Writing about the redevelopment of central Birmingham in 2008, Stephen Bayley referred to the city engineer, Herbert Manzoni, who strong-armed a brutal post-war urban cast on the city. Manzoni reviled historic architecture and declared that Birmingham had no good buildings. Demolition and newness ruled. ‘Manzoni,’ wrote Bayley, ‘zealously created what is ritually seen as a Godless urban hell, which was obsolete before it was finished.’
In the same Guardian piece, Glenn Howells said the city should not become ‘full of landmarks, but full of dense stuff’. His practice’s Octagon apartment building is the tallest in Birmingham and is claimed to be the world’s first tower with a pure octagonal plan. And so it is, inescapably, a landmark.
But The Octagon is also part of ‘dense stuff’ within the £700 million Argent-then-MEPC Paradise development. It stands on a site at the roughly triangular northern end of the 7ha development on land that rises gently westward from Victoria Square and Hansom & Welch’s 1834 Neoclassical Town Hall. On the other side, medium-rise office buildings have appeared since 2018: three by Howells and one each by Eric Parry and Feilden Clegg Bradley Studios. Three more buildings are in planning or early design stages.
The Octagon’s architecture has a rather mid-century vibe, with faceted elements whose DNA must originate in Harry Seidler’s 1978 MLC Centre (now known as 25 Martin Place) in Sydney, a 67-storey tower with an octagonal plan. Seidler’s façades are distinctly laconic, with chunky corner verticals and weighty horizontal layering.
The Octagon’s lead designer, practice partner Dav Bansal, sought a much more precisely modelled, crystalline demeanour, though that was not part of Howells’ original design proposal. Bansal’s team had been developing a design with a stepped tower connected to another proposed building to the south. But it rankled: a rectilinear plan on a tight, curved site; varying floorplates at greater cost and reduced modular prefabrication; even worse, the building would have presented a blank gable-end to Chamberlain Square.
Then, on Christmas Eve 2019, Bansal realised that an octagonal plan could deliver several key outcomes: optimised prefabrication and logistically efficient erection of structural and functional pod elements; unusually short corridors radiating from central reception spaces on each of the 46 floors above the triple-height multi-use base volume; a compact services zone with lifts, escape stairs and M&E in the space between reception spaces and apartments; maximised glazing and outlooks; and, because of the building’s eight façade facets, reduced wind-loading – something the Victorians understood. The 115m-tall octagonal 900,000-brick chimney built in 16 weeks at William Blinkhorn’s Chemical Works at Bolton in 1843 was one superb formal precursor.
The Octagon’s most notable external design outcomes are precisely the opposite of Seidler’s: the verticals and horizontals are more finely wrought; the fenestration is more obvious and its slim framing emphasises horizontal banding in tandem with the intervening, angularly-faceted aluminium façade panels. Shadow effects vary constantly.
Crucially, Bansal wanted the eight corners of The Octagon to appear as relatively refined vertical edges, rather than brute structure. In short, the façades have an expressive quality. They are also something of a riddle, optically. The bottom folds along the faceted aluminium surfaces project at a relatively tight angle to reduce sunlight into the apartments; the top folds are more open, to maximise views downward. These angle patterns give the fenestration a very slightly curved look in elevation.
There are 16 main structural columns – eight ascending at the outer corners and eight at the intermediate octagonal points. ‘In addition to the eight outer columns on the corners,’ Bansal added, ‘there are two intermediate ones to each facet which align with internal partitions – so 24 columns in total within the 100m perimeter.’
This structural arrangement, by Arup, coupled with precast elements and functional pods prepared offsite by the contractor, JRL Midgard, allowed slightly narrower corner sections and lighter floorplate beams. The contractors ordered the project’s construction materials in December 2021, three months before the Ukraine-triggered cost explosion.
The spatial efficiency – and internal atmospheres – generated by the octagonal plan are interesting. The central apartment lobbies, for example, are low-ceilinged, square spaces with four short radial corridors leading away from the corners. The doors at the corridor-ends, at the halfway radial points in the plan, open into one-bed apartments. Doors on one side of these stubby passages open into full-depth, two-bed apartments and into three-bed variants on the two penthouse floors.
The interior design treatments, led by Howells’ Francesca Ghavami-Milnes, have created decisive and satisfying shifts of atmosphere. In the lobbies, for example, the ceilings are quite low and the colour scheme, essentially dark taupe-brown, produces an interestingly still, faintly mysterious Twilight Zone atmosphere that recalls the sombre interiors in Edward Hopper’s paintings from the 1930s.
