A recently completed contract for an underfloor heating company has demonstrated how a Grade I listed landmark building can undergo a transformation, in terms of its energy efficiency, without any traces being left on the existing historic internal fabric: while also future-proofing it for a switch to a fully renewable heating source in the coming years.
St. Paul’s Church in Covent Garden is not only known for its architecture - prominent from the famous Piazza - but also as the ‘Actors’ Church’, hosting memorials to film and stage stars from Charlie Chaplin to Sir Noel Coward.
Working with the Diocese of London and under the Church of England Net Zero Carbon programme the Church has achieved what might have seemed impossible less than a year ago.
Established in 2024, Ultra-Fin UK Ltd. already has a strong presence in the heritage sector and was exhibiting at this year’s Listed Property Owner’s Club show at Olympia.
The team met Westminster Churches Net Zero Forum Officer, Alison Moulden, who made the introduction to the Parish priest, Revd. Simon Grigg, and Parish Administrator, Phil Hunt, who took a keen interest in the potential of the underfloor heating system which is designed for joisted floors.
Director Tom Dixon-Smith explains the contractual relationship on the project, saying: “Our business model normally involves supply and training but the nature of this project inspired us to take on the role of manufacturer, supplier and installer, using our own team of engineers.The Church is so important we weren’t prepared to let anyone else complete the project”.
Tom went on to say: “Phil Hunt did a fantastic job of steering the project application through all the Grade I listing and other compliance issues and we supported that by producing what became a 250-page document detailing not just the system but also the installation method.For example, we had to calculate how many notches we would have to take out of the existing joists once the historic floorboards were lifted and also specify the insulation solution over which the system would run.”
All buildings lose heat through the ground floor and St. Paul’s Church is no exception. Tom explained “we specify insulation beneath our pipework to avoid downward heat losses. In this case the 50mm of fully non-combustible Rockwool insulation maximises the heat from our system whilst making the Church building more energy efficient through restricting building heat loss.”
The support for the insulation is provided by a super tough, A1 fire rated breathable PhotonWrap barrier, which also enhances the heat delivery from the Ultra-Fin diffusers by being heat reflective. The membrane was lapped over the joists, held in place with staples and painted black along the top of where it sits on the joists to prevent a shiny glare from between the floorboards.
The composite PEX Aluminium pipe and the Ultrafins were installed during a thirteen-day period in mid-August 2025, before the Company’s engineers completed the connections to the existing boiler and undertook the commissioning. The new underfloor heating extends across the whole of the nave from in front of the Altar to the main entrance, leaving the chancel/choir’s flagstone flooring in place.
The joisted floors cover 2,900 sq.m in 10 bays and they are split into a dozen separate heating zones, prioritising the coldest space towards the Altar, while the pair of eight-port Ultra-Fin Cross manifolds retain spare connections to facilitate the replacement of the boiler with air source heat pumps in the future. There are hard-wired sensors to ensure the flooring will not rise above 270 C degrees to safeguard the timber.
Having overseen much of the work, the Parish Administrator for St. Paul’s, Phil Hunt observed: “The nave of the Church was previously heated by five radiators which took a long time to heat up (even though we were running the boiler at 80o C). We will be carrying out monitoring, but anecdotally, the times we have turned on the heating it has warmed up far quicker, even though the boiler is running at just 45o C.
"The Ultra-Fin system was also ideal for the project because it proved to cause far less harm to the fabric of the building than the alternatives being considered – not requiring the floor height to be built up or screeded, while it remains demountable and – valuably – it was also significantly cheaper than the other systems which would have required far more work.”
