The good news first: room temperature is home turf
A crested gecko comes from cool, humid island forests and keeps comfortably at the temperatures a lived-in home holds without any heating equipment at all. During a power cut, that means the gecko's enclosure usually needs no intervention beyond being left somewhere sensible while the house rides out the outage. The sensible place is an interior room, away from window glass that radiates cold at night and away from any door that opens repeatedly to the outside. If the room stays comfortable for a person in a jumper, it is broadly comfortable for this gecko.
When cold does become the problem
A crested gecko's comfort has a floor as well as a ceiling: if the house falls cold enough that you are wearing full winter layers indoors and seeing your breath, the gecko needs the same help as the household. Insulate the outside of the enclosure with towels, move it into the room everyone is sleeping in, and only then consider gentle warmth, such as a wrapped warm water bottle set beside, not inside, the enclosure. Check with a thermometer rather than by feel, and aim merely to hold a mild room temperature, not to create a warm end; this species does not use a gradient the way a snake does.
The overheating mistakes an outage invites
More crested geckos are endangered in power cuts by rescue attempts than by cold. A hand warmer taped to this gecko's small enclosure can push it into distress within the hour, a candle or space heater nearby creates the same risk with fire added, and a well-meaning move to sit by a wood stove overshoots fastest of all. Write the rule down for the household: no direct heat on the crested gecko's box without a thermometer reading to justify it. If the gecko is gaping, lying flat and pale, or frantically active, suspect heat before cold and move the enclosure somewhere cooler and shaded.
Misting and feeding on the normal rhythm
Keep a crested gecko's routine boringly normal through an outage: mist one side of the enclosure with dechlorinated water in the morning and evening so it can drink droplets, and refresh its powdered diet on the usual schedule, mixed fresh with bottled water if the taps are off or suspect. A battery torch is fine for checks, but do not shine it into the enclosure for long evening sessions; this nocturnal gecko's day-night pattern is already disrupted by a house using candles and torches, and rest matters to it. Leave the lid closed between mistings to hold the humidity you just added.
After the lights come back on
Once power returns, a crested gecko that is climbing, licking its eyes clean and eating its diet needs no special recovery programme; just confirm the enclosure is back in its normal spot and its normal misting rhythm resumes. A gecko that stays hunched on the floor, refuses food for several nights after temperatures normalise, or shows a suddenly kinked tail or trembling should be discussed with a vet, with your notes on how cold or warm the house became. Sharing the gecko's misting times and diet changes as KinsLe Care Teams duties during an outage means each small job is visibly done, even when the household is stretched thin.