The short answer, and the levers that actually move it — written for CRE asset managers weighing a data-center cooling upgrade.
At the industry-average PUE of about 1.56 (Uptime Institute Global Data Center Survey 2024), roughly 36% of a data center's electricity goes to non-IT overhead — and cooling is its single largest slice. CRE owners cut it by raising set-points into ASHRAE's 18–27 °C recommended band, tightening airflow containment, and adding measured controls — not by rip-and-replace.
Where the energy actually goes
PUE — power usage effectiveness — is total facility power divided by the power that reaches the IT equipment. A PUE of 1.0 would mean every watt runs a server; the industry average has sat near 1.56 in 2024 and 1.54 in 2025, essentially flat for six years (Uptime Institute).
That flat average carries a precise implication. At PUE 1.56, IT equipment consumes 1 ÷ 1.56 ≈ 64% of the facility's electricity, which leaves about 36% as non-IT overhead — and in most halls, cooling is the largest component of that overhead, ahead of power distribution and lighting. For a CRE owner, that overhead is the addressable line item: the servers are the tenant's load, but the cooling that keeps them alive is the landlord's engineering problem.
The cheapest lever is the set-point, not a new chiller
The most over-looked lever costs nothing to install. ASHRAE Technical Committee 9.9 recommends a dry-bulb operating band of 18–27 °C (64.4–80.6 °F) with 40–60% relative humidity (ASHRAE TC 9.9 thermal guidelines). Many legacy halls still run at the cold end of that band — or below it — out of habit rather than requirement. Moving set-points toward the upper end of the recommended range directly reduces chiller and CRAC load and improves PUE, with no capital project attached.
The next tier of levers is airflow discipline: hot-aisle / cold-aisle containment, blanking panels, and sealed cable cut-outs stop cold supply air from short-circuiting back to the return before it does any work. These are low-capital retrofits with fast payback in most existing data halls, and they are prerequisites for any set-point increase to be safe.
"AI cooling optimization" is only worth what you can prove
Vendors increasingly pitch machine-learning control that promises to trim cooling energy automatically. The claim can be real — but for an asset manager it is only bankable when the savings are measured against a proper baseline, not asserted from a dashboard. That is the difference between a marketing number and a verifiable one. The discipline for it already exists: the IPMVP measurement-and-verification protocol was built precisely to separate the energy a control change actually saved from the weather and load noise around it.
Before you approve any data-center cooling upgrade, model it first. Our free AI-HVAC ROI calculator gives a first-pass payback estimate, and our companion read on data-center cooling AI optimization ROI covers what owners actually save versus what gets promised. For the verification side, see how automated M&V is replacing manual IPMVP.
Frequently asked
How much of a data center's energy is used for cooling? It varies by design and climate, but a useful upper bound comes straight from PUE: at the industry-average PUE of ~1.56, about 36% of total facility power is non-IT overhead, and cooling is typically its largest single component. Newer, well-run facilities push that overhead considerably lower.
What is a good PUE for a data center in 2026? The industry average has held near 1.54–1.56 for years (Uptime Institute). Modern, purpose-built facilities routinely operate well below that; a PUE approaching 1.2 is considered strong practice, though legacy and smaller sites remain higher.
Can you cut data-center cooling energy without replacing the chillers? Usually, yes. Raising set-points toward the top of ASHRAE's recommended 18–27 °C band, adding hot/cold-aisle containment, and sealing bypass airflow are low- or no-capital measures that reduce cooling load before any equipment is replaced.
Sources
- Uptime Institute Global Data Center Survey Results 2024 — industry-average PUE ~1.56.
- Uptime Institute Global Data Center Survey 2025 — ~1.54, flat for six years.
- ASHRAE TC 9.9 — Thermal Guidelines for Data Processing Environments — recommended 18–27 °C operating band.
Research compiled by the AISB agent fleet from primary sources; every claim verified against the public record. Cost figures are labeled industry estimates. Full source list available on request — hello@ai-smart-buildings.com.