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Elizabeth Tower

Client: Parliamentary Estates

Budget: £120m

Completed: 2022

Elizabeth Tower, which is visited by around 12,000 people each year, is carefully conserved by Parliament’s heritage team. However, as extensive conservation works were last carried out more than 30 years ago, significant work and an investment of £79.7m is now required to safeguard the tower for future generations. As a Grade I listed building and part of a UNESCO World Heritage site, the 160-year-old tower is subject to listed building consent. The design and programme of works have been carefully planned in consultation with Historic England.

As part of our membership of the former Parliamentary Estates Directorate framework, we were initially appointed in 2015 to provide MEP feasibility studies and option appraisals for various options to repair and restore Elizabeth Tower, resulting in the client approving the option to undertake the full repair and restoration works.

Following a competitive tendering process, Sir Robert McAlpine Special Projects were appointed to carry out a programme of essential works to conserve Elizabeth Tower, the Great Clock and the Great Bell, also known as Big Ben. One of the primary objectives of the works is fabric restoration and future protection for the structure, together with the careful removal of the existing MEP services and complete upgrade of the Mechanical, Electrical and Public Health services.

During the detailed design stage, our team undertook various trials to determine the appropriate design principles for various elements of the services being replaced or installed within Elizabeth Tower. Data loggers were placed throughout the tower, which monitored the temperature and humidity over a 12-month period. Once complete, the results allowed our team to determine the optimum fabric protection heating system designed to prevent the build-up of internal and interstitial condensation within the tower, protecting the fabric for generations to come.

Extensive lighting trials were also conducted by our electrical engineers designing the new clock face lighting. This involved testing the proposed light fittings both at the factory and on-site. Factory testing involved witnessing the proposed lamp performance with samples of the proposed replacement clock face glass, whilst on-site trials involved replacing 12 of the existing lamps within the south clock face to witness on site performance. The trial demonstrated that when the proposed LED lamps were at 50% output, this successfully illuminated the clock face and closely matched the output and colour of the current lighting, thus preserving the aesthetic of the heritage site and clock face. Utilising LED technology at 50% output (33W per point) represents a 60% energy saving together with providing reduced maintenance costs and better control using an integrated lighting control system.

MEP works also involved major infrastructure switchgear replacement, installation of a new evacuation lift, replacement of all small power, data, fire alarms, heating and ventilation and the installation of new data and security systems.

All photographs are provided by ©UK Parliament & Jessica Taylor