the world, Or the Burj Khalifa in Dubai, where the spiral geometry and subsequent setbacks were optimised in the wind tunnel for “disorient” the flows and limit the oscillations.

When the shape alone is not enough, however, the aim is to use dynamic damping systems, such as the tuned mass damper (TMD) of the Taipei 101 of Taiwan, a suspended mass of approximately 660 tons that reduces perceived displacement by up to 40%.

The aerodynamic design of the vertical space must therefore integrate from the very beginning Wind tunnel tests, damping devices and comfort criteria structural and environmental.

Envelope and performance: double skin and reduced loads

In a skyscraper, the facade is not just the architectural image of the building, but a real environmental machine. In addition to ensuring protection and comfort, in fact, the envelope actively participates in the control of the internal microclimate and the reduction of energy loads, and represents an aerodynamic system capable of influencing the behavior of the structure in relation to the wind.

An example we can take into consideration is the Shanghai tower – the tallest skyscraper in China and the third tallest in the world – where the 120° torsion of the main body and the double ventilated skin have made it possible to reduce wind loads by approximately 24%, while improving thethermal insulation.

The space between the two skins functions as a tempered air chamber that limits heat loss and allows for seasonal heat control, helping to reduce energy consumption and the use of structural steel.

To achieve similar results, it is essential integrate the envelope and systems from the early stages of the project, and include double-skin facades, mobile sunshades and high-performance glass. The design of the vertical space must also consider the division into functional zones andinsertion of regular technical plans to ensure maintenance, efficiency and long-lasting comfort.

Vertical mobility: sky-lobby, double-deck and “destination control”

Vertical mobility is a key element in ensuring efficiency and overall livability in skyscrapers.

Above 50-60 floors, in fact, the mere presence of traditional elevators is not sufficient: the most effective systems combine sky lobby (intermediate sorting plans) with fast shuttle lifts and local groups which serve the upper areas.

in Petronas TwinTowers in Kuala Lumpur, for example, the efficiency of vertical flows has been optimized by providing for the exchange between shuttle and local elevators on floors 41 and 42.

A significant technological evolution is also represented by the double-deck elevators, with two superimposed cabins that simultaneously serve two floors, reducing the number of compartments and increasing transport capacity.

When integrated with destination control systems, elevators can also intelligently manage user flows, assigning the cabin based on the requested floor and thus optimizing passenger distribution.

An approach that significantly reduces waiting times, limits intermediate stops, and contains overall energy consumption.

Also read: "Multi-storey car parks for public use: new urban needs"

Embedded carbon, materials, and “design for change”

Being built in vertical space, skyscrapers optimize the use of land and resources, but their environmental footprint largely comes from incorporated carbon in building materials.

According to the CTBUH (Council on Tall Buildings and Urban Habitat), today Council on Vertical Urbanism embodied carbon will represent approximately half of the emissions from new buildings by 2050, therefore it is it is necessary to reduce its use from the early stages of the project.

A sustainable vision includes structurally efficient shapes – such as torsion and set-back – which reduce wind loads and therefore the amount of steel and concrete.

THEhybridization of materials (composite columns, high-strength reinforced concrete cores, dry joints) allows for lighter and more removable structures, while the prefabrication reduces time, waste and construction site impacts.

Maintainable and recyclable facades also fall within the design for change principle, as they contribute to extend the useful life of the building.

To design a vertical space it is therefore necessary to consider the entire life cycle, focusing above all on efficiency, durability and emissions reduction incorporated.

The author of the cover photo is Elnur Amikishiyev on Depositphotos.com