BCD SPECIAL REPORT ON HISTORIC CHURCHES 31st ANNUAL EDITION 43 trigger for installing underfloor heating, which is backed up with electric panel heaters for the colder months. Secondary glazing, LED lighting, and insulation have all added up to improved comfort and extended use of the church, while being environmentally and financially more sustainable – not to mention the conservation benefits of eliminating the condensation that was damaging the fabric of the building. So reduced carbon and increased comfort is perfectly possible with air source heat pumps. They won’t be suitable or possible everywhere, however. In less regularly occupied churches, heating people with infrared or pew heaters – even heated cushions – could still be better than heating the whole space if it’s only used once or twice a week. THE LIGHT OF CREATION – SOLAR PV Heat pumps are even more sustainable when paired with home-generated energy, and a solar PV (photovoltaic) array can be an obvious addition. PV panels capture the sun’s energy using cells which contain layers of semi-conducting material, usually silicon. When light shines on the cells it creates an electric field across the layers, allowing electricity to flow. A typical panel can generate around 335W of energy in strong sunlight but as long as the roof is not consistently in shade or likely to be covered by debris, a solar array can generate energy even on a seemingly dull day. Rainfall is usually enough to keep them clean on a pitched roof and the panels are built to last – typically still 80% efficient after 25 years. With only the DC to AC inverter likely to need replacing every ten years or so, they are pleasingly low maintenance. The east–west orientation of most churches means they have large southfacing roof areas which are ideal for a PV array. However, where a church is listed, its roof is very much part of the historic fabric, and solar panels can be visually intrusive. Fortunately, many church roofs have high parapets which help to screen the roof, while others have hidden valleys, making solar PV an easy option. Gloucester Cathedral has 150 panels fitted to its south transept roof, while Holy Trinity Church in Cheltenham took the opportunity to install a 10.8kWp solar PV array and extra insulation during re-roofing in 2020 – part-funded through an EU scheme Severn Wye was delivering at the time. With the work promoted widely across the diocese and beyond, the improvements have brought reputational benefits as well as financial and environmental ones. Even if the roof is visible the case for solar panels is strong; the zero-carbon agenda requires urgent action and rooftop solar PV is a reversible choice. Solar canopies over car parks are another option, with the additional benefit of shading cars on a hot day. Including battery storage will help churches – and households and businesses – get the most out of their energy generation. CUTTING YOUR CLOTH They might have heating challenges in common, but churches are not built or used in the same way. Although Severn Wye’s focus in this project is surveying the buildings, their recommendations are based around the people who use them as much as the physical fabric, taking into account how each building is used and how it might be used in future, to provide a bespoke plan of action for each church. A perfect energy efficiency solution for one might not be best for another. So each church is receiving a bespoke plan for achieving the improvements that will make the biggest difference to them. In keeping with the Church’s belief that small changes can make a big difference, these include no-cost changes to practices and behaviours as well as suggestions for longer-term investments and their predicted benefits. To be achievable, those recommendations have to balance the need for warm, welcoming spaces with the practicalities of affordability, heritage conservation, and the carbon costs in both the short term and the long term. Every religious building is different, and each must be carefully understood to find the right path towards net zero. The solutions might not always be obvious, but we just need the right data and a bit of imagination to find them. For further information on the Church of England’s Net Zero Carbon 2030 goals see www.churchofengland.org/resources/ net-zero-carbon-routemap as well as case studies of previous decarbonisation projects at http://bc-url.com/hc24-w1. ADELE WALKER is Communications Manager for Severn Wye Energy Agency (www.severnwye.org.uk). She has extensive experience in conservation having worked in the past for both Historic England, National Trust, and Cathedral Communications. Technical advice for this article was given by Greg CollierJones, Severn Wye Lead Retrofit Coordinator. St Anne’s, a Grade II*-listed Georgian church in Ings, Cumbria, was one of the first to install an air source heat pump with underfloor heating. as shown by warden, John Hiley. (Photos: Church of England) A solar panel installation on the roof of Holy Trinity, Cheltenham (Photo: Church of England)
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