Heating, lighting and zero carbon


In February 2020, General Synod resolved to make the Church of England carbon net-neutral by 2030. Reducing our carbon footprint is something that requires action in every part of our lives. Where church buildings are concerned, an obvious place to start is the heating and lighting – the two systems that consume the most energy. Many parishes are looking at renewing them, since in numerous cases both are life-expired and inadequate. This provides an excellent opportunity to make your church fit for a zero-carbon future. Green energy is a huge topic. You can download a formal statement of the policy of the Diocesan Advisory Committee (DAC) on the subject here. You can find a source of extensive news, guidance and reference information produced by the Church Buildings Council here. The Council also has a portal with a wide range of information just about heating in churches here. What follows is a starting point and doesn’t pretend to be comprehensive. Moreover, every church is unique, every project is unique, and only you as a parish can ultimately decide the best way to proceed. But it will help you to make sense of a sometimes confusing issue and the DAC’s thinking on these matters. All the advice given here is based on casework involving heating and lighting that it has handled in recent years.

Lighting

This is the easiest win where reducing carbon emissions is concerned. Modern lighting units based on LEDs (light-emitting diodes) are a great deal more energy-efficient than lighting units previously installed in churches. They also have the advantage of a much longer service life. We encourage all parishes to switch to them by 2025. It’s possible to convert some existing lighting units to run on LEDs fairly easily, and that is usually a List A matter. But when carrying out any work to a lighting system in a church, it’s always worth taking a slightly wider view. When was the wiring last tested and is it safe? Will it need to be overhauled before you can upgrade any of the equipment?

At St Margaret’s in Bethersden, LED feature lighting has been used to bring out the splendid 19th century reredos with its painted texts.

Depending on what you find, it could be worth looking at a comprehensive redesign. As with any new service equipment, it’s good to get advice from a consultant in the field who doesn’t have a vested interest in selling you a particular product and can take a wider view. Look at improving the control equipment, so that you can zone the system and only switch on lighting in areas of the building where it’s needed. Bear in mind that some LEDs can’t be dimmed over a wide range – at any rate, not without causing them to flicker. Also, beware of over-lighting – LEDs usually emit strong white light, but the interiors of historic churches were never intended to be brightly illuminated throughout, and excess lighting units simply waste energy. It might be worth installing feature lighting to reveal, say, an historic painted ceiling, but is it really worth it with a plain timber roof structure?

Heating

An historic church can be a cold place. Though it may not be possible to make it as warm as a modern house, the DAC wants you to have a church building that is comfortable to be in – not just for worshippers, but for anyone else using it outside service times. When churches first began to be equipped with proper heating during the Victorian period, ‘wet’ systems were installed. These consisted of a coal-fired boiler, usually situated in an underground chamber or lean-to extension, which supplied cast iron heating elements with hot water. These might take the form of large radiators placed against the wall or by the pews. Alternative, they might be in trenches, so that the heat rose upwards through cast-iron heating grills.

At SS Peter and Paul in Appledore, the old boiler house, which is now redundant, has been reconstructed as a toilet.

Oil and gas heating

If your church was reordered in the 19th century, it’s likely that you will have at least the remains of a heating system such as this, or at any rate something based on the same principle of heating water and feeding it through pipes and radiators. But the boiler will now be fired by heating oil or gas. These are both fossil fuels and produce carbon dioxide when they burn. They need to be replaced by a clean, carbon-free source. Oil-fired boilers have the biggest carbon footprint and are a priority for replacement. The DAC will not recommend the replacement of one oil-fired boiler with another.

But if not an oil-fired boiler, then what? In theory, it ought to be possible to heat the water by electricity instead, since this can be generated using renewable sources. But although electric boilers are available, they’re not cheap to run, as you may know if you have a domestic immersion heater. Although technology in the field is changing all the time, it could be some years before cost-effective electric boilers become commercially available. It’s more efficient to use the electricity to feed heating units directly. For that reason, if you have a failing oil-fired heating system, you need to look at replacing it outright.

