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The Urban Developer
Developers of a New York skyscraper have been ordered to remove as many as 20 floors from the top of its recently completed project on the Upper West Side.

The 200 Amsterdam Avenue development, being delivered by SJP Properties and Mitsui Fudosan America, has been found to have exceeded zoning limits after developers “gerrymandered” a 39-sided zoning lot in order to add height and bulk to the project.

The decision, handed down by supreme court judge Justice W Franc Perry, marks a watershed moment for community groups who opposed the 204 metre tall project on the grounds that the developers used a zoning loophole to upsize the project to comprise 112 apartments.

The court found that while it is common for developers to purchase the unused development rights of adjacent buildings, the developers in question had put together a highly unusual zoning lot to take advantage of the development rights.

Community groups opposing the tower went to court after their request to stop construction was rejected by New York City’s Department of Buildings.

Last year, the New York State Supreme Court ruled in favour of the community groups and ordered the city’s Board of Standards and Appeals (BSA) revisit the matter.

Despite the court order, SJP Properties and Mitsui Fudosan America continued with the construction of the high-end residential project, which recently topped out.

“200 Amsterdam entirely conforms with all zoning rules, as earlier upheld by equally the DOB and the BSA, the two metropolis agencies with the most important responsibility for interpreting NYC’s zoning codes,” SJP Properties and Mitsui Fudosan America said in a statement.

“We continue to make construction progress and look forward to delivering a building that will significantly benefit the neighbourhood and New York City.”

Attorneys representing the developers plan to appeal the ruling on the grounds that the project was fully compliant with the city’s zoning resolution.

At this point it remains unclear how many floors might need to be deconstructed from the 52-storey tower, but under one interpretation of the law, the building might have to remove 20 floors or more to conform to the regulation.

The Elkus Manfred-designed tower, which is located a few blocks from Central Park, at its current height would boast panoramic views of the Hudson River, Empire State Building and World Trade Centre.

The project also offers high-end amenities including an indoor swimming pool, fitness centre, conservatory, virtual golf room and a residential lounge.

The decision isn’t the first time a ruling like this has been passed down in the state of New York.

In 1991, developer Laurence Ginsberg was forced to reduced a development at East 96th Street by 31-storeys to 19-storeys after it was found to be inside a special Park Avenue zoning district, which limits building heights.
Michael Young
Construction is moving along at 66 Hudson Boulevard, aka The Spiral, the eighth-tallest skyscraper under construction in New York City in YIMBY’s annual countdown. Designed by Bjarke Ingels Group, the massive commercial office tower is rapidly ascending toward its 1,031-foot-tall parapet over the Midtown neighborhood of Hudson Yards. Tishman Speyer is the developer, Turner Construction Company is the construction manager, and Banker Steel is in charge of fabricating the 66-story, $3.7 billion supertall.

Photos show the superstructure rising in pace with Norman Foster‘s 50 Hudson Yards across West 34th Street.

Both projects have risen at a substantial pace since going vertical earlier in the year, and it will be interesting to see which of the two supertalls will top out first. The Spiral currently appears to be roughly a quarter of the way to its summit as it ascends around the concrete core, which continues to precede the steelwork in formation. Work should accelerate further as each successive setback reduces the size of the floor plates.

There are several floors covered with white plastic sheets toward the end of the building along Tenth Avenue, likely to contain the spray of fireproofing material for the steel columns and beams. The fireproofing on the western half of the floors facing Bella Abzug Park is finished, and the metal clips to hold the curtain wall are already in place and awaiting the installation of the façade’s reflective glass panels. The signature spiraling form of the architectural design will become more noticeable once the envelope starts to climb all four sides.

The Spiral is expected to be finished around 2022.
SHoP Architects
One doesn’t need to visit New York City in order to understand that the city’s skyline is undergoing drastic change, both within and—increasingly—outside of Manhattan.

In an attempt to better understand the micro- and macro-forces at play shaping the city’s skyline, we’re taking a look at three recent distinctive tower projects designed by SHoP Architects in partnership with JDS Development, Property Markets Group and Spruce Capital Partners, including: 111 West 57th, a spindly supertall under construction on Billionaire’s Row; the American Copper Buildings, two metallic skyscrapers overlooking the FDR expressway; and 9 DeKalb, a forthcoming supertall tower set to become Brooklyn’s tallest building.

Together, along with a forthcoming set of acrobatic high-rises slated for the Brooklyn waterfront that SHoP has also had a hand in crafting, the featured buildings highlight several of the dynamic conversations taking shape within the realm of skyscraper design, as issues of extreme height, massing, historic preservation, and environmental performance play out across the city’s (and the world’s) evolving skylines.

A Skyline in Flux

New York City’s constantly growing skyline has reached new and dazzling heights during the second decade of the 21st Century.

The steady stream of neck-straining renderings for the row of supertall towers on the southern edge of Central Park, for example, has created what some have called an “accidental skyline” shaped in part by tricky real estate maneuvers, the exploitation of zoning codes, and piles of cash that nearly rival the heights of the towers themselves. On Manhattan’s western edge, the Emerald City-like Hudson Yards development has sprung up over the last half-decade as an equally controversial set of sky-piercing buildings, their slanting, chiseled forms broadcasting ostentatious luxury, corporate retro-futurism, and America’s frothy economy all at once. The ever-multiplying clusters of residential and office towers taking shape in downtown and northern Brooklyn, in addition, have extended western outposts of the city’s world-famous skyline, while the relatively staid high-rises in Long Island City, Queens, as well as those located across the Hudson River in Jersey City and Hoboken, indicate that New York’s decade-long post-recession growth spurt is reshaping the entire region rather than merely a few choice neighborhoods.

As incredibly tall buildings have advanced and proliferated across the New York area, the conventions of skyscraper design have been somewhat upended. Monolithic glass curtain walls are becoming less common in new proposals, for example, as designers work to incorporate concerns over environmental performance and facade modulation into their work. At the same time, street-level design has grown more rich and people-friendly over the years, with landscaped plazas and pedestrian retail designs back en vogue, as well. Simultaneously, as land-use and zoning regulations have been massaged into submission via a proliferation of re-zoning initiatives and clever lot arrangements, and as a result, towers have sprung up that dive into existing historic structures, hang daintily over them, or land neatly right beside them, challenging the conventions of historic preservation thinking, both on the street and across the sky.

All told, New York City’s skyline, always shaped by the interlocking considerations of aesthetics, finance, and gravity, is alive and growing.

SHoP is Transforming the Skyscraper

Central to this transformation have been the efforts of SHoP Architects, an architecture firm founded in 1996 and based out of Manhattan’s Woolworth Building—a tower that itself stood as the tallest in the city for nearly two decades after being built. In recent years, the firm has undertaken an increasingly aggressive building spree across New York City (as well as regionally and across the globe) that is beginning to give form to a collection of unique and forward-looking skyscrapers. The office, headed by a multi-partner team with experience in design, real estate, and other building endeavors, works methodically to iterate its way toward convention-defying works of architecture, often partnering directly with developers and builders to craft these dramatic and provocative buildings. Such is the case for the collection of projects showcase
Inspired by the apocalyptic imagery from climate change projections, sculptor David Černý and architect Tomáš Císař from the studio Black n´ Arch have proposed a visually striking skyscraper that’s sparked controversy with its inclusion of an enormous shipwreck-like structure. Dubbed the TOP TOWER, the project proposed for Prague rises to a height of 450 feet, which means that if built, the tower would be the tallest building in the Czech Republic. The project is led by developer Trigema who aims to create a multifunctional, LEED Gold high-rise that includes rental apartments, a public observation area and commercial uses on the lower floors.

TOP TOWER has been proposed to be located near the metro station Nové Butovice on the new nearly one-kilometer-long pedestrian zone in Prague. This location is outside of the protected urban conservation zone and would be far enough away from the city center that it would not disrupt the historic city skyline. Taking advantage of its height, the building would offer a public observation area at the highest point of the building where visitors can enjoy a 360-degree panoramic view of Prague.

Rental housing will make up the majority of the mixed-use TOP TOWER, while offices, retail and a multifunctional cultural center will be located on the lower levels. Parking will be tucked underground. The rusty shipwreck-like sculpture integrated into the building will offer opportunities for outdoor spaces and additional landscaping.

“We have been preparing the TOP TOWER project for more than two years and the final version was preceded by eight other alternative solutions. During this time, we have collected and are still collecting suggestions from experts, state and local authorities, and of course the local public, whose representatives have already been and will continue to hold a number of participatory meetings,” says Marcel Soural, Chairman of the Board of Trigema a.s. Trigema estimates that the construction for TOP TOWER will begin in 2021 and take less than three years complete.

Benjamin Minnick
When finished in August 2020, the 850-foot-tall building will be the city's second-tallest skyscraper.

Workers on Thursday raised the final steel beam into place atop the 58-story Rainier Square tower at Fifth Avenue and Union Street in downtown Seattle.

A news release from developer Wright Runstad & Co. says ironworkers and other tradespeople have put in 500,000 hours of labor so far on the $570 million project. When finished in August 2020, the 850-foot-tall building will be the city's second-tallest skyscraper, below the 933-foot-tall Columbia Center.

Rainier Square will have 722,000 square feet of office space, 191 luxury apartments on floors 39 through 58, nearly 80,000 square feet of retail space and a seven-level underground parking garage. Apartments will be available in one-, two- and three-bedroom layouts, with penthouse units on the top.

Runstad says it will be one of the largest mixed-use buildings in the country, at 1.17 million square feet.

Amazon leased all of the project's office space, but earlier this year decided to sublease instead of occupy it. Much of the retail space will be taken by a 20,000-square-foot PCC Community Market and an Equinox fitness club. Runstad says additional tenants will be announced closer to opening.

