Free Cooling Retrofit

Adding ambient heat rejection to an existing hall so the compressors run for a fraction of the year — normally the largest energy saving available to a facility that is already built.

  • 1,673products across this application
  • 656verified manufacturers
  • 5equipment groups

WhatRejecting heat without a compressor

Free cooling uses ambient air to reject heat whenever it is cool enough, leaving the chillers idle. Indirect systems circulate glycol through outdoor dry coolers and transfer heat through a plate exchanger to the chilled water loop; direct systems bring outside air into the hall. Indirect is the usual retrofit choice because it does not expose IT equipment to outside air quality or humidity swings.

WhoWho buys it

Colocation operators under PUE commitments, enterprise facilities managers facing rising energy costs, and the mechanical contractors delivering upgrades into halls that must stay live throughout.

WhyWhy the chilled water temperature decides everything

The number of free-cooling hours you get is set by how warm you can let the chilled water run. Modern IT equipment tolerates a supply temperature far above the 6–7 °C that older halls were designed around; raising it to 18–20 °C can turn a marginal retrofit into one that free-cools for most of the year. In many halls, raising the water temperature is the actual project and the dry coolers merely follow from it.

HowRetrofitting into a live hall

Start by confirming what supply temperature the installed IT equipment genuinely tolerates, then calculate free-cooling hours against local weather data at that temperature. Size dry coolers for the changeover condition rather than the design day — oversizing here buys hours cheaply. Design the changeover control carefully, including the partial mode where ambient does some of the work and the chiller trims the rest, since that mode covers many of the annual hours. And plan the tie-ins so the hall never loses cooling: this is the part of the project that carries real risk.

Equipment this application needs

Dry Cooler Ambient heat rejection Dry Cooler349 The core of the retrofit. Size on changeover conditions, not the design day. Heat Exchangers Loop separation Heat Exchangers362 Plate exchangers between glycol and chilled water — the approach temperature here directly sets free-cooling hours. Axial Flow Fans Cooler fan arrays Axial Flow Fans672 EC drives so fan power falls with the cube of speed through the many part-load hours. Chilling Equipment Existing mechanical plant Chilling Equipment88 Retained for the hours ambient cannot cover; often replaced later once run hours collapse. Refrigeration & Heat Exchange Parts Valves & controls Refrigeration & Heat Exchange Parts120 Changeover valves and control integration — where retrofits usually go wrong.

What to check before you order

EC Motor 204
Part-load efficiency is the whole point; free cooling spends most hours at part load.
Variable Speed 106
Fan power falls with the cube of speed — the largest single saving in the system.
Energy Saving 1,205
The retrofit is justified on energy alone, so equipment efficiency is the business case.
Low Noise 654
Dry coolers usually go on a roof or in a yard with a night-time noise limit.
Corrosion Resistant 260
Outdoor equipment with a 15-year service expectation.

Products for this application

Questions buyers ask

How many hours a year will free cooling actually run?
It depends almost entirely on the chilled water temperature you can accept. At a traditional 6–7 °C supply the answer is modest even in a cool climate; at 18–20 °C — which modern IT equipment tolerates — it covers most of the year in temperate climates and a substantial share of night hours in warm ones. Calculate against local weather data at your actual target temperature before sizing anything.
Direct or indirect free cooling for a retrofit?
Indirect, in nearly all retrofits. It keeps outside air, its humidity and its contaminants away from the IT equipment, and it ties into an existing chilled water system without redesigning the hall’s air path. Direct systems can reach lower PUE but involve filtration, humidity control and a much larger intervention in a live building.
What is the main risk in a free cooling retrofit?
The tie-in to a live chilled water system. The mechanical equipment is straightforward; connecting it without ever interrupting cooling to a running hall is the part that needs careful staging, temporary provision and a tested fallback. Control changeover logic is the second area where retrofits underperform their projections.

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