If you have a failing gas-fired system, in exceptional cases the DAC will look kindly at a request to put in a new gas-fired boiler. We appreciate that replacing a heating system in its entirety is an expensive and time-consuming business. But this is done on the strict understanding that this is just a stopgap solution to buy a parish time. A modern gas-fired boiler has a service life of about 10 years. When yours reaches the end of that, you won’t be able to install another one – your Archdeacon won’t allow it, and in any case the government has signalled its intent to phase out gas boilers in the 2030s. You will therefore need to start planning for the longer term. In the future, it may be possible to convert gas-fired systems to run on instead on hydrogen, which doesn’t produce carbon dioxide when it burns. But this technology is still in its infancy and it may be some time before it’s commercially available and feasible for use in churches.

Ground- and air-source heat pumps

These are a form of renewable heat generation that extracts latent heat from the ground or ambient heat from the air and passes it through a heat exchanger, where it is transferred to the water in a heating circuit, which is connected to radiators. Essentially, they function like a refrigerator in reverse, moving heat from a warmer place to a relatively colder place to ensure that the latter remains at a constantly high temperature (as opposed to extracting heat from one place to ensure that another remains at a constantly cool temperature).

A cross section of the ground-source heat pump installation at St Mary’s in Ashford, installed when the nave of the church was reordered with under-floor heating to allow it to be used as an arts venue.

Ground-source heat pumps (GSHPs) have been successfully used in the Diocese of Canterbury at St Mary’s in Ashford and St Stephen’s in Lympne. But using a GSHP isn’t just a simple matter of disconnecting your existing wet system from one source and connecting it up to another - it will involve looking at much wider issues about how you use your building. Though it can pay dividends in the long run, the installation costs are high and it’s not a quick fix. Here are some points to bear in mind when deciding whether a GSHP is right for your church.

  • A GSHP needs a large amount of underground tubing, through which liquid is pumped to extract heat from the ground. This may take the form of a large coil which is buried beneath the surface, or else a deep borehole. A trench is also necessary to connect the coil or borehole to the church building. Both these options involve a large amount of excavation, and so have serious implications for below-ground archaeology and burials. That doesn’t mean that you can’t work around these things, but you’ll need an archaeological survey, which will inflate the cost, as will dealing with any remains that need to be recorded or reburied.
  • GSHPs can’t be used in every location. They work best in areas with a high water table. They aren’t suitable in areas with a substrate of chalk or rock. You’ll need expert advice to find out whether the ground conditions beneath your church building make a GSHP viable before investing any time and money in developing a proposal.
  • Though the source of the heat may be free, that doesn’t mean that a GSHP is free to run. An electric pump is required to keep water circulating through the system and has to be in operation permanently when the heating is on. As a result, running costs can be high. You will also need a three-phase electrical connection to operate it. Some churches still have a single-phase supply, so you’ll need to establish with UK Power Networks at an early stage whether it can be upgraded and to budget in the cost of doing that.
  • A GSHP won’t deliver water at as high a temperature as an oil- or gas-fired boiler. It therefore isn’t an adequate substitute on its own – it is best suited to maintaining a comfortable background temperature. You will need extra heating to boost it during cold snaps, when its output may be insufficient.
  • For the same reason, a GSHP takes a long time to heat up a building and is usually kept running for a lengthy period. This is fine in the case of a church that is in regular use every day for regular services and events outside service times. But it doesn’t make economic or practical sense for a church that is used infrequently.
  • GSHPs tend to be connected to under-floor heating, which is the most efficient way of using their output, rather than to conventional radiators. It’s unlikely that this will already be present in your church building – it is fairly recent technology – and installing it involves substantial expense and major intervention to the fabric of your church. You’ll need to introduce a new floor surface and you may need to replace the seating, too. None of these things should stop you from pursuing it, but it makes the most sense if your vision is for your church to be a flexible space that can be used by the wider community outside service times.

