Information about charging the cost of used electricity

In Brazil (where my house for rent is), it's usual to charge the guest the exact costs of the electricity used.

I've read several articles about this here, and I understand that Booking.com doesn't facilitate that.

I understand it would be quite complicatied to do so, although I think that charging guests their own usage has a much higher enviromental impact than the superficial items Booking.com asks of the host (like not using plastic straws or even wheter the electricity is "green" or not.
If a guest is aware that he'll pay what he has used, any guest (even the not very "enviromental aware" ones) will try not to be wastfull.

But I don't mind too much if I have to take care of billing and receiving payment afterwards, however I would really like to inform the guests beforehand about this.
It should be their right to know this and certainly would help avoiding any difficult discussions about this.

So my question is: how can I inform the potential guests in the add ?