Dear Tim
I have been specialising in church heating for the past 25 years and was therefore delighted to read John Love’s excellent article on church heating. This is very good as far as it goes but there are two aspects which need to be added.
a. John Love is right that in many cases the installation of a wet heating system, possibly underfloor heating, is simply not possible on financial grounds or on grounds of disturbance of historic fabric or lack of a suitable fuel supply. In these cases the use of electricity as the heat source is often the only option. If that fuel is used for conventional heating, be it convector heaters, radiant panels or storage heaters, it is expensive to run whilst most UK electricity is generated from fossil fuels where there is major loss of energy in the power station conversion process.
A further problem is that the size of very many parish churches is such that the heat requirements are greater than a traditional three phase 100 amp/phase electricity supply (and quite impossible with a single phase supply).
One way in which it is sometimes possible to proceed is to use a heat pump which can be either an air source heat pump generating warm air or hot water, or a ground source heat pump generating hot water. Large area shallow ground source heat pumps are rarely feasible in churchyards but deep bore versions may be feasible, though expensive. Using a heat pump enables the incoming electricity supply effectively to be enhanced by up to three times.
b. The other vital aspect in any old (especially Victorian or earlier) church is that intermittent heating can be very damaging to the fabric of the building due to rapid changes in relative humidity brought about by rapid changes of temperature. Whereas local (radiant) heating may be desirable in some cases this rarely gives appropriate comfort and the intensity of local heating can cause long term problems with moisture migration into and out of walls, plaster, woodwork etc.
The heating of churches is almost always quite different from heating any other class of building for a whole variety of reasons. Most villages have an Anglican Church and most of these are listed buildings. Most of them have usage patterns which differ from other types of building.
It is not possible to give simple and universal solutions to issues of church heating and expert advice needs to be sought from architects and others when looking at options in particular cases. Some information is published by various national church authorities and by individual Diocesan bodies.
Yours sincerely,
Dr Colin R Bemrose