Using the outside air to cool a space is called "free cooling" because?

Free cooling is termed as such because it leverages the naturally cooler outside air to reduce or eliminate the reliance on traditional mechanical cooling systems, such as air conditioning units. This process can significantly lower the energy costs associated with cooling a space since it often utilizes the existing ambient temperature rather than needing energy-intensive equipment to cool the indoor environment.

When outside temperatures are low enough, particularly in the evening or during cooler seasons, the air can provide adequate cooling without the financial burden of energy consumption that normally comes with running HVAC systems. Consequently, this method is particularly appealing for its cost-effectiveness in reducing electricity bills associated with air conditioning.

Using outside air for cooling does not imply that it is always free of operational costs, but the idea is that it minimizes the financial expenditure associated with mechanical cooling, making it very economical when conditions are suitable.