The secret to Glenn Howells Architects’ Bramall Music School’s auditorium acoustics is its low ventilation noise, writes Felix Mara. Photography by Edmund Sumner
It’s hard to say which is the more haunting: Webb & Bell’s Edwardian Chancellor’s Court at Birmingham University, with its Beaux-Arts Byzantiana and eerie Sienese infinity tower; or the nuclear bunker-like silence in the concert hall of the Bramall Music Building, which Glenn Howells Architects has inserted into a mothballed site in the complex.
Although the scale and quality of the court complex, conceived as a hilltop fort and built at the Empire’s heyday, doesn’t appear under-funded, three of the T-shaped blocks planned to radiate from its quadrants were postponed so the Chamberlain Tower could be completed first, and only now has Howells plugged the last remaining gap with the university’s new music department premises.
The Grade II* context was gratefully received by director Glenn Howells. He describes the university’s first chancellor, Joseph Chamberlain, who chose Webb & Bell, as one of the best things that happened to Birmingham. Howells didn’t take the commission lightly. ‘We had to understand the context and develop something that worked on its own terms,’ he says, ‘it was too important for ad hoc decisions and we needed to know when we would and wouldn’t be faithful to the original.’
‘We set out to understand its system to see how rules could be interpreted,’ adds associate William Schofield, who studied sometime orientalist William Lethaby’s Architecture, Mysticism and Myth to try to understand Aston Webb and Ingress Bell’s language of circles, squares, cubes and hemispheres.
There was a tug-of-war between the outside and inside
‘There was a tug-of-war between the outside and inside,’ says Howells. The T-shaped plan form of the neighbouring blocks was unsuitable for the target auditorium capacity of 450, so Howells and consultant Nick Edwards of Acoustic Dimensions developed a carafe-shaped alternative with splayed auditorium walls. These deviate 1.5° from the optimum angle for room acoustics to suit the site layout, which retains access through the ‘fortifications’ to the split-oval court, now passing below a new enclosed annular link between the Bramall and its neighbour. The auditorium, reputedly the most adaptable space of its kind in any British university, accommodates multiple uses, including solo recitals and performances by full symphony orchestras or 200-member choirs. Seating banks, canopy, lift and slide laterally and vertically, modulating volumes and acoustic performance. Absorbent panels tuck into pockets for harder acoustics and double curtains at high level temper amplified sound and balcony fronts are timber.
Source: Edmund Sumner
Acoustic Dimensions achieved extraordinarily low auditorium noise levels. The key to this is extremely low ventilation noise, due partly to below-seat supply air slots without grilles – and therefore without grille noise. The domed rehearsal room was also designed to be flexible. The university’s low sound break-in requirements for the auditorium were relaxed here, allowing large, arched windows. Its 15 x 15m plan is perfect for rehearsals, but the dome was lined with annular slats, reflecting and scattering sound away from its natural focus to arrive at the listener over a 30 millisecond-plus period, rather than simultaneously. These slats run between radial plywood fins defining the dome’s curved surface.
‘Acoustics and domes don’t mix,’ says Schofield. ‘We took a robust details approach, relying on Edwards’ construction knowledge – for example when switching from blockwork to pre-cast auditorium walls, effectively saying: “if you build this, it will perform.”’ With the design team taking the risk, expensive acoustic tests weren’t priced in. Similarly, low auditorium ventilation noise was not specified as the contractor would have charged a high premium to cover the risk of not achieving this.
‘We didn’t want to fudge the maths,’ says Howells. The bays in the auditorium’s splayed walls precisely align with its Edwardian neighbours’ and coursing is finely calibrated. The typical brick module is therefore an unrationalised metric equivalent to its imperial model: 240mm long, 53.5mm high and 110mm thick. The court’s original Accrington red brick was not available, so Howells specified a blend of three Dutch bricks, with an English garden bond variant for the entrance pavilion. Like the originals, this is steel-framed, but has a singlebrick skin.
The site handcraftsmanship of the original buildings was matched by exacting off-site workmanship standards
The site handcraftsmanship of the original buildings was matched by exacting off-site workmanship standards, for example in brickfaced pre-cast auditorium cladding, which was used as the benchmark for hand-laid brickwork. Great care was taken to ensure that the balance in pre-blended batches was not lost when bricks were cut and bonded to these units, but Flemish bonded piers and quarter-running bond panels with chariot-raked mortar joints discreetly distinguish these facades from the originals. Conspicuous mastic joints between panels are avoided by tucking them into internal angles between piers and recessed panels.
The school has twice as many floors as its neighbours and, given the heavyweight services routed through its floor zones and some lengthy spans, you’re never far from a ceiling in some areas. But there are some fine internal spaces and, despite D&B procurement, the construction quality enables the school to square up to its neighbours.
Start on site May 2011
Completion April 2012
Procurement Design and Build
Cost £16 million
Gross internal area 4,800m²
Cost per m² £2,700
Client University of Birmingham
Lead consultant / architect Glenn Howells Architects
Quantity surveyor Faithful & Gould
Structural engineer URS Scott Wilson
Acoustics and theatre consultant Acoustic Dimensions
Services engineer Couch Perry & Wilkes
Fire engineering Arup Fire
Landscape designer Glenn Howells Architects
Interior designer Glenn Howells Architects
Employer’s agent Buro Four
Estimated annual CO2 emissions 35.54 kg/m²
Brickwork manufacturer Daas Baksteen, 40% orange: Tilston NZ055WF, 30% dark red: Rood Onbezand NZ007WF fired in modified process, 30% medium red: Rood Onbezand NZ007WF fired in a modified process
Mortar CPI Euromix cement and sand mix with natural pigment and air entrainer and water retainer admixtures
Precast concrete subcontractor Techcrete
Stone Johnsons Wellfield Quarries, Crosland Hill Hard York Stone
Curtain walling Schüco FW60+, bronze anodized Anolok 545 finish
Windows Schueco AWS 60
Single ply roofing Fatra 810 standing seam zinc cladding to lift overruns and high level auditorium enclosure Rheinzink pre-weathered light grey 0.8mm zinc, standard temper alloy, 600mm spacing
domes and cupola cladding Code 7 Sand cast lead sheet, patination oil applied to underside before installation
Brickwork subcontractor LP Mason