It’s November 2025, and I have been looking deeply into our options as a church to decarbonise our heating for a couple years. I thought I would share some of my learning from this time, learning gathered through talking with other churches, monitoring temperatures and understanding how this old building (Grade II* listed) behaves, exploring the various options and getting some guide estimates of cost. It has been very interesting and sometimes surprising.

On the way, I’ve set up a Facebook group Churches Seeking Net Zero aimed at anyone involved in such churches, or assisting them, for discussion, questions and information.

Background

For those who are not already familiar with our story, All Saints is an old Anglican church built at the end of the Victorian period. It was the third church to be built on the site (the original Belltower is 14th Century), updated to be more able to meet the needs of the community.

It is a very busy church, in use five to seven days a week. There are a few offices with a large number of staff, youth and children’s work, a community meal and on another day a cafe, the usual music group and bell ringing practice, several prayer meetings and four services a week of varied styles. Alpha groups run during each term with the occasional Youth Alpha in addition. Being the ‘civic church’ for the parish, we also have the usual schools services on the usual festivals, as well as Veterans Day and Remembrance Sunday, and Christmas lights switch where we play a key hospitality role for the community. Of course, there are the usual weddings, funerals, and a good many baptisms in our baptistry pool as well as the old stone font.

The Tower end of the building holds a modern inner construction of two floors, with offices, meeting rooms, kitchen, toilets and lift, with a fairly efficient gas central heating system. The other two thirds of the church is the classic Nave and Chancel with Side Chapel and Vestry and Choir Vestry (now Studio) which is heated by a separate gas boiler and almost unique Victorian radiators (these were the focus of experiments with settings this year). Our total gas consumption is historically ~73,000 kWh, and electricity was ~25,000 kWh in 2024 (before we installed solar panels – but that’s another story).

Monitoring temperatures

To understand how the building responds to heating, and to keep tabs on whether or not it is warm enough, I placed several thermometers at different points in the church, including one on the Pulpit (to hopefully be representative of the Nave temperature) and one in the apex of the Nave by the Parish Centre. When it’s near freezing outside, it was about a degree cooler at the apex, and  when it’s sunny and over 10° outside, it was roughly a degree warmer. This demonstrated to me that the apex and the Pulpit are roughly the same temperature in our church, and there’s no discernable stratification.

There are other temperature sensors in the Parish Centre – in each of the offices and the large meeting rooms. This demonstrated to me that the upstairs meeting room (with no external walls) maintains its warmth the best – especially after the loft space above the ceiling was insulated. The Main office used to require electrical heating in addition to the radiator, but now the window has been secondary glazed, it’s reliably cosy.  The upstairs offices are adversely affected by each having half their ceiling be the underside of the roof with space between the rafters open to the loft area. Sheep’s wool to fill the spaces between the rafters has significantly improved occupant comfort. Monitoring the Studio, which needs electric heaters to boost the warmth as an office, has led to having the windows secondary-glazed and the ceiling insulated which has improved the comfort levels (though still chilly, with a solid floor, windows, two external walls and doors).

When it’s consistently near or below freezing outside, day and night, the church struggles to get above the maintained temperature. The usual cold weather average in the Sanctuary is around 15.5 but in the extra cold weather it is a bit lower, around 15.2 average, and the Sunday temperature was only able to reach, and maintain, 16.4° while external temperature was below freezing.

Talking to other churches

As part of developing my understanding of how the different ways of heating a church worked for other churches, I started searching for and visiting, or talking  to, a number of churches around the country. One measure of how happy they were with their heating is what they had before – anyone who had storage heaters was very glad to move away from them, both for economy and comfort!

Infrared (plus pew heaters if it’s really cold) performs very well in relation to storage heaters, and is very flexible and ‘on demand’ for one day or less per week. Several churches have Air-to-Air heat pumps which have massively increased their comfort while reducing their energy bills. It also has the perceived advantage of being ‘on demand’, useful for one or two days a week (though it can be used economically all week long if it’s in a busy church). For on-demand heating, one needs to understand the thermal behaviour of the church at different temperatures. If it’s freezing outside and 8° inside the church, 4am is not early enough to turn it on for a 10:00 service even for a fast-reacting Air-to-Air system. It likely needs to go on the day before.

Few churches have Air-to-Water systems. I found a couple with Under Floor Heating, a particularly efficient way of heating at slow background levels. Another church has UFH linked to a Ground Source heat pump, working well for them for many years maintaining an ambient of 17°. A couple large churches have recently had ASHP installed to feed radiators and early signs are excellent for comfort, looking okay for cost too.

A low carbon heating symposium

In March I organised a Low Carbon Heating Symposium, and invited the various experts I had been talking to along the say to present for their expertise, followed by a panel discussion. I was drowning in all the information I hadhttps://www.coventry.anglican.org/info-for-parishes/caring-for-the-environment/net-zero/zero-interest–podcast.php been collecting, and hoped that this public discussion might clarify the issues for me. I invited various people related to the church Net Zero journey, as well as people from churches also exploring their options. The All Saints Ladies Bible Study group very kindly catered the vent for me with their home cooking.

I’m very grateful to James Hodgson of J&M Renewables; Michael Cosham of DG Climate Control; Kevin Chand of Connect Infrared, and Matt Fulford of Inspired Efficiency, for without their expertise we would have had nothing. Also thanks to Colin Angus, the Net Zero lead for Coventry Diocese, for being MC (listen to his podcast, Zero Interest).

It was all day and very interesting but far too long to record everything. However here is a 60 min recording of the final summing-up session by Matt Fulford, plus the following panel discussion.

Our real-life heating experiment

In autumn 2025, I’ve ventured some experiments with the heating in the Sanctuary in order to understand more about heating an old church.

Among the things I’ve learned are:

  • The different effects of different flow temperatures on warming the space (60° is okay, 45-50° is more efficient while the average temperature is above  5°).
  • How long it takes for the Nave temperature to rise by 1° in relation to the external overnight temperature (2 hrs if 10°, 3 hrs if 6°, 6-8 hrs if <3°)
  • Maintaining 16° ambient is quiet efficient, boosting to 18° is significantly more gas.

Resources

A great resource for our learning has been the Facebook group Heat Pumps UK and Ireland. It has been a helpful source of information and discussions, but we’re always aware that a confident or strongly expressed opinion doesn’t mean they’re right. Another helpful resource has been the Heat Geek channel on YouTube, which explains a lot of the technical decisions in consumer-friendly language, and does experiments exploring different aspects of installation and controlling. There have also been a few accounts of personal heat pump experiences such as from the Electric Vehicle Man channel, or Tom Bray.

References