When we fitted a ceiling fan in our living room, the instructions stated that in summer, it was best to have it blowing upwards (sucking air up from floor level

When we fitted a ceiling fan in our living room, the instructions stated that in summer, it was best to have it blowing upwards (sucking air up from floor level) because that air would be cooler, and in winter from the same principle, you could blow warmer air down onto the room occupants. In practise it didn't work that well - the temperature difference in a couple of metres of air space (in a single average-height room) is pretty minimal. We left the fan blowing downwards to use the windchill effect in summer - that worked well enough.