If one does not believe in electricity, there is another approach. The pyramids were built in such a way that they could help the kings ascend to Sun Ra, the god of the sun. The kings themselves were also seen as gods who lived on earth.
After their death, their path back to the realm of gods was paved. For this reason, the tombs were equipped with items that the king could need in his afterlife, such as live animals, gold, and warmth.