The installation of an underfloor heating system powered by a ground-source heat pump at St Stephen’s in Lympne was combined with a reordering scheme. A new floor surface was introduced and the Victorian pews were made into portable items of furniture.

Instead of a coiled pipe below the ground or a borehole, Air Source Heat Pumps (ASHPs) take the form of heat pumps outside the building. These need to be placed in a location where they have plenty of air to circulate around them. They are utilitarian in appearance and you may wish to consider introducing something to screen them from view, such as a hedge. They can also be noisy in operation. For all these reasons, you will probably need planning permission for them. As regards their performance, everything said about GSHPs applies here as well. An ASHP doesn’t work like a gas- or oil-fired boiler, so you’ll need to think about how you use your building and your plans for the future to decide whether it’s right for you.

As regards the external equipment, while your local planning authority should be aware of the need to replace fossil-fuel heating systems and its implications such as this, the DAC has no locus here. You’ll need to check at an early stage whether a planning application for the equipment is likely to be granted. You should also bear in mind that an ASHP doesn’t function well in really cold weather (i.e. around freezing), when the amount of electricity required to keep it in operation is disproportionately large relative to the amount of heat generated. As of August 2021, no ASHPs are in operation anywhere in the Diocese, but one scheme involving them is at an advanced stage of development and we very much hope that there will be more.

Electric heating

As the National Grid became more extensive in the 20th century, electric heating started to become common in the numerous rural churches that still lacked any form of it. The heaters that survive from that time have often made a bad name for themselves. They’re unsightly (and even more so when they glow pink in operation), gobble electricity and, if they work at all, focus all their heat at a single point. If you’re sitting nearby, your upper half roasts while your lower half freezes.

For these reasons, churches can sometimes be wary about going electric. But the technology has much changed in recent years and is improving all the time. In many cases, electric heating is the best option for a church looking to reduce its carbon footprint. Electrical energy can be generated cleanly using renewable sources or procured on a green tariff. Modern electric heaters are smaller, much more efficient and much more effective. They allow heat to be directed to where it’s needed most. There is no need to switch them on hours before the building is going to be used, as is the case with wet systems - no energy is wasted heating empty space before worshippers begin to feel the effect.

Coronas with electric heaters attached to them have been successfully used at St Catherine’s, Preston-next-Faversham. They can be installed with very little intervention to the fabric of the building and the wiring tucked away unobtrusively, as shown here.

Electric heating can take all sorts of different forms. There are small heaters which are fixed unobtrusively to the underside of pews. There are ceramic panel heaters attached to walls and columns. There are coronas suspended from the roof structure with radiant heaters attached to them and, sometimes, lighting units as well. There is no one correct solution for everyone – what you choose depends on the nature of your building and how you use it. It’s well worth seeking independent advice from a heating consultant. As with lighting, you need someone who understands what you require and doesn’t have a vested interest in selling you a particular product. Discuss the matter with your Inspecting Architect. Contact the Care of Churches Office for more advice and to inspect electric heating systems in operation elsewhere in the Diocese.

Don’t forget that you will almost certainly need a three-phase electrical supply in order to run electrical heating. Some churches still have a single-phase supply, so you’ll need to establish with UK Power Networks at an early stage whether it can be upgraded and to budget in the cost of doing that.

Solar panels

The resolution by General Synod has prompted a lot of churches to look at zero-carbon forms of power generation. The most popular is photovoltaic (PV) arrays, which convert solar energy into electricity. These are sometimes known as solar panels, but need to be distinguished from other forms of solar-powered technology, such as the panels used to heat water. The question usually asked first about PV arrays is, ‘Will the DAC allow us to install them?’ As a general rule, the answer is usually ‘yes’, provided that the array can be installed in a place where it won’t be visible from the ground and thus won’t affect the appearance of the building.

