In the first of a series of case studies on the way architects incorporate research into practice, Kat Martindale explores how Tonkin Liu uses physical model making and digital modelling analysis to inform its built work.

Photos
David Valinsky

Model making forms an integral part of Tonkin Liu’s research and design process. From the plasticine, paper and card employed from the start of the design process to the exhibition models showcased at high-profile London galleries, models are retained as a record of its process. One of the largest models in the studio is that of the Tower of Light, which formed part of the Aram Gallery’s 2018 Architecture Prototypes & Experiments exhibition, and was also displayed at the Royal Academy’s Summer Exhibition in the same year.

Civic ambition

The Tower of Light is the first part of Vital Energi’s Civic Quarter Heat Network and energy centre in the Deansgate area of Manchester. The Tower provides the structural support to five flues, while the pavilion, incorporating the Wall of Energy, houses the engine and boilers that will serve eight buildings across a two kilometre network, including the town hall, central library, and convention centre. The scheme will reduce carbon emissions by 1,600 tonnes annually, representing an efficiency of 45 per cent and supporting the city’s ambition of achieving zero carbon by 2038.

Clients Manchester City Council and Vital Energi wanted something that the practice hadn’t designed before. To do ‘something we’ve never done before’ is a concept that is central to the ethos of the practice and is included in its entry in the RIBA Directory. However, with any research, one project builds on the knowledge and methods developed previously. The Tower of Light builds on the almost 15 years of research and development for which the practice has previously won funding from Innovate UK and was awarded the 2013-2014 RIBA Research Trust Grant.

The point where the graduated, undulating high-gloss tiles of the Wall of Energy give way to the vertical steel tower structure.

While each project is approached differently, the practice repeatedly returns to the biomimetic shell lace structures for which it is best known. Mike Tonkin considers the design for the Solar Gate in Hull, completed in 2017, the forerunner to this project: “Without the Solar Gate, there would have been no Tower of Light.” Although at ten metres tall it is one quarter the height of the Manchester tower, it further developed the production process and steel structure, as well as included apertures within the lacework.

Compared to the poetry of the Solar Gate – a form of sundial marking out key moments of the city’s history – the Tower of Light is more pragmatic, offering structural support to five chimneys. The research behind the design proposal aimed to combine energy, nature, and culture, while also drawing inspiration from the man-made: the turning Tudor brick chimneys of Hampton Court Palace; and from nature: the Cholla desert cactus. Rejecting the usual premise that would have suggested building a support between the five flues reinforced with bracing, external fins and a decorative cladding, the practice has wrapped the flues in a structure that is also the artwork.

The lighting design for both the Tower of Light and Wall of Energy highlight their forms, while the lights of passing traffic are reflected in the Wall’s tiles.

A diagram of forces

The models created through the early phases of design development are produced by all members of the team, including long-time collaborator Ed Clark, a Director at Arup. Having first worked together on the Bexhill Pavilion competition entry in 2009, the established partnership allows for a continuous flow of ideas, with each new project building upon the last, further evolving knowledge and structural forms. The models and drawings developed in the practice studio are followed by rigorous analysis at Arup using parametric software. This tests the stability of the structure, particularly under wind loading, and the weight of the tower itself, as well as refining the lace pattern, the frequency, location and sizes of the apertures, and the thickness of the steel and cutting patterns to recycle cut-outs and minimise waste.

Citing the Scottish mathematical biologist D’Arcy Thompson – “the form of an object is a diagram of forces” – Tonkin discusses the form of the structure, expanding on the need to address the site constraints and prevailing winds that define its oval profile. Steel sheets, 8mm thick at the base and 6mm thick further up, were laser-cut before being rolled and then welded together at a 90 degree angle informed by the structure of shell walls.

The tower comprises ten oval drums four-metres tall, three-metres wide and six-metres in length, produced by local steel fabricator Shawton Engineering and designed to fit within a standard flat-bed lorry. The undulations in the form strengthen the structure, allowing for thinner steel than a smooth cylinder, and avoiding the need for additional bracing.

Aside from their structural and decorative functions, the perforations also expose the polished surfaces of the flues and the petal-shaped, gold-finished stainless-steel reflectors bouncing light around the interior of the structure. At night, the tower is illuminated by LED lights designed by SEAM Design, that change every 15 minutes and come with a control system that allows the City Council to select from a range of themed designs to mark specific events, such as Pride, or emblazoned red or blue to acknowledge the city’s football teams. These effects are coordinated with the lighting for the pavilion at the base of the tower.

Reflecting the city

Clad in 1,373 white high-gloss, hand-finished tiles, the 65-metre long Wall of Energy stands at six metres before dipping under the bridge that carries the tram into the city. In its earliest proposal Tonkin Liu specified flat tiles across the pavilion’s façade, but this was rejected by the client in favour of something more dynamic. Returning to its original three-part concept for the centre of energy, nature, and culture, the practice focussed on translating energy and its capture from natural resources, investigating the impact of wind, solar and wave actions on the environment.

The final design for the tiles follows the shapes left by wave action on the seabed. Using a 3D digital model, Darwen Terracotta produced full-scale prototype CNC-cut foam models of each of the 31 differently-shaped tiles to produce a range of negative molds that could each be used to produce twenty tiles before being re-formed. The re-forming and reshaping allowed for gradual changes in the shape of the tiles (a prototype tile was included in the postponed 2020 Royal Academy Summer Exhibition).

The tile design across the wall starts with flat tiles at ground level with a ripple that develops upward and across the façade as the shape and volume of the tiles grow. During the day, the high-gloss tiles reflect the clouds, replicating the movement of water over the sand that inspired their form. At night, they reflect passing vehicle lights.

A long window pierces the tiled façade, providing a view into The Energy Centre. Inspired by the Hacienda night club and the colours used in electrical wiring panels, the interior invites passersby to peer in and observe the 3.3MWe CHP engine and two 12MW gas boilers that distribute across the two kilometre network. The aim is to engage an ongoing city-wide conversation about alternative energy sources and to demonstrate Manchester’s commitment to advancing knowledge and debate.

This beautiful, awe inspiring, engaging and multi-layered response to the project brief is the result of Tonkin Liu’s research-led design approach, ongoing research partnership with Arup and collaborations with specialist producers and evidence of what can be achieved when creativity and poetry coexist with pragmatism and rigourous research.

Additional Drawings

Credits