The Building Conservation Directory 2022

14 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 C AT H E D R A L C O MM U N I C AT I O N S The Harold Pinter Theatre in London’s West End: like most Victorian theatres, the use of complex architectural forms and rich details, inside and out, make much of the building’s external envelope extremely difficult to insulate. (Photo: Tom Cronin) of where energy is being spent and which improvements will give the most benefit. A key point made at the conference by historic theatre specialist David Wilmore was that you must first understand your building. Studying the original building design often reveals an innate logic as to how the space should be heated and ventilated, that is then lost over time through addition and adaptation. For example, rooflights may have been sealed, ducts blocked and wholescale changes made to heating and lighting. A thorough understanding of how a building was originally conceived provides a solid foundation for improvements. Another clear point from the conference is that although the environmental impact of a historic performance venue is multi- faceted, there are clear principles that apply as much to the environmental improvements of historic buildings as to the environmental design of new ones. These include: • Using clean energy sources • Using efficient fittings and controls • Maximising insulation and air tightness to prevent heat loss • Minimising embodied carbon in new materials • Minimising energy used for ventilation and cooling The real life examples that follow illustrate the type of improvements that can improve the environmental performance of a historic venue. LIGHTING Part of the reason Georgian and Victorian theatres burnt down so often was that the lighting was originally provided by an open flame, first by candlelight and then gaslight. It would take little for flammable scenery or curtains to catch light and fire to spread. Gaslight was replaced by electric tungsten lighting early in the 20th century, giving a safer and suitably warm light but still using a lot of energy. Later in the 20th century newly available fluorescent and early LED lighting was very cold in colour and was avoided by theatres that needed to keep an atmospheric setting. Only recently has it been possible to produce LED lights that have a warm colour temperature, are low in cost and, crucially for theatre house lighting, can be dimmed seamlessly down to very low levels. Aside from efficiency, the advantages of LED lighting include producing far less heat, reducing cooling loads and being so small they can produce dramatic lighting effects in an interior by hiding light sources within and behind decorative detail. In this way dramatic or coloured interiors can be created while retaining an authentic colour scheme. Lighting designers Jim Morse and Hoare Lee have lit historic interiors such as the Apollo Victoria and Hammersmith Apollo for dramatic effect, while retaining the historic decorative scheme. INTELLIGENT CONTROLS Another easy improvement for any historic venue is to control energy use during periods of low occupation. In the past Passive ventilation at The Parabola Arts Centre, a new extension to a grade II* listed villa at Cheltenham Ladies’ College: fresh air is brought in from an undercroft and rises by a chimney stack effect as it warms, before being released at the top of the auditorium. (Photo: James Brittain)