> In theory, you could also circulate cold water in the summer Yes, but it isn't very common at all for one simple reason: condensation. You have to keep the t

> In theory, you could also circulate cold water in the summer Yes, but it isn't very common at all for one simple reason: condensation. You have to keep the temperature of the coolant above the dew point, which requires knowledge of ambient temperature and humidity. That means your coolant isn't actually that cold, so it can absorb less heat before needing to be re-chilled. It's overall pretty inefficient.