Singapore’s central park

A major mixed-use skyscraper with a difference is approaching completion in Singapore’s central business district – the facades of this richly diverse ‘vertical city’ by Bjarke Ingels Group opens up to reveal generous and highly usable green spaces. James Parker reports

In the heart of Singapore’s financial centre, a new tower is approaching completion which marks a big departure from the norm, by integrating residential, hotel and office space using a capacious, naturally ventilated and green atrium, 17 storeys up. The design for CapitaSpring by BIG (Bjarke Ingels Group) also opens up facade elements to reveal these spaces, delivering a strong contrast with the otherwise strict geometry of the building.

According to Singaporean-American Partner-in-charge from BIG, Brian Yang, the project represents the practice’s maxim of “building things for people and communities, not necessarily for manifestos of our own.” So, while this is a tall building, ranking among the tallest in the CBD at 51 storeys, its unconventional programme and facade design helps the new arrival connect with its surroundings, and the local community.

This is most obviously manifested in how the aluminum fins of the otherwise typical ‘pin striped’ facade bend to offer views in to greenery, and out to the city, as well as fresh air and sunlight. Beginning around 100 metres from the ground, the 30 metre (four storey) atrium contains tropical plants and large trees, and provides a range of naturally ventilated meeting and leisure spaces, connected by a dynamic spiral of circulation ramps.

The 280 metre, 93,000 m2 tower has been jointly designed by CRA (Carlo Ratti Associati) and will be one of the tallest completed in the CBH when the project is handed over – which is due in late 2021. Singapore has a reputation for being a ‘green city,’ with many buildings having “sky terraces,” says Yang. Renders for a new proposal from local firm ADDP Architects’ in the city for example show a pair of 30 storey towers, sporting a large atrium at high level, and copious planting visible from outside.

However, Yang says that BIG’s aspirations were centred around making terraces and communal spaces not only green, but also highly usable. “Sky terraces sometimes end up as empty spaces, not really utilised in a very active way. We want to contribute not only to the aesthetic of the city but also to its social and ecological diversity.”

This led them to seize the opportunity to “transform the use of these spaces in a way that is really impactful and that reveals their fuller potential to a larger public.” It is the project team’s aspiration (shared by the client), that the building will be open to the public, to enable them to experience an unusual new and meaningful green space.

Competition & design process
The developer behind the project is CapitaLand, a Singapore-based real estate giant worth around $5bn and employing over 12 thousand people across Asia. However despite their size, Yang reports that the clients were very accommodating in terms of exploring BIG’s ideas for the project, while having a “very specific brief.” He tells ADF: “Singaporeans are very detail oriented and pragmatic; it was probably one of the best briefs I have ever read.”

The international design competition took place in 2015, with practices including Heatherwick and MVRDV in the running. The project’s construction has been hampered by covid, which impacted heavily on supply chains, but the team reckons it will be completed by the end of 2021.

During the competition, the practice divided the work equally between BIG and CRA, and “collaborated fully,” says Yang, which continued into the detailed design stages, “although over time we also naturally focused on our respective strengths.” Ratti was central to the “digital masterplanning of the user experience,” including how users can interface with the building remotely, such as using an app for access control. The two practices, and client, had “regular design meetings, virtually as well as in person, to ensure things are on track.”

The architects’ proposal was for a steel-concrete composite tower with a single concrete core, containing serviced apartments at lower levels, a central atrium, and offices in levels above. The client initially wanted two towers, being unconvinced they could meet their stringent efficiency requirements using a single lift core for both differing sets of functions.

However, following “a number of engagements” between architect and client throughout the competition, “to their credit, they listened, and opened up,” says Yang. The designers persuaded them that a ‘vertical city’ single tower option, with an integrated garden space, was a valid idea, but the client added a caveat: “Prove it to us you can make it work, and we’ll take a look.”

A further example of how CapitaLand ‘opened up’ was how – via a desire to be a “good citizen, to give back to the community” – they approached opening the Green Oasis as well as retail and F&B to the public. The architect says this commitment is also evidenced by the fact they “have never had a single discussion about cutting the green space out, or downplaying the ambition,” and gives credit to the client for investing in such a generous space with no easily quantifiable return.

The efficiency challenge when stacking the offices above the service apartments in one tower, says Yang, was that the office component would be paying for lifts that also service the hotel floors, and that there was ‘wasted’ space in the atrium, from a planning point of view. So the offices “needed to be that much more efficient to make up for it.” He adds: “It’s not cut and dried that a single tower scheme would be more efficient; it was a rigorous exercise in proving that.”

BIG’s proposal made the most of the constrained, and expensive, site adjacent to Raffles Place, the centre of Singapore’s CBD: “We were trying to make the most compact solution; this was one of the last sites of the historic downtown that was available for development.” He explains further: “The sightlines were very challenging, so there was an entire exercise of being able to clean that up and imagine what a very compact, efficient tower might look like.” As a result of fitting neatly into the plot, and also facilitating the required elevations, the building has a five-faced shape on plan, a truncated square resembling a cut diamond.

The facade is animated, and its otherwise monolithic nature disrupted, by the 6 metre-wide apertures formed by distorting its aluminum vertical fins in three areas to provide porosity – the ground level podium, the atrium, and the roof garden. As the architects say, this creates a “dynamic interplay of orthogonal lines and lush greenery” ranging across the height of the building. Yang adds that it’s “almost a little like a tropical realisation of classic New York modernism.”

The architect calls the project a “reinterpretation of the modernist skyscraper,” with a new take on the ‘live, work, play’ mixed use concept. In itself, the geometry of the tower is relatively strict, and typical floor plates range from 22,200 to 23,300 ft² (2062 m² to 2164 m²). But within those confines, there’s an unusually diverse mix of uses – an “incredible diversity of life,” in the words of Yang.

The 299-unit ‘Citadines’ serviced residence section sits below the atrium, which in turn connects to 635,000 ft² of Grade A office space above. Then there’s a further green “rooftop experience,” with an Urban Farm growing produce for a top floor food and beverage area, including a high-end restaurant. There’s also a Sky Cube events space topping off the building.

The podium contains the entrance atrium and retail, and on its roof sit amenities for residents, including outdoor gardens, a running track, and swimming pools. Levels two and three contain the ‘food centre,’ which conjures up some of the former buzz and atmosphere of the popular Golden Shoe ‘hawker centre’ – the food hall within a 1980s car park which previously occupied the site, selling a wide range of affordable meals to locals.

The office levels have generous 3.2 metre floor to ceiling heights, which should provide pleasant as well as efficient space for anchor tenant, JP Morgan.

Ground level
There was a “holistic agenda between the Urban Redevelopment Authority (URA), us and the client to connect in a very real and public way,” says Yang, “back to Raffles Place and the green lawn space there.” So the building’s ground level was designed to be porous, and “an extension to that park.” A further goal behind this was to connect the building to the now-pedestrianised former ‘Market Street’ that runs alongside.

Another key ground floor element which is part of this connectivity is the City Room, an 18 metre high structure which sits directly outside the main lobby but within the podium, as a “sheltered space dedicated to public use.” Helping provide some shade and comfort in Singapore’s often hot and humid weather, this space provides separate lobbies for the offices and residential units, and leads visitors to the food centre and retail units. The City Room also “opens up into the park,” so that the internal planted ‘rainforest plaza’ connects to the landscape outside, and features a number of “activity pockets” – spaces for fitness sessions, art installations, or other community events.

The Green Oasis
The ‘Green Oasis’ contains four levels of open-air planted walkways, along which sit an open-air gym, yoga space and cafe, as well as event/meeting spaces with kitchens, and space for simply walking and enjoying the fresh air and greenery, or relaxing in hammocks. Workspace is served by ‘ideation pods,’ oval, basket-like metal structures offering a degree of privacy as well as visual connection.

Brian Yang says the space “encompasses the gradient of the programme between live, work and play,” with walkways running from the cafes which are related to the serviced residences below to indoor and outdoor meeting areas – “areas that are connected to working spaces above.”

The Oasis’ interconnected levels are formed by a spiralling “botanical promenade” which creates multiple viewpoints of this “vertical park,” and the city outside. By their nature, the spiral walkways create various voids, allowing the copious amounts of daylight in which is needed for the tropical planting. Trees will be allowed to grow through these apertures up to “anywhere between six and 12 metres,” says the architect.

Yang comments further on the iterative, analytical design approach needed to help ensure this green space was functionally sustainable: “The voids were carefully calibrated to facilitate the maximum amount of daylight to enable the diverse range of plants to be cultivated. It’s not that easy to grow plants 15 metres inside the footprint of a tall tower.” He admits that this aspect of the design “”took a lot of effort, maybe compared to what we were initially expecting.”

In structural terms, the concrete core passes through the atrium, but there are fewer steel columns here than in the levels above and below. So to support the office levels above, a steel truss structure was designed, tying the base back to the core. A similar approach is also used at the top of the serviced residences, at level 16.

Virtual reality came into its own when this space was being designed, says Yang: “When you’re working with experienced people, everybody knows what an efficient office floor design looks like.

But with the kind of green space no-one had seen before, we started doing VR renderings and walkthroughs for the clients.” He adds: “The first time they put the headsets on and experienced the space, the reaction was ‘oh my god, what are we doing!”

In addition to being naturally ventilated, the central atrium and other public spaces receive recycled, cool ‘spill air’ from the air conditioned office spaces to offset heat and humidity; an example of where the architects have tried to use passive design approaches where possible.

There are 77 bike spaces in the basement and 88 on the ground floor, with the client having “a strong desire to promote bike use,” as well as a bike lane planned directly adjacent to the plot, and lockers and changing facilities in the ground floor podium as well as in the basement.

The Partner-in-charge Brian Yang says that in 2019 he was “probably in Singapore nine times, making sure things were going smoothly onsite.” He says it’s been a “big shift” to doing everything virtually, and is keenly looking forward to being able to visit the completed building when safe to do so.

“At least the virtual working was on the later stages,” he says, explaining that BIG had by the stage become “very familiar” with the client and contractor, plus the local delivery architects RSP and “developed a good working relationship. Otherwise it could have been more difficult as it is with anything of such high ambition”.

He concludes that albeit from this remote distance, looking at social media activity, “it feels that people are excited about the building, I can’t wait to actually be there to see it, having had the opportunity to contribute to Singapore’s city building.”