In a busy, Scottish city-centre theatre, conditioning the temperature as well as the sound – discreetly – is critical
Speaking of Page\Park’s newly completed £10m extension to Charles Phipps’ 1867 Theatre Royal Glasgow, project architect Jamie Hamilton says that when the firm won the OJEU-run competition in 2011 against Nord, Caruso St John, Terry Pawson and Tim Ronalds Architects, the design was rather different to how it is now.
‘The competition scheme was different in concept,’ explains Hamilton. ‘We emphasised the horizontal articulation, in principle to help the building turn the corner, but as the services strategy evolved during design development the emphasis moved to the vertical’. Whatever the post-win shift, Page\Park’s bold and brassy new elliptical foyer space, designed to feed the refurbished Category A listed auditorium on four levels, still makes an event of the turn of Hope St into Cowcaddens St in the centre of the city. In doing so, the deeply articulated facade, formed of insulated steel ducts, becomes a physical manifestation of the air handling in a similar vein to Franco Albini at his seminal 1960 Rinascente in Rome – but here it’s naturally ventilated.
Hamilton says that although the design of the foyer facade was inspired by the dramatic baroque balconies of 19th century auditoria and the staccato nature of a musical score, it was only after services engineer Max Fordham was appointed that the formal inspiration began morphing into a more technical approach.
Internally, the programme remained the same, with the architect keen to emphasise the audience’s journey from ‘street to seat’, providing full access to the 1400-seat theatre and fulfilling the client’s desire to ‘open up’ the venue with a multi-use public foyer space. Linking all these levels is a grand staircase, as baroque in intent as the original theatre, but utterly contemporary in appearance.
While there’s a lot of low-e glass evident on the facade, giving great views over the city for the foyer’s users (although it accounts for only 40% of the total surface area) Hamilton explains that it’s the externally expressed gold stainless steel air intake ducts that do the lion’s share of the work; facing north west, the glass, deep set relative to them, is shaded from residual solar gain. Behind the ducts meanwhile is the ellipse of 1250mm by 300mm concrete piers defining the foyer space and supporting its 150mm thick concrete floors. With all that concrete you’d think there was a thermal mass strategy, but Mark Palmer, senior partner at Max Fordham, says that’s a bit of a red herring. ‘It doesn’t generally work for the typology. Here large numbers of people generate heat in short bursts, which required robust approaches to conditioning the space,’ he says. He adds that the firm’s many thermal models recommended responsive ventilation – hence the vertical ducts – so the building can be cooled during use and closed down to conserve heat while it is empty.
Installed in every second fin, the vertical insulated risers running up the facade provide a direct path for external air to pass into the duct where the frontage recesses at ground floor, and to be channelled via motorised dampers into the building. This air is fed into the space at each level via the alcove created between the concrete piers from behind bespoke birch ply panel joinery, forming the ellipse’s inside face. ‘There are convector heaters behind the birch ply bay grilles whose air mixes with the cold high-level incoming air a few feet above it, pre-heating and tempering it as it enters,’ says Palmer.
Hamilton explains that Kingspan rigid thermal insulation on the inside face of the ducts is there to keep it as close to the glass line as possible. Acoustic insulation lines the ducts, ensuring that noise from the busy city street (it’s a major bus route) does not break into the foyer space. As it was, there was a demand for the glazing envelope and cladding to offer 33dB sound reductions across the facade. Hamilton adds that the acoustic attenuation within the fins is in the order of 10dB.
‘It’s all been efficiently integrated into the vertical duct element. Hidden behind the panel you can’t see any heaters, dampers or louvres – it’s all very neat,’ he says.
There are external benefits too: the ducts act as solar shading, to deal with the worst effects of solar gain from west light.
Branching off the concrete piers, each with its own unique geometry according to its position in the ellipse, radial trusses lead back to a chunky 1250mm by 1250mm concrete ring beam. This forms the base of the foyer structure’s lantern and acts as the hanging point for the dramatic staircase. Hamilton says the necessary stiffness was achieved by making the stair strings from rectangular hollow sections, with each birch timber balustrade acting as a form of truss between floors. Timber acts acoustically here as well as structurally. With Jura limestone on the floors and concrete predominating, Page\Park needed to cut reverberation times.
‘We wanted to take the edge off the hard finishes,’ says Hamilton, ‘so we augmented the timber of the stair using Bute fabric with acoustic foam behind it in the soffit.’
A timber ring of lighting, fire detectors, alarms and PA systems running around every ceiling, plus fabric panels with acoustic foam behind them, further reduce reverb times on all levels. Scottish Opera’s own team of carpenters performed the expert joinery. Meanwhile, at the top of it all the lantern is part of the ventilation strategy and acts as a fire reservoir, with actuators opening to allow exhaust air (or smoke) out at high level if needed. Heat exchangers were initially considered here but, given the building’s intermittent use, could not be justified.
Despite its novel approach to ventilating the foyer space, it seems the system is working well; Mark Palmer notes that contrary to most passive ventilation systems that end up overridden by users, the facilities team likes the heating and damper ventilation system. ‘Because old theatres don’t tend to have good ventilation, theatre staff are instinctively attuned to anticipating what the heating or cooling demand might be and planning for it,’ he says, and they’ve taken to the system like ducks to water. The vent ducts also deal with the number of openings that natural ventilation strategies usually demand, which affects U-values. ‘There have been a lot of advantages to separating the lighting element from the natural ventilation,’ he notes. ‘You can install blinds for instance and the ventilation still works perfectly.’ And for a space whose potential as a theatrical event in itself rather than the prelude to one is only now being realised, Palmer thinks that eventuality is being given serious consideration. ‘Because when you walk in it’s an incredible space; far more than the client – indeed anyone – imagined.’
Architect Page \ Park Architects
Client Scottish Opera
Structural engineer Arup Scotland
M&E consultant Max Fordham (including lighting design)
Quantity surveyor Capita
Project manager tX-2
CDM co-ordinator CDM Scotland
Main contractor Sir Robert McAlpine
Acoustics Sandy Brown Associates
Fire engineer Atelier 10
Access consultant Adapt