CASE STUDY THEATRE ROYAL GLASGOW SCENE STEALER A psychedelic, swirling lobby stars in an extension to the Theatre Royal, Glasgow, and is central to the buildings ventilation strategy. Andy Pearson went backstage to find out how Max Fordham updated a Victorian classic The foyers golden faade is in stunning contrast to the original theatre building T IMAGES ANDREW LEE UNLESS OTHERWISE STATED he Theatre Royal, Glasgow, was ripe for refurbishment. Built in 1867, it was designed with separate entrances for the hoi polloi and the more well-todo, with those in the cheap seats forced to make their way to the auditorium through various side entrances and back passages. More than a century later, nothing had changed. Without passenger lifts, almost all audience seating was inaccessible to wheelchair users. Foyer space was limited and the bars were too small to service Glasgows thirsty theatregoers. Once inside the auditorium, the audience had to put up with a stuffy and, often, uncomfortably hot environment. In 2008, Scottish Opera which had bought the building in 1974 set out to tackle the theatres shortcomings, and acquired a plot of land adjacent to it. The following year, the company launched an architectural competition to design a 11.5m entrance pavilion that would improve accessibility and provide a new box office, foyers, bars and toilet facilities. Importantly, the winning entry would also have to greatly foyer, so we knew we would have to move the boiler room, the main air handling plant, electrical switchgear and the gas meters. The first thing the Max Fordham team did was to establish which services were installed, how they functioned and where they were enhance the audiences journey from street to seat. Local architect Page\Park won the competition with its proposal for a golden, drum-shaped entrance, featuring at its heart a sweeping double-helix staircase to provide a dramatic and egalitarian route to the auditorium. The scheme included lifts that ensured step-free access to all four levels of the theatre, while cafs, bars and a roof terrace all added to the visitors experience. In 2010, Scottish Opera appointed engineers Max Fordham to the team, to develop a low energy building services solution for the extension and devise a way to improve comfort conditions in the auditorium. This was all well and good except the client needed the theatre to continue putting on productions throughout the improvement works. Crucially, its existing plantroom was on the site where the new entrance pavilion was to be constructed, and had to be demolished before work could get under way. Mark Palmer, senior partner at Max Fordham, explains: The existing plantroom was located slap-bang where we wanted to build the new eOR RMadE PROJECT TEAM A chimney carries warmed air through the core of the drum and out through high level openings PROJECT TEAM Client: Scottish Opera Architect: Page\Park Building services engineer: MaxFordham Cost consultants: Capita Main contractor: Sir Robert McAlpine M&E contractor: Vaughan Engineering Improving comfort in the auditorium was key routed around the old theatre, so that it could start to develop a means of maintaining them during the works. The subsequent investigation involved examination of record drawings, as well as extensive site surveys of the building and the category-A listed auditorium. The engineer also took the opportunity to study CO2 levels and temperatures in the auditorium during performances, to identify comfort issues and to establish where improvements were needed. Quite a lot of investigation had to be done to understand how the building was working, where the existing distribution routes ran and where it was possible to add new routes, says Palmer. At the same time, Max Fordham was developing a building services strategy for the new extension. Originally, it was proposed that the pavilion would be serviced independently of the theatre. After exploring the different options, however, it became apparent that it would be better to integrate the foyer services including life safety with the existing systems, As soon as you start to look at these things, you realise it doesnt make sense from a building services point of view to have separate plant in the foyer that doesnt interface with the rest of the building, saysPalmer. This meant the new plantroom would need to service both the existing theatre and the new foyer but where could it go on the confined site? The solution was stumbled upon after discussions with the fire engineer, when it became apparent that the vastly improved access created by the swanky extension would make one of the theatres fireescape staircases redundant. The engineers realised that by removing the stairs from the stairwell and casting new floor slabs at each level, they would be able to develop this space as a vertical, five-storey plantroom and main distribution riser. The new plant space in the existing building provided an ideal access to all levels and avoided the need for costly, temporary services installations it was a stroke of luck, admits Palmer. Because it was in the existing theatre, the found space had the additional