Apartment marketing is expected to start early next year.

The project is on the north half of the block, where the old Rainier Square shopping center once stood. The building's east facade slopes up to its 40th floor.

Structural engineer Magnusson Klemencic Associates designed a unique concrete-filled composite plate sheer wall core for the building. The system allowed workers to assemble two floors per week. MKA says the system uses two steel plates connected by steel cross ties that are then filled with high-strength concrete — there's no rebar.

Lease Crutcher Lewis is the general contractor and NBBJ is the architect.

Runstad has an 80-year ground lease on the site from owner University of Washington.

Most of the project's financing is coming from a U.S. pension fund advised by J.P. Morgan Asset Management.
Oxford Properties
The Canadian metropolis is going vertical as a building spree of billion-dollar projects continues

A newly proposed mega-development in downtown Toronto was announced late last month, highlighting how the city’s vertical growth spree continues to pick up momentum.

The $2.7 billion ($3.5 billion Canadian dollars) Union Park project, helmed by Oxford Properties Group, a partner in New York’s Hudson Yards, will be one of the largest mixed-use project in the city’s history.

Set on four acres just north of two city landmarks, Rogers Centre (the sports stadium formerly known as the SkyDome) and CN Tower (the city’s iconic communications and observation tower), the development will consist of twin curved 58- and 48-story office towers and apartments surrounded by newly landscaped public parkland, and bring 4.3 million square feet of new mixed-use office, residential, and retail spaces to downtown.

This development comes at a time when other large-scale mixed-use projects, such as the 12-acre Sidewalk Labs-backed Quayside smart city project and The Well, a 7-acre “21st century city,” highlight the city’s rapid expansion. A growing tech industry and expanded immigration, among other factors, have fueled a Toronto condo boom; there are 400 proposed high-rise projects in the pipeline, according to Rider Levett Bucknall a global construction firm, and the city has the most construction cranes in North America.

According to the Financial Post, other forthcoming Toronto mega-projects include CIBC SQUARE, a two-tower development adding 3 million square feet of space and a new Microsoft office, and a plan by Cadillac Fairview and Investment Management Corporation of Ontario to develop 1.2 million-plus square feet of mixed-use office and retail at 160 Front Street West.

Union Park fills a gap in the market, said Oxford vice president Carlo Timpano, shifting the financial sector of the city west by providing additional office space for expansion, and adding needed retail and residential space for an underserved part of the downtown core.

The floors for the office portion of the development are designed to measure 100,000 square feet, providing the large, open floor plans favored by tech tenants.

Union Park will also add public amenities to the downtown, including an enclosed winter garden for all-season recreation and a new two-acre park built atop a covered rail line. The park will point towards Lake Ontario, helping provide a new pedestrian pathway linking the business district with the waterfront.

Designed by Pelli Clarke Pelli Architects, which designed San Francisco’s Salesforce Tower, with local support from Toronto’s Adamson Associates, the project will be spread across two towers, and add 800 apartment units and 200,000 square feet of retail. The city’s PATH underground pedestrian tunnel system will be expanded to connect to the Union Park Project.

The two-acre park, which will cap the Union station rail corridor between Blue Jays Way and the John Street Bridge, is designed by OJB Architects. It’s not the first such project under development; the city’s own Rail Deck Park, a proposed 21-acre green space that just won an appeal against stopping its construction, will be right around the corner.

Oxford, which is starting the public engagement and municipal approvals processes now, expects to begin construction in 2023 and finish within five to six years.
Paul Riddle
The Victory Plaza build to rent development, comprising two 26 and 29-storey towers, is sited on the former London 2012 Athletes’ Village

The 482-home build for rent development consists of nine-storey podium buildings designed using heavy masonry construction and punched openings. The two towers rise above with façades composed of glazing and bronze-ribbed panels framed in a precast stone grid.

Together with contractor MACE, Lifschutz Davidson Sandilands developed an innovative construction method involving major prefabrication and a vertically rising four-level ‘jump factory’ able to complete a storey in under 55 hours, in order to save time and minimise disruption.

Amenity spaces include residential roof gardens on the podiums and a large roof garden facing on to the main road, as well as balconies and winter gardens.

At ground-floor level, aside from large entrance lobbies, shops and restaurants provide active frontages around the plot, with large overhanging canopies in precast concrete creating shelter from wind and rain.

The scheme is the first phase of an LDS masterplan for Qatari Diar/Delancey to develop 2,000 privately rented apartments.

Architect’s view

The greatest challenge with the project was to create a building that acted as a suitable backdrop to Victory Park. The towers certainly create a powerful sense of place and point of arrival in Victory Plaza, but we have anchored them to the site with robust, nine-storey podium buildings built from hand-laid brick. The towers are further integrated with public space between the building clusters, residential roof gardens on the podiums and the roof garden facing the main road.

