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The Glass Pool · KAELTE

Free cooling & waste heat

Cooling — chiller, heat rejection, waste heat. Part of the glass family — like our glass BESS, biogas plant and CHP.

Free cooling & waste heat
Outside air → Dry cooler → Free cooling → Chilled water
Glass-box in 4 steps

Understand → See it live → What the AI does → Your benefit

Step 1 of 4
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Understand
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See it live
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What the AI does
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Your benefit

What is Free cooling & waste heat?

When the outside air is cool enough, the dry cooler can chill the water directly — the compressor stays largely off. This is the single biggest lever in cooling, and it hinges only on a clean release logic.

The other half is the waste heat: the condenser gives off heat anyway. Routing it into the hot water costs no additional generation — only the pipework to get there.

What is measured here

  • Outdoor temperature against the chilled water setpoint — the release condition
  • Free cooling hours per year (the real proof of success)
  • Compressor run time during hours with release granted
  • Waste heat quantity at the condenser where a tie-in exists

How we connect it — read-only

  • Outdoor and chilled water sensors over Modbus or the BMS.
  • Dry cooler over Modbus — fan power and operating mode.
  • Heat meter in the tie-in circuit where the waste heat is used.

Schematic (native, live)

Cooling — chiller, heat rejection, waste heat.

Outside airFree coolingChilled water

Overview: The Glass Pool → · Markets: pool markets →

Live —

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What the AI does

  • Checks whether the release actually takes effect — or whether the compressor runs despite cool air.
  • Counts the unused free cooling hours as a concrete backlog.
  • Routes the condenser waste heat into the hot water instead of rejecting it.
  • Shifts cooling demand into free-cooling windows where thermal mass allows.

Method proven on a live European reference aquatic center; presented anonymously.

Unused free cooling hours

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Estimate from metered / design values. Zero-grid-import windows are real (metered).

Standards & norms

What the rules require — Free cooling & waste heat

Grounded in DIN 19643, VDI 2089, DGfdB and the German Buildings Energy Act. Same knowledge base as the European reference site; presented anonymously.

At what outdoor temperature does free cooling work?

That depends on the chilled water setpoint and the dry cooler design. The higher the chilled water may run, the earlier in the year the release takes effect — only both together give the usable hours.

Basis: plant engineering

Why does free cooling often go unused?

Because the release is set too conservatively, or was never reviewed after commissioning. It only becomes visible when outdoor temperature and compressor run time are placed side by side.

Basis: plant engineering

Is condenser waste heat really usable?

It arises at a temperature level that suits hot water preheating. The question is not the potential but whether the pipework to get there exists.

Basis: plant engineering

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