The Building Conservation Directory 2022

PROFESS IONAL SERVI CES 1 15 C AT H E D R A L C O MM U N I C AT I O N S T H E B U I L D I N G C O N S E R VAT I O N D I R E C T O R Y 2 0 2 2 many venues would heat a vast space for just a few technical crew, many hours before the public arrived. At its simplest, improvements can be clearly communicated instructions on how to minimise waste like this. At a more technical level, managing heating, ventilation and lighting can be operated automatically using motion sensors, timers and air quality monitors that turn off or turn down services when an area is not fully occupied. The use of these sensors is normal practice in new development, but they work equally well when installed in historic buildings. At a more complex level, services can be programmed using a building management system (BMS) and managed using software. In practice, a BMS can be complex and there is a risk of a building owner being unable to fully operate the software and reverting to on/off switches. It is therefore important that the system is designed to suit the operator’s skill level. INSULATION In contrast, one of the most difficult issues faced when upgrading is the improvement of levels of insulation. Typically, historic theatres and cinemas have a basic structure that is poorly insulated, including masonry walls with no cavity and single glazed windows. There are good alternatives to the steel-framed ‘Crittall’ type of window widely used in the early 20th century. New steel windows with double-glazing units and thermally broken frames can match existing fenestration patterns and may not greatly alter the appearance of the building. Secondary glazing can also be a good solution, particularly if the building is listed, as it retains original features and the appearance of a façade, while improving thermal performance and acoustic separation within. The improvement of wall insulation is a more difficult challenge. Although it is possible to add insulation to the inside of a wall, there is a limit to how much can be added before the inside face of the masonry wall becomes too cold and attracts condensation. Adding wall insulation to the outside of walls is not an easy solution either given this means change to the external appearance. Architectural practice Foster Wilson Size is currently working on a project to refurbish a performance venue dating from the 1930s to achieve Passivhaus standards. The only viable way to do so is by introducing external wall insulation, which is to be clad in brick slips that mimic the existing brickwork and replicate the current appearance, albeit with thicker walls. In most cases this strategy might have more relevance in improving the insulation of the side walls of a theatre, which can be very utilitarian in comparison to the front façade. Leaving a front façade intact while improving the insulation of side walls can still bring major benefits to overcoming heat loss. VENTILATION AND COOLING Ventilation has understandably received a lot of attention recently. It is clearly very important to ensure that an audience receives plenty of fresh air, but the ventilation and cooling systems are often the biggest consumers of power. It is possible to achieve natural ventilation and cooling in the design of a new auditorium. For the new performing arts space at Cheltenham Ladies College, Foster Wilson Size used an under-croft below the new auditoria to moderate the temperature of air which is brought in below the seating close to the audience, before being released as warmer air at the top of the auditoria by a chimney stack effect. Although it is very difficult to retrofit an existing auditorium designed exclusively for mechanical ventilation, older theatres of the Victorian period that predate the widespread use of this method were originally designed with ingenious methods of ventilation that can offer clues for current improvement. Victorians understood the basic laws of thermodynamics and used the release of hot air to draw fresh air in at the base of an auditoria. One of the most popular ventilation methods for 19th century theatres was the use of Sunburners, a ventilation and lighting installation powered by gas jets, providing both light and the heat source for a chimney stack effect stale air extract. During the restoration of Hoxton Hall, a beautiful music hall of the 1860s, the ventilation system was able to use the position of the original Sunburners as these were already located in the best place to expel hot air. Generally, the biggest energy saving Hoxton Hall, an 1860s music hall in London which is now ventilated using the ducts from the original sun- burners (Photo: Peter Guenzel) An original advertisement for Sugg’s Ventilating Sunlight which is similar to the system used at Hoxton Hall (Image: William Sugg & Company Ltd) Original fittings refurbished with new LED light sources at the Mayflower Theatre, Southampton (Photo: Tom Lee)