Because the buildings are for private rental, they have to be flexible to accommodate changing living patterns, so have identical cores and floorplates, with ‘plug and play’ fittings that rationalise maintenance and replacement, which means the flats can be rented speedily and can change use or tenure over time. To improve quality and reduce delivery times and disruption to existing residents, we worked with MACE to come up with the ‘jump factory’ method of construction that involved significant prefabrication, which completed every storey within an incredible 55 hours.

Client’s view

Having completed two buildings in the London 2012 Athletes’ Village, we appointed Lifschutz Davidson Sandilands to undertake a review of the East Village masterplan, focused on the five undeveloped plots. This next phase, comprising a further 2,000 apartments, shops and leisure facilities, was to ensure the area’s legacy and transformation from the Olympic Games to an established London neighbourhood of 5,000 homes.

Our commitment that our homes be for the private rented sector meant the long-term stewardship of the area was critical to the success of the development. We worked closely with LDS to define a suitable typology for this emerging sector, increasing apartment sizes in response to sharers and families looking for spacious, long-term homes and prioritising designs that supported ongoing maintenance.

Seven years later the first plot, Victory Plaza, is complete and the architect’s commitment to quality materials and innovative, off-site construction has delivered two elegant and efficient towers with podiums that establish the emerging context of this new neighbourhood.

Peter Holroyd, construction director, Delancey
United Nations Photo/Flickr., CC BY-NC-ND
New York Mayor Bill de Blasio has declared that skyscrapers made of glass and steel “have no place in our city or our Earth anymore”. He argued that their energy inefficient design contributes to global warming and insisted that his administration would restrict glassy high-rise developments in the city.

Glass has always been an unlikely material for large buildings, because of how difficult it becomes to control temperature and glare indoors. In fact, the use of fully glazed exteriors only became possible with advances in air conditioning technology and access to cheap and abundant energy, which came about in the mid-20th century. And studies suggest that on average, carbon emissions from air conditioned offices are 60 percent higher than those from offices with natural or mechanical ventilation.

As part of my research into sustainable architecture, I have examined the use of glass in buildings throughout history. Above all, one thing is clear: if architects had paid more attention to the difficulties of building with glass, the great environmental damage wrought by modern glass skyscrapers could have been avoided.

Heat and glare
The United Nations Secretariat in New York, constructed between 1947 and 1952, was the earliest example of a fully air conditioned tower with a glass curtain wall – followed shortly afterwards by Lever House on Park Avenue. Air conditioning enabled the classic glass skyscraper to become a model for high rise office developments in cities across the world – even hot places such as Dubai and Sydney.

Yet as far back as the 19th century, horticulturists in Europe intimately understood how difficult it is to keep the temperature stable inside glass structures – the massive hot houses they built to host their collections. They wanted to maintain the hot environment needed to sustain exotic plants, and devised a large repertoire of technical solutions to do so.

Early central heating systems, which made use of steam or hot water, helped to keep the indoor atmosphere hot and humid. Glass was covered with insulation overnight to keep the warmth in, or used only on the south side together with better insulated walls, to take in and hold heat from the midday sun.

The Crystal Palace

When glass structures were transformed into spaces for human habitation, the new challenge was to keep the interior sufficiently cool. Preventing overheating in glass buildings has proven enormously difficult – even in Britain’s temperate climate. The Crystal Palace in Hyde Park – a temporary pavilion built to house the Great Exhibition of the Works of Industry of All Nations in 1851 – was a case in point.

The Crystal Palace was the first large-scale example of a glass structure designed specifically for use by people. It was designed by Joseph Paxton, chief gardener at the Duke of Devonshire’s Chatsworth Estate, drawing on his experience constructing timber-framed glasshouses.

Though recognised as a risky idea at the time, organisers decided to host the exhibition inside a giant glasshouse in the absence of a more practical alternative. Because of its modular construction and prefabricated parts, the Crystal Palace could be put together in under ten months – perfect for the organisers’ tight deadline.

To address concerns about overheating and exposing the exhibits to too much sunlight, Paxton adopted some of the few cooling methods available at the time: shading, natural ventilation and eventually removing some sections of glass altogether. Several hundred large louvres were positioned inside the wall of the building, which had to be adjusted manually by attendants several times a day.

Despite these precautions, overheating became a major issue over the summer of 1851, and was the subject of frequent commentaries in the daily newspapers. An analysis of data recorded inside the Crystal Palace between May and October 1851 shows that the indoor temperature was extremely unstable. The building accentuated – rather than reduced – peak summer temperatures.

These challenges forced the organisers to temporarily remove large sections of glazing. This procedure was repeated several times before parts of the glazing were permanently replaced with canvas curtains, which could be opened and closed depending on how hot the sun was. When the Crystal Palace was re-erected as a popular leisure pa
Gensler, via thyssenkrupp
New North American headquarters of elevator giant thyssenkrupp is called company’s highest profile project

One of suburban Atlanta’s most prominent towers is officially a go.