advantage that it could The foyers staircase helps draw warm air away serve as both an interim plantroom during the foyers construction and, later, as the final plantroom. As soon as the new floors were constructed, new plant including switchgear and boilers were installed, commissioned and connected to the existing systems to enable the auditorium to function while construction of the foyer went ahead. The converted staircase allowed us to build the permanent plantroom in the existing building, before we started work on the foyer, explains Palmer. The old circuits and new plant were kept separate as far as practical. For example, plate heat exchangers were installed between the new boilers and the retained low temperature hot water (LTHW) circuits so that, should a problem occur with the ageing existing system, it could not be attributed to the new works. We made sure there was a clear interface between the new and the old, says Palmer. The one major item of plant that could not be installed was a new auditorium air handling unit (AHU), A redundant stairwell served as an interim plantroom while the foyer was being built Balcony level Education level Upper circle level Dress circle level CREDIT: VAUGHAN ENGINEERING Stalls mezzanine level Stalls level because it was to be located on the roof of the, as yet unbuilt, new foyer. As an interim solution, the auditorium air distribution ducts were kept supplied with 12m3/s of fresh air by a fan and heater battery temporarily located on the roof of the existing theatre. One of the biggest challenges in developing the services strategy was devising a solution for what Palmer describes as the new foyers peaky occupancy pattern, when 1,400 theatre-goers gather in its bars before the show and during the intervals. Max Fordhams strategy has been to keep the solution as simple as possible, with natural ventilation and a responsive heating system. Natural ventilation provides free cooling and fresh air, and the heating responds as soon as the temperature starts to rise, says Palmer. The occupancy is so peaky and short-lived that, if mechanical ventilation was used, you would end up putting in some very big plant that would spend most of its life switched off. Air is drawn into the space at each floor level from perimeter vents concealed in the faades protruding gold fins. The theatre is next to a busy main road, so to prevent traffic noise entering the space and to minimise breakout noise the vents open onto an acoustically attenuated air duct, concealed within the foyer furniture. The duct directs the fresh air to highlevel openings within the furniture. A motorised volume control damper, under the control of the BMS, regulates the quantity of air admitted to the space in response to internal temperature and CO2 levels. This natural ventilation solution is helped by the foyers spiral staircase. It acts as a chimney to carry warmed air up through the buildings core and out through openings in the highlevel lantern light at the top of the extension. The same ventilation strategy is used for smoke ventilation in the event of a fire. An LTHW fan convector unit, concealed at low level in each wall unit, provides heat to the space. There are 12 bays on every floor, each of which has a bespoke joinery cabinet with integrated heating and natural ventilation ducts and grilles, plus power and data connections for public use. Services to the bays are distributed at high level on each floor, concealed behind two concentric timber rings that form a feature of the ceiling. The outer ring carries the main services, while the inner ring houses an extensive architectural lighting installation. The rings appear unconnected, to keep the coffered concrete soffit clear of cabling. To maintain this separation, two steel conduits were cast into the slab of the floor above, to carry the wiring. The foyer has no mechanical cooling; instead, the design relies on the thermal mass of the pavilions concrete frame and floor slabs to limit sudden temperature rises when occupancy levels jump up during show intervals. It is a large, heavyweight space and it can absorb these occupancy peaks to maintain comfort with minimal mechanical intervention and, therefore, minimal energy consumption, says Palmer. When construction of the new entrance was complete, the new auditorium AHU was installed on its roof. To help improve comfort levels, the air handling unit is coupled with a chiller and a heat-recovery system to improve air quality and energy efficiency in the auditorium, without changing the look of the space. We had to stick with the existing auditorium air distribution system, which supplies fresh air through a series of vents oneach floor, says Palmer. This could have created pockets of stratified air; however, by installing a new extract system, we were able to improve the air distribution. Palmer says early feedback from theatre-goers and staff suggests the solution is working well. The acid test will come, however, when Max Fordham obtains the first years energy use figures and monitoring results, to see how the conditions in the auditorium now compare with conditions prerefurbishment. CJ