As African land snails are originally from a tropical climate, they should be kept at around 20-26 degrees celcius.
If the tank is in a cold room, a heat mat can be used to maintain the temperature of the tank. Many people use heat mats throughout the winter as well. Heat mats should be attached to the side of the tank, rather than sit underneath, and it should cover around half of the side of the tank. Insulation should be placed on the other side of the heat mat, and underneath the tank to stop the heat from escaping. Polystyrene is best for this, but you can also use bubble wrap or towels.
Snails should be kept out of direct sunlight, so don’t try and heat the tank up by placing it on a windowsill.
African land snails also like humidity, so spraying them with water every day is important. Achatina Fulica prefer less humid conditions to other giant African snails, so don’t get them too wet. Humidity is best at around 80%, you can check this with a small hygrometer.