@Simon2668 I'd say to calculate how much the cost of gas you used to pay in the past compared to now, and up your nightly price by enough to cover it. It will likely only amount to a very small increase per night, not enough to affect your bookings.
All businesses increase their prices as the cost of living goes up.
It depends on the demographic of guests you tend to get as to whether to just eliminate washing machine use. I only host one guest in a private room and my washing machine isn't offered to guests. They sometimes wash out an item they need clean in a pail, and if I'm doing a wash myself, I'll ask if they have any items they'd like to add to it.
But if your clientele is families who stay for at least several days, a washing machine could be the difference between a guest choosing another similar listing over yours.
There is also nothing wrong with asking guests to please be respectful of energy use and only do a wash when they have a full load. There are people who will fire up the machine to wash one tee shirt and a pair of socks they want to wear that night. These are usually people who don't pay for their utiilities at home- they probably rent where utilities are included, or they're young and still live with mom and dad who pay the bills 🙂