Fortune Global 500 company thyssenkrupp Elevator broke ground this week on its new North American headquarters next door to Cobb County’s burgeoning mixed-use hub The Battery, home of the Atlanta Braves’s stadium.

Scheduled to open in 2021, the headquarters complex will be punctuated by a 420-foot elevator test tower that would be Cobb’s tallest building. For context, Sandy Springs’s “King and Queen” towers at Concourse Corporate Center each stand about 100 feet higher, ranking them among the tallest suburban high-rises in the nation.

According to officials with Atlanta-based Collins Project Management, which is spearheading the tower’s development, the project will be thyssenkrupp’s most “high-profile” in the country.

Atop the vertical testing facility, three floors will be reserved for special functions, providing panoramic views of the city, officials revealed this week.

Beyond the tower, the project will include an adjacent, shorter building for thyssenkrupp’s business and engineering functions.

The combined projects are expected to cost $200 million. Officials have said the complex could house some 900 full-time thyssenkrupp employees, lured in no small part by Cobb tax breaks and other incentives.

As development goes, the groundbreaking marks another feather in the rapidly evolving Cumberland area’s cap.

Nearby, the Braves Development Company in August unveiled plans for an Aloft hotel at The Battery. High-end apartment complexes continue to sprout, touting proximity to the stadium’s environs.

And a mile from the ballpark, the Platinum Tower office complex has signed tenants galore—a testament, officials say, to the economic surge the Cumberland district is experiencing.
North America's tallest glass elevator, designed by Solomon Cordwell Buenz, will climb the exterior of the modernist Aon Center skyscraper in Chicago in 60 seconds offering tourists panoramic views.

Local firm Solomon Cordwell Buenz (SCB) has conceived a glass elevator shaft to rise up the northwest corner of the 1,136-feet-high (346-metre-high) Aon Center, leading to a rooftop observatory.

Completely glazed, the elevator will rise up 1,000 feet (305 metres) making it the "tallest elevator of its kind in North America," according to a statement from the firm. The tallest in the world is the 326-metre-high Bailong Elevator, which runs up a cliff in the Wulingyuan area of Zhangjiajie, People's Republic of China.

The shaft along the Aon Center will house a pair of double-deck elevators and will be anchored at every fourth floor. Visitors are expected to scale to the top of the skyscraper in approximately one minute.

The elevator will mark the city's third public observatory, in addition to the Willis Tower Skydeck and The John Hancock Center's 360 Chicago. The latter is similarly thrilling, comprising a moving glass box that tilts visitors over Michigan Avenue.

In SCB's design, the crown of the building is planned as an observation deck with an indoor viewing area offering panoramic views of the city. From here are views of Millennium Park, Lake Michigan and the Loop.

SCB's scheme also includes new building to accompany the skyscraper at 200 East Randolph Street to provide access the elevator and observation area. Located off the street, the low-lying structure will be wrapped in glass and topped with a slanted metal roof.

Inside, it will house ticketing booths, as well as shops.

SCB's ground-level building will continue to allow for Aon Center's lobby to function as-is, exclusively for Aon tenants.

The modern skyscraper – the third tallest building in Chicago – was completed in 1974 by American architect Edward Durell Stone in partnership with Perkins + Will.

Vertical strips stretch to the top and were originally clad in Italian Carrara marble. Stainless steel straps were added to hold the marble in place, and in the 1990s, the entire building was refaced with Mount Airy white granite.

Aon Center was formerly known as Amoco Building, and first served as headquarters for Standard Oil Company of Indiana.

Nina Rundsveen for Moelven
The Council on Tall Buildings and Urban Habitat has dubbed the 85.4-meter Mjøstårnet, in Brumunddal, Norway, as the world's tallest timber building.

At the same time, the group amended the CTBUH height criteria – the official guidelines to measure and rank building height – to recognize timber as a structural material. The update was prompted by the recent uptick of tall timber buildings currently under construction or in planning around the world, and the interest of involved stakeholders and the general public in defining what truly constitutes a “timber” structural system, says CTBUH.

Revised Criteria
According to the revised criteria for timber structures, “both the main vertical/lateral structural elements and the floor spanning system must be constructed from timber." An "all-timber" structure may include the use of localized non-timber connections between timber elements.

A hybrid building of timber construction with a floor system of concrete planks, or concrete slab on top of timber beams, is still considered a timber structure, because the concrete elements are not acting as the primary structure.

Mjøstårnet is located in an area of Norway known for its forestry and wood processing industry. Moelven Limitre, the project’s structural engineer, supplied glue-laminated-timber columns, beams and diagonals, cross-laminated-timber elevator shafts, stairs and floor slabs. Moelven was also responsible for installing the mass timber structure.
Connie Zhou/OTTO
Designed by ZGF Architects with Arup, the striking 48-story tower in Seattle features an innovative diagonal mega-brace system.

Between Amazon’s expanding vertical campus and the in-progress replacement of the Alaskan Way Viaduct with a promising waterfront park, Seattle continues to undergo a rapid transformation. Among downtown’s newest jewels is the Mark, a 48-story hotel and office tower designed by the local office of ZGF Architects that rises from a quadrant of a city block.

