TL;DR · 30-second read

The Short Version

Artificial intelligence data centers, the warehouse-sized buildings packed with computers, are running short of electricity. Many now build their own power plants on site.

Those generators give off a lot of leftover heat. Johnson Controls, a large maker of building cooling equipment, has published a design guide for machines that turn that heat into cooling, instead of powering the cooling with electricity.

The company says this can free up to 97 megawatts, enough electricity for tens of thousands of homes, to run more computers.

Johnson Controls on July 29, 2026 introduced an Absorption Chiller Reference Design Guide aimed at AI data centers that generate their own electricity on site. According to the company’s announcement, the design can unlock up to 97MW of additional AI capacity. It does this by using waste heat from on-site generation to drive the facility’s cooling, which frees electricity that conventional electric chillers would otherwise consume.

The guide is separate from the AI factory cooling reference design that Johnson Controls published earlier.

Executive Summary

A data center’s power supply is split between the computers themselves and everything that keeps them running, and cooling is one of the largest parts of that second share. Johnson Controls’ new guide targets that split. Absorption chillers produce chilled water using heat as their main energy input rather than an electric compressor. At a site that already burns fuel to make its own electricity, the exhaust and jacket heat from that generation can supply the chillers, so the electricity the cooling plant would have drawn can go to servers instead.

The headline figure is an upper bound: up to 97MW. Johnson Controls has not tied that number publicly to a specific site size, generator type or climate. The strategic point stands even so. As AI developers move generation behind the meter to avoid long grid-connection waits, the heat those plants produce becomes an asset to design around, not a byproduct to vent. By publishing a dedicated guide for that scenario, separate from its broader AI factory cooling design, Johnson Controls is treating on-site power as its own design category.

Why Waste Heat Becomes Compute Capacity

A power-constrained AI campus has a fixed electrical budget, and every megawatt spent on cooling is a megawatt not spent on GPUs. Conventional data center cooling relies on vapor-compression chillers, the same basic principle as a household refrigerator, which run large electric compressors. Absorption chillers work differently. They use a heat source, such as hot water, steam or engine exhaust, to drive a refrigeration cycle, and they need only modest electricity for pumps and controls.

Every fuel-burning generator, whether a gas turbine, a reciprocating engine or some fuel cell types, turns only part of its fuel into electricity. The rest leaves as heat. If that heat drives absorption chillers, much of the cooling load moves off the electrical budget and onto a thermal budget that was otherwise going to waste. The electricity released can power IT load. That is the mechanism behind Johnson Controls’ claim of up to 97MW of additional AI capacity. The pairing of generation with heat-driven cooling, long known as combined cooling, heat and power or trigeneration, is not new. What is new is framing it as a way to add AI compute capacity rather than as a way to save energy.

The people most affected are developers building campuses with behind-the-meter generation, and the investors financing them. For those projects, capacity is often capped by how much power the site can produce, not by floor space or chip supply. Recovering cooling power from waste heat raises the ceiling on revenue-generating compute without adding generators.

On-Site Power Changes the Cooling Question

Grid interconnection, the process of getting a utility to connect a large new load, has become one of the slowest steps in AI data center development. That has pushed developers toward generating their own electricity, at least as a bridge until grid power arrives. Once a site makes its own power, its cooling design no longer has to assume that all energy arrives as electricity. Heat is available too, and a reference design that shows how to use it addresses a question these projects now face.

This also explains why Johnson Controls kept the absorption guide separate from its earlier AI factory cooling reference design. A grid-fed facility and a self-powered facility start from different energy inputs, so a single template would fit one of them poorly. Splitting the guidance by power strategy lets engineers start from the case that matches their site.

What “Up To” Leaves Open

The benefit depends on several variables. It scales with how much recoverable heat the generation plant produces and at what temperature. It also scales with how much mechanical cooling the facility needs to begin with. Many new AI halls use direct liquid cooling with relatively warm water, which can reduce how many hours electric chillers must run. In those designs, the electricity an absorption system saves may be smaller than in a facility that relies heavily on chillers.

There are physical trade-offs too. Absorption chillers are typically larger and heavier than electric chillers of similar cooling output. They also reject more total heat, which usually means bigger cooling towers and possibly more water use. The cooling supply becomes tied to generator operation, so designers must plan for backup cooling when generators are down for maintenance. None of this undermines the concept. It does mean the up-to-97MW figure is a best case, and actual gains will vary from site to site.

Reference Designs as a Sales Channel

For an equipment maker, a reference design is both engineering guidance and a way to get specified early. Developers under schedule pressure tend to adopt pre-engineered architectures instead of designing mechanical plants from scratch, and the vendor behind the template benefits. Johnson Controls, which sells chillers under its York brand, is positioning itself at the point where cooling decisions become inseparable from power strategy. That link matters more as on-site generation spreads across AI projects.

Background

Johnson Controls is one of the largest suppliers of commercial heating, ventilation and air conditioning equipment. Its York-brand chillers are widely used in large buildings and data centers. As AI workloads have driven sharp increases in rack power density, cooling vendors have released AI-specific reference architectures. Johnson Controls had already published an AI factory cooling reference design before this absorption chiller guide.

Absorption cooling is a mature technology that has long been paired with on-site generation at universities, hospitals and industrial plants. Its relevance to data centers has grown as AI developers, facing slow grid connections, increasingly build their own generation and look for ways to get more compute out of every megawatt they produce.

Sources

Source: Johnson Controls introduces Absorption Chiller Reference Design Guide, unlocking up to 97MW of additional AI capacity from on-site power generation. Johnson Controls’ announcement of a reference design that uses on-site generation waste heat to cool AI data centers.