Thermostats are locked at a maximum of 21 degrees and all rooms are capable of sustaining that temperature or being cooler. Providing that tenants behave sensibly they will always be warm, but they don't. For example I visited one recently and the heat hit me as I walked in, the heating was on and he had a fan heater by his feet. The tenant was in a tee shirt and looked hot.
He complained that although the heating was on then bedroom wasn't warm enough. So I checked why. He'd got two large wardrobes in front of the radiator. There was no need to ask why, he'd moved them there to make room for a huge flat-screen TV on the wall where the wardrobes used to be.
If tenants want to behave like this they shouldn't expect us to foot the bill.
As for card meters, it is something we have considered but we're talking about 100+ meters and we've not figured out how to deal with top-ups. Unless there is a system you know of that can be topped up by phone or at a local shop etc.
Can't you just increase the temperature on the lockable thermostats?
As well as being expensive to run, constant use of fan heaters will start to burn the socket outlets. You might have a ring main per room but what is the incoming supply to the property, if you start blowing the cutout fuses the electricity company will charge you for coming out to replace them!
This may be judged by some off-topic but if you communicate with your customers, your clients, your tenants as you do here, is there perhaps something else you could do?
I've always found striving for mutual respect & dignity pays dividends.
I am legally unqualified: If you need to rely on advice check it with a suitable authority - eg a solicitor specialising in landlord/tenant law...
Have you considered incentives?
The way we do it with students is a weekly estimated charge added to the rent, and an extra charge if they are over, or a rebate per year or at the end of the tenancy is they are consistently under.
That would need to match your metering (per room or per house) arrangements, and you could still have the extension lead issue.
It goes without saying that insulation and ventilation setups should be optimal.
Refer Mad Regulators to Arkell vs Pressdram.
We pay a local shop to sell the electric cards on our behalf.
Heating bills are the bain of HMO's with inclusive bills. We had a Sudanese chap in two weeks ago complaining that one of the English sharers was switching off the central heating at 2a.m. I was almost lost for words.
Stalkers, please go over this comment with a fine tooth comb.