system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do large-footprint buildings like supermarkets have such high ceilings?
gpt
1) To make it feel more open. Large buildings like that actually feel very claustrophobic if they have low ceilings. 

2) Heat management. There are a lot of people in that building and that produces a lot of body heat. Having high ceilings gives a place for that heat to go and makes cooling the building cheaper. Intakes will be up high and AC outputs will be lower down taking advantage of natural air currents.