Underfloor heating (UFH) company Ultra-Fin UK has demonstrated how a Grade I-listed building can undergo an energy efficiency transformation without leaving traces on the historic internal fabric, while future-proofing a switch to renewable heating.
St. Paul’s Church in Covent Garden is not only known for its architecture, 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 has a strong presence in the heritage sector and was exhibiting at the Listed Property Owner’s Club show at Olympia when the team met Westminster Churches Net Zero Forum Officer Alison Moulden, Parish priest Revd. Simon Grigg, and Parish Administrator Phil Hunt, who took a keen interest in the potential of the UFH system designed for joisted floors.
Director Tom Dixon-Smith explains: “The nature of this project inspired us to take on the role of manufacturer, supplier and installer using our own engineers. We produced what became a 250-page document detailing the system and installation method.”
All buildings lose heat through the ground floor, and St. Paul’s Church is no exception. Tom added: “We specify insulation beneath our pipework to avoid downward heat losses. In this case, 50mm of fully non-combustible Rockwool insulation maximises the heat from our system while making the building more energy efficient.”
Insulation support is provided by a tough, A1 fire rated breathable PhotonWrap barrier, which 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 to prevent a shiny glare from between the floorboards. The UFH extends across the whole nave from in front of the Altar to the main entrance, leaving the chancel/ choir’s flagstone flooring in place.
The joisted floors cover 2,900m2 in 10 bays 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. Hard-wired sensors ensure the flooring will not rise above 27°C to safeguard the timber.
Phil added: “The Church nave was heated previously by five radiators which took a long time to heat up (even though we were running the boiler at 80°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 45°C. The Ultra-Fin system caused far less harm to the fabric of the building than the alternatives being considered.” www.ultra-fin.co.uk