Built 80 years ago on the site of a Victorian playhouse, the Royal Shakespeare Theatre (RST) was considered in the 1930s to be the height of modernity with its cinema styling and Art Deco flourishes. But with a fan shaped proscenium auditorium providing little or no engagement between audience and cast, and outdated access arrangements, it no longer met the increasingly high demands of the discerning theatre going public.
The reconstruction of the RST sees a dramatic change in the audience experience and a return to Shakespearean viewing values with the creation of a horseshoe design thrust stage that ensures no audience member is ever more than 15m from the centre of the action. The new 1100 seat auditorium has the capacity for both over and understage scenery presentation, effectively 7metre objects of scenery can be either raised up onto or drop down onto the stage. Together with a high emphasis on sustainability, energy conservation and additional facilities for both audiences and the general public, the new RST is truly a revolution in theatre and audience space design.
International multidisciplinary engineering consultancy Buro Happold was instrumental in the delivery of this exciting new project from its conception in 2005. Experts in the delivery of buildings for the theatre and performing arts sector, the consultancy worked alongside the client, architects and contractors to create a truly 21st century venue for this Shakespearean namesake.
Comfort is a difficult criteria to quantify; to help to determine how this could be improved in the new auditorium, studies were undertaken prior to refurbishment to establish the existing environment and to gain audience feedback. This resulted in some interesting findings; the audience often perceived comfort in terms of temperature. The studies however showed air quality is the most important factor and that audiences can actually cope with moderate rises in temperature as long as the ‘freshness’ of the space was maintained.
Audience comfort in the new RST will be significantly improved primarily as a direct result of Buro Happold’s design which allows the air supply to the auditorium to be varied in response to the requirements of both audience and actors. The air quality is monitored by sensing devices and will automatically raise the air volume to maintain the “freshness” without adding additional heating and cooling loads.
An immense amount of care went into the planning and execution of the demolition of elements of the old RST to ensure no historical artefacts or features were damaged or destroyed. Buro Happold engineers spent months poring over historic record drawings and investigations within the building to gain a full understanding of how the original building worked.
Detailed methodology was developed to ensure that the retained parts of the building were not damaged during selective demolition, that sufficient bricks were reclaimed for reuse and that the River Avon wasn’t polluted. Buro Happold used highly sensitive tilt meters that fed back wirelessly to a project website to monitor the retained structure during construction. Due to meticulous planning and collaborative working movements of the existing building remained within safe limits, despite vibration caused by heavy demolition and piling machinery operating close by.
The design and construction of the new 8m deep thrust stage basement, enabling large scenery and casts to be concealed beneath the stage, has been one of the principal engineering challenges of this project. While the theatre was still in operation and between shows, the Buro Happold team drilled a 20m investigative borehole below the auditorium to allow samples of the founding rock to be recovered with no visible or detrimental interruptions to performances.
The new basement was constructed entirely below the ground water level. A technique of interlocking reinforced concrete piles with a waterproof lining wall was used to form the basement box. The new basement is now connected to the 1930’s basement on the line of the proscenium after boldly cutting a 6m by 8m opening out of the original basement wall.
The new basement, only meters away from the River Avon, is designed to resist 750 tonnes of uplift from surrounding ground water. The 1.7m thick concrete base-slab and walls of interlocking piles stabilise the area and prevent groundwater pressure from lifting the basement floor.
Above the auditorium, but out of sight of the audience, the new flytower (heaven) is a heavy grillage of structure, supporting over 30 hoists and flying sets, and capable of concealing 25 tonnes of large scenery directly above the stage. The top three levels span 23m across the auditorium, leaving a completely flexible auditorium space beneath. Four large (3.5m deep, 20 tonne) trusses span over the top of the new auditorium to support these colossal loads with less than 15mm deflection. Buro Happold carefully integrated structure with building and theatre services, knitting everything together with supply and extract ductwork, power, audio-visual and stage engineering containment.
The original flytower has been refurbished and strengthened to allow the old counterweight flying system to be replaced with a powered flying system. The old concrete roof has been replaced with a lighter weight steel and timber roof, allowing more of the structural load capacity to be given to supporting theatre services. Large smoke extract fans have been installed in the roof to allow the removal of the old safety curtain.
The future of the theatre in its riverside location relies on an adequate flood defence that will last for the next 100 years. Buro Happold instigated measures to ensure that the design not only compensates for a 1 in 100 year flood scenario, but uses an even more severe benchmark based on the floods of Easter 1998. In order to compensate for the displacement of possible flood waters Buro Happold has incorporated solutions which include planting and flood storage under the new riverside walkway and a new amphitheatre profiled within the landscaping of the Dell area of the Theatre Gardens which would retain excess water in the event of severe flooding and therefore protect the main theatre building. The entrance levels to the new theatre have been set to ensure that a flood would not breach the building.
Inspired by the use of processed timber products in Austrian and other European buildings, through research and design, Buro Happold specified innovative cross laminated timber floors for the main part of the new theatre’s structure.
