A SPRING IN THEIR STEP An ambitious project is under way to replace Bath Abbeys 150-year-old heating system with low-energy underfloor heating, using heat recovered from hot springs rising in the nearby Roman Baths. BuroHappold Engineerings Neil Francis describes the challenges encountered at the Unesco World Heritage city site P eople have used Baths thermal springs for at least 2,000 years, with the citys Roman Baths topped up with 1.2 million litres of hot water flowing daily from hot spings. Since the 1980s, however, bathing has not been permitted and the majority of the hot water has, literally, gone down the drain. This is set to change over the next 12months, when the neighbouring 16th-century Bath Abbey starts employing hot spring water to provide heat for its 420,000 annual visitors and 600-strong congregation. The Roman Great Drain, carrying 45C spring water from the baths to the River Avon, passes close to Bath Abbey. The plan is to capture energy from the hot water in the drain, using heat exchangers, before boosting the temperature with heat pumps located in an expanded plantroom in a basement vault within the Abbey. An urgent need to replace the ancient buildings precarious flooring created the opportunity to install underfloor heating. More than 8,500 burials have significantly weakened the floor structure, so in 2010 the Abbey launched its Footprint Project to repair it, install a low energy heating system and create new meeting, catering and toilet facilities. There will also be a Discovery Centre, telling the story of the Abbey. Existing heating was also at the end of its useful life. Cast-iron pipework and gratings are more than 150 years old, and there were comfort issues caused by excessive cold downdraught fromthehuge areas of glazing in the Abbey (see diagram, top right). Early design-stage studies quickly identified underfloor heating as the preferred background heating solution, PROJECT TEAM Client: Bath Abbey Architect: Feilden Clegg Bradley Building services engineer and sustainability services: BuroHappold Engineering Heat pump specialist: Isoenergy 46 February 2019 www.cibsejournal.com CIBSE Feb19 pp46-48 Bath Abbey.indd 46 25/01/2019 18:31