A PV array has been installed on the roof of the south aisle of St Anthony’s in Alkham. But you’d never know it to look at the church from the ground.

The most suitable locations are flat roofs or roofs with a low pitch hidden behind a parapet. It’s sometimes possible to install PV arrays in roof valleys, although only on parts of the slope that aren’t in shadow. You may need advice from a structural engineer on whether the roof is capable of bearing the extra weight, and any urgent major repairs to it will need to be carried out before the panels are installed. Also, be aware that in some situations planning permission may be required in addition to a faculty because of the change in appearance of the building, so double-check with your council. There is associated electrical equipment, such as an inverter (which converts the direct current produced by the panels to the alternating current used in the National Grid), but in all but the smallest buildings it shouldn’t be difficult to find a home for it.

The main obstacle to PV arrays is not heritage concerns, but the economics of their installation. In the past, they had a considerable advantage. They fed energy into the National Grid, in effect turning churches into miniature power stations. Under a government scheme called the feed-in tariff, parishes could sell the electricity they generated to their energy supplier. In time, the PV array would pay back the cost of installation and, after that point, the electricity exported from it could be offset against the energy provider’s bills. In the Diocese of Canterbury, PV arrays have been installed at St Anthony’s in Alkham, St Mary and St Ethelburga in Lyminge and St Mary’s in Kennington.

Unfortunately, the national feed-in tariff was subsequently abolished. While it still operates for pre-existing installations, no new applications have been accepted since March 2019. That is no reason not to look at installing PV arrays, but, apart from some isolated exceptions to the rule (check with individual local energy suppliers whether they operate a feed-in tariff), there may well be no financial advantage in doing so. The payback time will be much longer than it was in the past. If the electricity can’t be exported, it has to be used where it’s generated, but since the weather is unpredictable, periods of supply and demand don’t always coincide with each other. That means that you need to be able to store what you generate until it’s needed. Battery technology is improving all the time and should make it possible to balance supply and demand better. However, as of summer 2021, there are no such systems in operation anywhere in the Diocese of Canterbury.

Insulation

Reducing your carbon footprint isn’t just about obtaining energy from clean sources, it’s about reducing the amount you consume in the first place. One way of doing this is to make your church building more energy-efficient by reducing the amount of heat escaping from the walls, windows and ceiling. If your church dates from the 20th century and isn’t listed, there will probably be no concerns over the visual or physical impact. You can easily introduce measures such as ceiling insulation and secondary glazing, and enjoy the benefits they bring, including lower running costs.

But it’s important to be realistic about what’s achievable here compared to, say, your own home. In an historically significant church, such proposals are not always possible to enact without visual or physical intrusion and, if that’s the case, they won’t be supported by the DAC. Moreover, introducing impermeable layers that don’t allow heat and moisture to pass through them can have serious consequences for historic fabric, which performs very differently to a modern building. This can potentially cause damage that will be expensive to put right in the long run. In any case, medieval churches were built to very different standards and lack even basic features such as cavity walls to stop heat escaping. It’s not possible to keep them warm in the same way as the environments where most of us live and work.

But there are still plenty of changes that you can make which will have a positive effect. You’ll find a lot of these among the recommendations in your last quinquennial inspection report. These are the measures aimed at keeping the envelope of the building in good order and ensuring that as little as possible precious heat escapes – mending broken quarries in leaded lights, plugging eaves gaps, introducing insulation beneath pew platforms, installing draught lobbies and so on. On a bigger scale, you could also consider installing screens and partitioning off an area such as a side chapel that can be heated independently of the rest of the building for use in colder weather. More guidance on the subject is available from Historic England here.

Financial assistance

We recognise that replacing an entire heating system can be expensive. But there is financial assistance available, and you will find below links to organisations or sources of information that may be able to help you to obtain it.

Some local authorities provide grant aid for organisations looking to reduce their carbon footprint. Here are the websites for all the local authorities covered by the Diocese, where you can find out more: