This is counterintuitive, but correct. During a phase change, energy is released and absorbed by the substance. For example, when water freezes it gives off energy to the surroundings. This is why orchards spray water on their fruit during a cold snap… the heat given off by the freezing water might be enough to save the fruit from freezing too. Similarly, when the water in the ground around your basement thaws, it pulls that energy from somewhere… and that could very well be the walls, floor, and air of your living space.