The 750,000-square-foot faceted structure rises between two centenarian neighbors, the Beaux-Arts sanctuary of the First United Methodist Church and the Jacobean-style Rainier Club, cantilevering over the former by up to 20 feet. As a part of the project—developed by Kevin Daniels, president of Daniels Real Estate and a member of the National Trust for Historic Preservation board of trustees—the sanctuary was restored for use as an event space.

Constrained to a footprint of just 15,000 square feet, the tower's floor plates had to be extended to achieve the desired square footage. Daniels also tasked ZGF with creating an iconic structure to reflect Seattle’s aspirational spirit.

ZGF used paper models and the classic proportions of the human anatomy to explore dozens of designs that satisfied the constraints. Early concepts featured more “rudimentary” cantilevers or “heavier, more geometric" forms, says ZGF partner Allyn Stellmacher, AIA. “Ultimately, we came back to a disposition of the parts of the building in a way that we thought was more artful, but that also was melded with a more effective [line] for the bracing.”

The final form is an asymmetrical obelisk, with exposed diagonal steel braces that zigzag up each elevation, emphasizing the tower’s verticality. The architects used the long, clean lines of the steel members to differentiate each facet of the façade, whose subtle shifts are enhanced by the reflective glazing. Unlike some exoskeletons, the bracing’s stainless steel cladding recedes 11 inches into the Mark, as if the zigzags are etched into its skin.

The diagonal mega-brace system—among the first of its kind in a seismic zone—derives from ZGF’s close collaboration with Arup, the project’s structural engineer. The tower structure consists of a central concrete core with steel-framed, concrete-infilled floor plates supported by beams spanning up to 50 feet, and four steel columns slightly inset from each building corner on each elevation, leaving the interiors and the corners of the tower column-free.

The perimeter bracing system “acts like a closed tube that engages the axial stiffness and strength of the perimeter steel columns,” according to text supplied by Arup. As a result, it transfers wind and seismic load requirements from the concrete core to the building perimeter, where the diagonal members transfer the loads to the columns. Arup estimates this system uses 10 percent, or 750 tons, less steel than alternative designs.

The 200- to 325-foot-long diagonal braces (inboard of the cladding) consist of approximately 30-foot-long wide flange beams with a depth of 2 feet and flange thickness exceeding 4 inches. At building corners, the X-shaped intersections created where the diagonal braces meet—dubbed “knuckles” by the design team—were among the hardest to detail.

Each shop-fabricated knuckle is uniquely made to accommodate the various incoming angles of the four intersecting diagonal braces, in addition to three floor beams. The brace members were initially bolted to the knuckle during fit up and erection, and then all connections were made permanent via full penetration welds.
Architects' Journal
London’s skyscraper epidemic is spreading with the number of tall buildings set to appear in the capital’s outer boroughs growing by a fifth last year

Research by New London Architecture uncovered a pipeline of 175 towers outside the city centre, each at least 20 storeys tall. This was up 19 per cent from 147 the previous year.

At the end of 2018, the overall pipeline of tall buildings in the capital was 541, with almost one in three located in outer boroughs.

The NLA’s London Tall Buildings Survey found that 60 skyscrapers could be completed this year – more than in the two previous years combined.

‘With more planning approvals in 2018 than 2017 and a slower rate of completions … the total number of tall buildings in the pipeline continues to build up,’ said the study.

‘Tall buildings are taking longer to complete, and this can be for multiple reasons, such as skills shortages, changing project delivery timescales and financial viability issues. In other cases, over-optimistic predictions can play a role in increasing the number of expected completions in a certain year.

‘However, in considering the statistics of the preceding two years, it is conceivable that more than 60 tall buildings could be completed in 2019.’

The number of planning applications for tall buildings in 2018 fell slightly from the previous year, from 78 to 75.

There was an increase in planning permissions with 72 towers granted consent last year compared with 63 in the previous 12 months.

Construction began on 38 tall buildings in 2018, a decrease of two from the previous year. Completion was arrived at on 25, an increase from 18 in 2017.

Almost half the overall tall buildings pipeline was in east London at the end of 2018, although the exact proportion was down from 50 per cent to 48 per cent.

West London saw the biggest growth in share of the pipeline, up from 15 per cent to 17 per cent.

New London Architecture chairman Peter Murray declared 2019 as ‘the year of the tall building’.
2018 CTBUH Tall Building Year in Review
A record demand for tall and supertall buildings appears to be alive and well. But the big question is whether it will stay that way.

The Council on Tall Buildings and Urban Habitat, in its 2018 CTBUH Tall Building Year in Review, found that 18 supertall buildings 300 meters or taller completed construction last year—a record number that beats 2017, but only by three. The number of completed buildings in 2018, at least 200 m and including at least 300-m-plus buildings, is 143. That is four fewer high-rises than in 2017.

