How do bees lower the temperature in the hives?

They cluster together in the hive and "shiver" to generate warmth. They feed on stored honey. Some individuals will die during the winter but the queen and most of the hive will emerge in the spring to gather nectar and pollinate plants. They do seal up small cracks sometimes with "propolis" but, in a natural cavity nest, leave the opening as it is and go deeper within for warmth.