Been to look at an old Basalt stone walled church that is being renovated. They have repointed all the outside with lime mortar and fixed the roof and all the lead work. Next on the agenda is the inside.

The building is grade listed so cannot remove the high ceilings ect. It's a very large volume with high vaulted ceilings. I need to come up with a heating scheme and any energy conservation/ insulating ideas.

The walls are being lime rendered on the inside. It's possible that we could partially clad the walls to provide services voids and add insulation. We could do wood fibre or cellulose.

If anyone can suggest any ideas it would be welcome. I'm thinking of radiant heating. A bit more research is needed.

What will the use of the church be once renovated. If it will still be a church then consider its usage - an hour or so at a time with long periods empty. IMO a waste trying to heat (or insulate) the building structure.

What they do here (with winters down to -18 or so) is to put electric resistance heaters (made in a tube formation) fixed to the underside of the pews. These are switched on half an hour before the service and switched off at the end, or sometimes just before the end of the service. This type of heating gives warm seats and radiant heat for legs and is generally adequate as the congregation are usually wearing their overcoats.

Use candles

I'm with Peter, tube heaters under the pews if they are being kept. In addition maybe some IR heaters above head height pointing down is also common. Wouldn't bother with insulation either given the likely usage. It generally isn't a good idea to get church buildings too warm, you get it warm and a load of folk come in for a funeral etc and fill it up completely - it gets very, very hot and stuffy and people pass out from bad air/stress of the occasion/etc. Folk will normally have their jackets, they can always cope with too cold, too hot is a real problem.