The 10-page report, primarily authored by CTBUH's editor Daniel Safarik, is full of data on tall buildings completed and under way. For example, the group predicts between 120 and 150 buildings 200 m or taller to wrap up construction this year.

“This range takes into consideration the total number of projects currently underway, but it is common for a substantial percentage of projects anticipated for completion to be delayed into the next year or later,” says the report.

There are currently 99 buildings 300 m or taller under construction, according to the Skyscraper Center, CTBUH’s interactive database for tall building information. But the report and the Skyscraper Center, which also contains data on proposed buildings, contain no predictions for the number of 2019 construction starts for tall buildings.

“Sites push dirt around for often indeterminable amounts of time before a piece of structure goes into the ground,” which is when CTBUH considers a building under construction, “so our ability to predict true construction starts is hampered,” says Jason Gabel, a spokesman for the group.


Still, there are predictions. Gabel says only Europe and South America will likely not have a supertall building construction start this year. “I would anticipate a slowdown of supertall construction starts in China, but still, the number may outpace the rest of the world,” he says.

The 1-kilometer-tall Jeddah Tower is expected to finish up in 2021, according to the Skyscraper Center. If completed, the building would surpass the current height record holder, the 828-m Burj Khalifa in Dubai, which was completed in 2010. The projected completion of the 644-m Merdeka PNB118 in Kuala Lumpur also is 2021.

In April, the 462-m Lakhta Center is expected to open, making it officially Europe’s tallest. The building in St. Petersburg, Russia, was
Humanity has become obsessed with breaking its limits, creating new records only to break them again and again. In fact, our cities’ skylines have always been defined by those in power during every period in history. At one point churches left their mark, followed by public institutions and in the last few decades, it's commercial skyscrapers that continue to stretch taller and taller.

But when it comes to defining which buildings are the tallest it can get complicated. Do antennas and other gadgets on top of the building count as extra meters? What happens if the last floor is uninhabitable? The Council on Tall Buildings and Urban Habitat (CTBUH) has developed their own system for classifying tall buildings, measuring from the “level of the lowest, significant, open-air, pedestrian entrance to the architectural top of the building, including spires, but not including antennae, signage, flag poles or other functional-technical equipment.” Using this system more than 3,400 buildings have been categorized as over 150 meters tall.

We take a look at world’s 25 tallest buildings, according to the CTBUH, after the break. List updated on January 2019.

25. Al Hamra Tower | 412.6 m | 1,354 ft | 80 floors
Location: Kuwait
Architects: Skidmore, Owings & Merrill LLP (SOM)
Use: Offices
Completed: 2011

24. Princess Tower | 413.4 m | 1,356 ft | 101 floors
Location: Dubai, United Arab Emirates
Architects: Eng. Adnan Saffarini
Use: Residential
Completed: 2012
TMRW, courtesy of Gensler
New York City developer Harry Macklowe and global architecture firm Gensler have proposed a 96-storey office tower in Midtown Manhattan, which could become the city's tallest skyscraper by roof height.

Details of the proposal, named Tower Fifth, were acquired by the New York Times last week when Macklowe submitted the preliminary application to the Department of City Planning.

The developer – who was behind Rafael Viñoly's 432 Park Avenue – has enlisted Gensler to lead the design, while local practice Adamson Associates Architects will serve as the architect of record.

Tower Fifth is intended to be built on a plot along Fifth Avenue, between 51st and 52nd streets.

Designed to reach 1,556 feet (519 metres) tall, it would become the city's tallest skyscraper by roof height. But One World Trade Center, which reaches 1,776 feet (541 metres) to the top of its mast, would still retain the official title.

To build his tower, Macklowe will have to acquire air rights from the surrounding buildings – the majority likely to come from nearby St Patrick's Cathedral.

Renderings of the skyscraper proposal show a glassy, rectangular structure punctured with square windows – almost like a sister to 432 Park Avenue. The exterior will be clad in an "expensive and energy-efficient facade rarely seen in the United States", according to reports.

At the top, the skyscraper would segment into three volumes. The lower block would cantilever out to host "the city's tallest observatory", with access to a corkscrew slide.

This is among a number of features included alongside office space, such as luxury amenities like a pool, a yoga room and a multilevel running track.

Tower Fifth's offices would be elevated above a tall glass lobby, offering views of the cathedral opposite.

Macklowe has already met with New York's Planning Department, the Landmarks Preservation Commission and members of the local community board to discuss the project, according to the New York Times report, to speed up the process of constructing the skyscraper.

Max Touhey
15 Hudson Yards is Diller Scofidio + Renfro’s first residential skyscraper in NYC

The architecture and design firm Diller Scofidio + Renfro isn’t known as a builder of cloud-piercing, skyline-altering towers, but the firm has made its mark on the built environment of New York City in other—and perhaps more significant—ways.

