In message , jimmy
writes

This is my first season with a new greenhouse and I am wondering what to do
with it during the winter. This comes down to the cost of heating it. Does
anyone have any information about (or links to sites with information) about
the running costs of various electric heaters in the UK. (I am not really
interested in paraffin heaters).

How big is your greenhouse? How warm do you intend to keep it?
Are you prepared to bubble wrap insulate it for the winter?

I use a greenhouse 3kW fan heater for my 10x20' with a split in the
middle so that the blind end is kept warm (min 5C) and the other just
frost free. Everything that could be is insulated with bubble wrap.
Thermostatic vents are allowed to open at 10C internal temperature for
fresh air in winter.

A quick and dirty rule of thumb is that heating costs are roughly
doubled for every 5C above ambient the inside temperature is maintained.
It is very important to have a good thermostat and decent movement of
air.

It was cheaper for me with electricity than with paraffin because you
don't need so much ventilation or have huge condensation problems. The
only minor drawback is that installing electricity in a greenhouse
properly is expensive. But you gradually recoup on the running costs.

Regards,
--
Martin Brown