Using by-products from other timber processes, Alpine builders have employed cross-laminated timber panels as structural and architectural building components for decades.
The UK market however is relatively young. Being a natural material, use of these 250mm thick timber panels had widespread benefits including the absorption of CO2 (a greenhouse gas) and reduced weight-density compared to mineral products.
The decision to use timber flooring instead of concrete was taken by the design team when the project was still on the drawing board. The main advantage is reduced density when compared to concrete floors (almost one fifth) particularly as the supporting capacity of the existing Swan walls is limited.
In the case of the RST new dressing room wing, this reduction in weight meant that an extra storey could be added to the structure. And, of course, the timber option was better value than the equivalent concrete solution as it could be supported by a lighter steel frame and lighter foundations.
These floor panels, akin to “supersized pieces of plywood”, were each custom fabricated in Austria using Computer Aided Manufacture (CAM) processes. KLH (UK) Ltd installed about 630m³ of cross laminated timber for the new theatre, all sustainability harvested from managed European forests and storing a total of 477 tonnes of carbon. This is the equivalent to the carbon emissions from 290 return passenger flights between London and New York.
In terms of carbon reduction the goal for the project was to reduce the building’s carbon footprint by 20%, even though the original theatre was already considered above the good benchmark in these terms. Although this reduction was not linked to any of the project’s funding streams, the RSC, Buro Happold and the other designers felt a responsibility to demonstrate the project’s commitment to future generations.
Understanding how energy is used in theatre buildings is instrumental in developing energy management strategies and efficient systems. This was a key element in the project’s ethos to enable the bold reductions in the overall carbon footprint to be undertaken. To assist in the process Buro Happold carried out a series of benchmarking studies for other venues, establishing when and how they used energy. The results of these studies not only helped to influence the development of the environmental systems but also the physics of the building, leading to a ‘total’ building energy strategy.
Buro Happold provided low energy solutions for the building such as natural ventilation in the large public spaces (for example the foyers and restaurant) resulting in minimal energy usage to maintain comfortable environmental conditions. Other areas that require non passive systems are managed by a control system that maintains the desired environment while operating in an economical manner.
The theatre also makes use of plate heat exchangers located in the air handling systems to recover energy. For example the heat recovered from extracted auditorium air is sufficient to preheat the incoming air to the auditorium (at as low an external temperature of -1ºC) up to audience comfort levels, before the main heating system kicks in.
Lighting was indentified early on by the RSC and Buro Happold as a large source of energy consumption not only in the performance spaces but also in the back of house accommodations. Throughout the development of the design low energy illumination sources such as LED have been specified. Lighting is also automatically controlled to minimise the use of artificial lighting in unoccupied spaces.
The building and its energy generation systems are designed to be future ready; Buro Happold has integrated infrastructure for the future to enable existing and developing technologies to be introduced, to further reduce both the carbon footprint and thus energy use. Indeed major infrastructure has been installed for the future provision of a ground source heat pump system to be introduced into Theatre Gardens.
To ensure delivery to brief, on time and within budget Buro Happold assembled a fully multi-disciplinary team that ‘lived and breathed’ the RST! The whole team, although providing a wide range of services from flood prevention to electrical engineering, had a firm grasp of the overall vision enabling all parties to work together towards a common goal.
The RST is a complex project and building a close relationship with the client was essential to understand both their aspirations and to help them through technical decisions; this was achieved through a site-based team and regular update workshops and presentations.
The geometry of theatre spaces and auditoria is always complex and multi layered, consequently Buro Happold’s use of 3D drawing and coordination methods was critical in understanding how the constituent parts came together. They enabled the consultancy to coordinated simple items such as threading ductwork through the large steel trusses above the auditorium by merging two separate design software packages. This use of 3D drawing and coordination methods also allowed Buro Happold to demonstrate areas of the building to the RSC prior to construction which was particularly important in the existing, retained parts of the building such as the basement plant areas.
Ensuring the safety of both audiences and staff is of the utmost importance in public spaces. Buro Happold’s input went beyond the confines of the more traditional areas of fire detection and suppression to include further elements such as evacuation strategies and the specification of material fire properties. This has allowed the RSC to develop the provision of a total demountable stage and stage house structure without the need for sprinkler protection.
To enable the transformation of the RST, it was essential to find a home for the RSC staff that would displaced by the project. Prior to commencing works on the main RST Buro Happold contributed to the design of a new two storey low energy office building along with refurbished existing building on the Chapel Lane site.
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Buro Happold is a multi-disciplinary international practice of consulting engineers established in 1976. It offers civil and structural engineering, mechanical and electrical engineering, quantity surveying, building services and environmental engineering, health and safety management, infrastructure and traffic engineering, ground engineering, façade engineering, fire engineering, computational fluid dynamics analysis, inclusive design consultancy, project management, urban design and a range of specialist CAD services.