Free cooling is an HVAC strategy that uses naturally cold outdoor air or water to cool a building, reducing or eliminating the need for mechanical refrigeration. It’s a powerful way to cut energy use, especially in cooler climates or during off-peak seasons.
Free cooling refers to a system design or operational strategy that leverages ambient outdoor air or water temperatures to assist or replace traditional mechanical cooling. Also known as economizer cooling, it reduces reliance on energy-intensive chillers or compressors by taking advantage of favorable environmental conditions.
There are a couple of ways to implement free cooling:
Air-Side Economizers – Introduce cool outdoor air directly into the HVAC system for space cooling when outside temperatures permit.
Water-Side Economizers – Use cooling towers and plate-and-frame heat exchangers to cool chilled water directly, bypassing the chiller during cooler periods.
Free cooling systems are especially valuable in data centers, schools, municipal buildings, and facilities with year-round or high-load cooling needs.
Lower Cooling Energy Costs – Uses nature instead of electricity for cooling when conditions allow
Improved HVAC System Longevity – Reduced runtime extends life of chillers and compressors
Supports Sustainability Goals – Cuts carbon emissions and aligns with ESG targets
Flexible Integration – Easily retrofitted into existing chilled water or air handling systems
Eligible for Incentives – May qualify for utility rebates as part of HVAC optimization
Quiet, Passive Cooling – Especially valuable for nighttime cooling in sound-sensitive environments
Scalable – Works in individual AHUs or central plant configurations
In traditional HVAC systems, cooling loads are met by mechanical chillers or DX systems that consume significant energy. Free cooling allows the system to bypass these components under specific conditions:
Air-Side: When outdoor air is sufficiently cool and dry, it is introduced into the building through modulating dampers, reducing or eliminating the need for compressor-based cooling.
Water-Side: Cooling towers reject heat into the atmosphere and chill water is routed through a heat exchanger, meeting cooling demand without activating the chiller.
Free cooling is often automated via sensors and controls that determine when conditions are optimal and switch between free cooling and mechanical cooling modes.
Free cooling reduces HVAC energy consumption by minimizing the use of chillers, compressors, and condensers. Energy savings stem from:
Reduced Compressor Run Time: Bypass mechanical cooling during cool outdoor conditions.
Lower Peak Demand Charges: Turn off during high-cost periods.
Optimized Seasonal Performance: Many systems can operate in free cooling mode for 30–50% of the year in temperate climates.
Better Load Matching: Control systems optimize transitions between free and mechanical cooling to match actual demand, avoiding overcooling or waste.
Facilities can see 10–40% energy savings depending on climate, operating hours, and system type.
Facilities in temperate or seasonal climates
Buildings with year-round cooling demand (labs, IT rooms, process equipment)
Properties with existing AHUs, chillers, or central plants
Sites looking to reduce carbon footprint without full equipment replacement
Evaluate system needs, weather patterns, and building profile
Determine integration method (air-side, water-side, or both)
Plan dampers, heat exchangers, sensors, and controls
Integrate hardware and smart controls into HVAC system
Test for operational efficiency and switch-over accuracy
Monitor seasonal performance and adjust thresholds
Utility programs often fund HVAC optimization and energy conservation measures (ECMs) that include free cooling.
Inovis can help secure:
Prescriptive rebates for economizer retrofits
Custom incentives for controls integration
Capital-light financing for broader HVAC upgrades
Many buildings already have the infrastructure needed for free cooling — they just aren’t using it. Inovis can assess your system and climate zone to determine your savings potential.