With its work on educational buildings (Columbia University’s new medical school, the Juilliard expansion at Lincoln Center), cultural centers (MoMA’s expansion, redesigning Lincoln Center), and—most famously—the High Line, DS+R’s work is part of the urban fabric, and engaged with on a deeper level than most high-rise buildings.

But the firm is about to make its mark on the skyline, too: 15 Hudson Yards, the megaroject’s 917-foot-tall condo tower, will welcome its first residents soon; the Shed, the cultural center that abuts it, will debut in April. DS+R designed both in collaboration with Rockwell Group, and despite principal Elizabeth Diller’s previously stated disdain for unbridled supertall development—which she told Dezeen “damage the city fabric” in 2016—she’s pleased with the outcome at Hudson Yards. “I’m really very happy to have contributed to New York in different ways,” she says.

Curbed chatted with Diller at a press preview for 15 Hudson Yards; what follows are her thoughts on knitting together disparate building types, working with developers, and why she wouldn’t rule out another skyscraper for the firm.

This interview has been edited for clarity and condensed.

Curbed: I read an interview you did with the Guardian recently, in which you said that you never expected DS+R to work on a large commercial building like 15 Hudson Yards. What made you change your mind?

Elizabeth Diller: We were already working on the Shed at the time for a number of years. The Shed site kept morphing and changing and it was moving west, and we found ourselves adjacent the future residential tower. We were offered the possibility of doing it with David [Rockwell] and first we thought, “This is not what we do. This is not in our wheelhouse.” Then we decided, “Hey we really want a good neighbor. We really want a nice building next to us.”
Adrian Smith + Gordon Gill
Designed by Adrian Smith + Gordon Gill.

Adrian Smith + Gordon Gill have recently unveiled the design for China’s biggest skyscraper and the world’s third tallest once completed, behind SOM’s 828-meter Burj Khalifa in Dubai and the 1,000 meter high Jeddah Tower, which is currently under construction in Saudi Arabia.

Named the Shenzhen-Hong Kong International Center, it will be a 700-meter tall glass tower in Shenzhen, China, set between the foothills of Longcheng Park and Dayun National Park. It will defeat Shanghai Tower, designed by Gensler, which is the current tallest tower in China, with just over 2,000 feet tall.

AS + GG are well known for working on many of the world’s tallest buildings and this one is no exception. The Shenzhen-Hong Kong International Center is tall enough to exceed the supertall tower range (which ranges from 984 feet to 1,969 feet), and will now be considered megatall, whose first member was Burj Khalifa in 2010.

The building shows to be a twisted skyscraper with an anthropomorphic form. It will house one of the world’s highest observation decks, alongside a restaurant, night club, spa facilities and a swimming pool.

The soon-to-become China’s tallest building also holds environmental purposes. Their goal is to obtain LEED Platinum certification, one of the most popular green building certification programs used worldwide.

High-performance glass will be used to reduce heat gain, while the entire development will be orientated to optimize solar gain and natural ventilation.

Also, strategic natural lighting will be used for the interior spaces to increase human comfort levels, and the development was designed so that winds predominantly from the east and northeast are funneled into the open spaces to provide natural ventilation throughout the site and improve outdoor thermal comfort.

A large public transportation centre and bus terminal has also been incorporated by the architects into the tower’s master plan.
The art-deco Chrysler Building in New York City, one of the world's most recognisable skyscrapers, has gone up for sale for an undisclosed price.

Designed by American architect William Van Alen, the Chrysler Building is being sold by current owners Abu Dhabi Investment Council, which purchased the tower in 2008 for $800 million.

The sovereign wealth fund of the United Arab Emirates' government is selling the Midtown Manhattan office building alongside real-estate company Tishman Speyer, as reported by the Wall Street Journal.

Asking price currently unknown

The sale of the historic building will be marketed by commercial real-estate services and investment firm CBRE, which has declined to make the asking price public.

The total figure will be tied to the lease of the land it sits on, at the corner of 42nd Street and Lexington Avenue, which is owned by the Cooper Union. The school raised the annual fee for the site from $7.75 million to $32.5 million in 2017, according to Bloomberg.

The Chrysler Building's future use is currently uncertain. Recent reports suggest that Amazon is nearing a deal to lease a portion of the space, while architecture critic Paul Goldberger suggested that it could be ripe for conversion into residential units.

This approach, he said on Twitter, would be similar to that used at the Woolworth Building in the Financial District, which the Chrysler Building surpassed in height to become the world's tallest (a title it lost shortly afterwards to the Empire State Building).

Goldberger also described the tower as "one of the most glorious pieces of architecture ever created – and still the most beloved skyscraper in New York".

A famous example of art deco architecture

Built between 1928 and 1930 for US car manufacturer Chrysler, the building is most recognisable for its crown, which is clad in Nirosta steel and interspersed with triangular windows.

The tower served as Chrysler's corporate headquarters from 1930 until the mid-1950s, and has many features that hint at this past. These include the bird-shaped gargoyles resembling Chrysler hood ornaments that extend from its corners.