Stepping into an apartment, that softly lit compression flips into a lavish spatial expansion dominated by generally pale furnishings and wall-to-wall perimeter glazing. The layouts of the two types of apartments mean that each has a horizontal window measuring 10.8 x 1.45m – 15.5m2 of glazing covering 40 per cent of the entire outward-facing wall. The effect, in the one-bedroomed apartments, is particularly impressive. The trapezoidal plan of the one-bed apartments and the ‘winged’ trapezoids of the larger apartments do not, perhaps surprisingly, create odd pinch-points or dead spaces.
There are two notable glazing details: each glazing cassette, with vent systems hidden above the window headers, has six glass panels divided vertically with five slim black mullions; the lower third is topped with a horizontal glazing bar and bottom-hung, partially opening windows. This glazing ‘split’ emphasises horizontal edges across the façade facets, contrasting with the heft of the corner verticals; it also gives the glazing a more domestic feel. The height of the lower glazing bar was carefully considered in relation to outward views from seated positions.
The design of The Octagon highlights two fundamental advantages over orthogonal equivalents. Compared with a rectangular building with a comparable perimeter and volume, The Octagon has 1,000m2 less surface to the elevations. And, during the design process, the embodied carbon in the building’s shell and core was forecast to be 516 kgCO₂e/m2 – well below CABE’s benchmark level for residential developments at that time. Howells plans to produce an in-use carbon assessment in due course.
I can offer only one architectural reservation, concerning the pleated aluminium folds of The Octagon’s plant-concealing crown. If considered in relation to the angular play of the white, mica-flecked anodised façade panels and corner verticals, could these finessed pleats have been more boldly articulated to emphasise the inherent elegance of the crown’s surfaces and their effects of light and shade?
Nevertheless, The Octagon has given the very obviously design-led Paradise tableau, and Birmingham, an architecturally successful high-point that is emphatically not, as Stephen Bayley said of Manzoni’s urban sledge-hammering, obsolete before it was finished. Bansal’s team is currently completing the design of scalloped-brick façades for a hotel at the south end of the Paradise development which will, unlike the Blinkhorn Chemical Works chimney, take more than 16 weeks to build.
Jay Merrick is an architecture critic and author
Architect’s view
Developed for a spatially constrained city-centre site, the geometry of the world’s first pure octagonal high-rise residential tower emerged from the challenges of the site and a search for greater efficiency.
The octagonal plan reduces façade area by approximately 15 per cent compared with a conventional residential tower. This lowers embodied carbon through the reduction in material use while improving thermal performance through its more compact form.
A centralised core with reduced wind loads, radial structure and shorter service runs further reduces material consumption and increases construction efficiency. The apartments exceed national space standards by as much as 10 per cent. The Octagon is an exercise in ‘less is more’: a building where simplicity of form delivers environmental, structural and spatial benefits simultaneously.
A fabric-first approach underpins the environmental strategy. Carefully controlled glazing and a deeply modelled façade balance daylight, views and solar performance, while every apartment occupies a full facet of the octagon, maximising natural light, supporting natural ventilation and offering generous panoramic views.
The project adopted a Design for Manufacturing and Assembly (DfMA) approach throughout. An aluminium façade system with elements manufactured off-site and assembled on site, together with precast structure and prefabricated bathroom and utility pods, improved quality, reduced waste and accelerated construction.
Extensive prototyping and testing informed the façade design, ensuring precision, durability, performance and ease of maintenance over the building’s lifespan.
As part of the wider Paradise masterplan, The Octagon delivers 370 homes, supporting Birmingham’s ambition for a more diverse and mixed-use city core. The project demonstrates how architectural innovation, construction efficiency and environmental performance can be brought together through a single, coherent idea.
Dav Bansal, partner, Howells
Client’s view
The Octagon’s design references the city’s industrial heritage and the nearby Jewellery Quarter, while sustainability was a key driver from first principles.
Leading on Modern Methods of Construction (MMC), the design and construction team constantly looked at ways of reducing carbon footprint by minimising material wastage and improving site safety.
This included modular construction for the façade, internal units such as bathrooms, kitchens and apartment utility cupboards, plus the heating and electrical systems.
The use of precast walls, slabs and columns throughout the building, and preformed wiring looms and pipework, also contributed to reducing the carbon footprint.
All deliveries were sourced locally, over the shortest distances. For example, all precast concrete components were manufactured in the Midlands and brought to site as required. High levels of material recycling, whether from earthworks, concrete or steelwork, coupled with minimal waste to landfill, ensured that 100 per cent of material was re-used on site.
Operational efficiency is reflected in the building’s design, with expansive windows, significantly reducing residents’ reliance on artificial lighting and ventilation, while taking advantage of the panoramic views.
The building also features a UK-first pressurised core and exceeds new cladding and material standards introduced following the Grenfell disaster.
The project respected local communities with a more than £50 million local supply chain spend, supporting jobs in Birmingham, while added social value included 237 apprenticeship weeks, engagement with 100 students, 390 volunteering hours and generous donations to local charities.
Andy Bushell, senior development manager, MEPC (owned by Federated Hermes Real Estate)
Engineer’s view
By responding directly to MMC, sustainability and global concerns with the carbon load of the built environment, The Octagon became a leaner, cleaner and simpler design by working in collaboration with the wider design and delivery team.
SOM Structural Engineers carried out several time and material saving optimisations of the original design as well as helping to maximise the deployment of site labour.
Working closely with the lead architects, Howells, SOM’s solutions directly addressed the requirements of the project but also the unique opportunities presented by the site and design.
The Octagon’s façade was prefabricated offsite, while, in contrast to traditional slab construction, lattice plank construction was used for all floors. The unique layout of the building allowed for a highly repeatable grid, with the lattice planks acting as permanent formwork, creating a quickly installed and safe working environment.
Along with the elimination of conventional formwork and labour, this system allowed for a dramatic reduction in transport movements to and from the site and reduced noise pollution.
Virtually all the materials for the core and columns were precast, arriving at site just in time, helping to manage labour and stabilising programme disruption, as well as improving the end-quality.
Stuart Marsh, senior associate principal, Skidmore, Owings & Merrill (SOM)
Working detail
The façade detail reflects the core ambition of The Octagon: to create a building that achieves more with less. Utilising Design for Manufacturing and Assembly (DfMA) methodology, the façade was conceived as a prefabricated kit of parts that could achieve utmost quality, minimise waste and accelerate construction.
From the outset, we understood that the façade would be a prefabricated wall system, in common with most tall buildings. However, these systems can appear flat and relentless, especially in a regional economic context. In contrast, The Octagon’s striking feature is its deeply sculpted, dynamic façade that changes with sunlight and the pure octagonal geometry of the tower was instrumental in this approach.
With eight identical elevations repeated around the building, components could be standardised and manufactured offsite with a high degree of precision. Façade panels were prefabricated, pre-glazed and quality-checked before being transported to site, where they were assembled and installed efficiently. This process reduced material waste, improved workmanship and minimised time spent working at height.
Material selection was guided by performance, durability and appearance. Lightweight aluminium reduced structural loads while offering excellent longevity and resistance to weathering. Working with our façade subcontractor, McMullen Façades, we folded continuous sheets of aluminium into rigid box sections, designed so that no additional internal structure was required, as well as avoiding any continuous cavities.
The angular panels are finished with a bespoke two-tone, polyester powder coating developed for The Octagon by AkzoNobel, containing small gold mica particles on a white base that responds to changing daylight conditions and shifts in character from dawn to dusk.
David Sharpe, associate, Howells
Project data
Location: 1 Great Charles Street Queensway, Birmingham B3
Start on site: November 2022
Completion: August 2025
Gross internal floor area: 32,900m2
Construction cost: £84 million
Construction cost per m2: £2,553
Architect: Howells
Client: MEPC
Structural engineer: SOM
M&E consultant: Design MEP
Quantity surveyor: Quantem
Project manager: Quantem
Principal designer: Stephen Barnsley Associates
Façade consultant: Wintech
Interiors: Howells
Acoustic consultant: Cass Allen
Wind and sustainability consultant: Arup
Fire consultant: Turley
Utilities consultant: Gattica Associates
Approved building inspector: Acivico
Main contractor: Midgard
CAD software used: Revit
Sustainability data
Percentage of floor area with daylight factor >2%: Not calculated
Percentage of floor area with daylight factor >5%: Not calculated
On-site energy generation: Nil
Heating and hot water load (amenity): 17.48 kWh/m2/yr (predicted)
Heating and hot water load (residential): 17.2 kWh/m2/yr (predicted)
Operational energy (amenity): 47.05 kWh/m2/yr (predicted)
Operational energy (residential): 65 kWh/m2/yr (predicted)
Total energy load (blended): 63.9 kWh/m2/yr (predicted)
Carbon emissions (all): 19.02 kgCO2/m2 (predicted)
Annual mains water consumption: 40.1 m3/occupant (predicted)
Airtightness at 50Pa: 1.5-3 m3/hr/m2 (predicted)
Overall thermal bridging heat transfer coefficient (Y-value): 0.029 W/m2K (predicted)
Overall area-weighted U-value: Not calculated
Annual CO2 emissions: 19.02 kgCO2/m2 (predicted)
Embodied carbon: 685 kgCO2eq/m2 (predicted)
Whole-life carbon: Not calculated
Predicted design life: 60 Years
Energy Performance Certificate rating: B