Should You "Turn Up the Heat" in Your Data Center? The AI Era Changes the Answer
Raising data center temperatures used to be simple: align with updated guidance, squeeze out some efficiency, move on. That was in a world of lower densities and generous cooling overhead.
Today's AI-heavy racks are a different beast. High-density GPU loads are pushing air cooling to physical limits. Air doesn't move enough heat anymore, so any small efficiency win matters-but only if the environment is engineered first.
The old advice wasn't wrong-it was incomplete
Plenty of operators have tested warmer set points. Major clouds already run above the old 68-72°F band, and AI-first providers are trying even warmer rooms to cut cooling spend.
The facilities seeing real gains treat this as engineering, not a thermostat tweak. The fundamentals-airflow behavior, heat density, recirculation paths, and pressure balance-decide whether "hotter" is efficient or risky.
Engineer the room before you raise the set point
- Containment: Keep cold supply and hot exhaust fully separated (hot-aisle/cold-aisle containment still delivers the most predictable results).
- Pressure and path control: Balance supply/return, eliminate bypass air, and seal leaks.
- Airflow clarity: Know your paths end to end. Maintain elevated, predictable return temperatures.
- Load separation: Keep air-cooled and liquid-cooled gear from cross-contaminating airflow.
Do the groundwork, then adjust temperatures. That order matters.
Why warmer set points lower costs
Cooling plants-chillers and CRAHs/CRACs-pull a large share of facility power. In many sites, CRACs alone can consume 30-50% of total energy. Raise allowed IT inlet temperature from ~68°F (20°C) toward 77°F (25°C) or even 80.6°F (27°C), and the cooling equipment cycles less and works less hard.
That shows up directly in PUE. A move from 1.5 to 1.3 by optimizing set points alone can mean tens to hundreds of thousands of dollars saved annually in larger facilities. The efficiency gain is simply less mechanical work to reject heat.
Hardware age dictates your safe limits
Modern servers and switches are built to ASHRAE guidelines and generally run reliably at 80.6°F (27°C) or higher. Their sensors, firmware, and fan curves handle wider bands without drama.
Pre-2010 gear is another story. It was designed for cooler rooms and has less thermal headroom. Push it too hot and failures climb-think 0.5% annual failure jumping toward 2.0%-and any energy savings can be wiped out by downtime and replacements. Always check the oldest and most critical devices against the vendor spec before you touch the thermostat.
Older facilities also struggle with unmanaged airflow and recirculation. Raising temperatures there doesn't create efficiency-it exposes weak airflow control and makes hot spots worse.
There is no single "ideal" temperature
ASHRAE's recommended IT inlet band is 18-27°C (64.4-80.6°F). Many modern sites target the upper end-around 25°C (77°F)-because it balances savings with margin across enterprise gear.
Your "right" temperature depends on how consistently cold air reaches server inlets. If supply is below demand, recirculation exists, or pressure floats, running hotter adds risk fast. The reliable path is to engineer airflow first, then use CFD modeling to find the warmest set point that maintains stable, predictable inlets across all racks.
The goal isn't a magic number. It's the warmest stable operation that stays inside ASHRAE at the IT intake.
How to raise temperatures without getting burned
- Fix airflow first: Full containment, sealed gaps, balanced pressure, documented paths.
- Instrument heavily: Track GPU/CPU thermals, error rates, fan RPMs, PSU temps, and rack-level hot spots.
- Increase gradually: Bump 1-2°F (0.5-1°C) at a time, then hold. Watch telemetry and error trends for a full thermal cycle.
- Segment older gear: Apply stricter limits or isolate legacy racks that can't tolerate higher inlets.
- Model before you move: Run CFD to reveal recirculation, bypass air, and pressure issues before changes go live.
- Count total cost: Pair PUE savings with potential failure rates, maintenance, and hardware wear. Let the math decide.
AI racks change the thermal math
GPU-dense racks push air cooling to its limits. In mixed environments, keep liquid-cooled loads isolated and protect air-cooled rows from heat spillover. Maintain clear airflow boundaries and predictable returns, or the room runs out of headroom quickly.
Independent benchmarks and machine-level telemetry matter more now. As GPUs become some of your most expensive assets, validate that higher temperatures don't degrade reliability or throttle performance over time.
Bottom line
Raising data center temperatures still works-but only inside a properly engineered, monitored, and modeled environment. Contain the air, prove stability with CFD, move in small steps, and let data steer the ceiling.
If you want a primer on current thermal allowances, start with ASHRAE data center resources. For teams supporting AI-heavy estates and sharpening skills around infrastructure, you can also explore role-based learning paths at Complete AI Training.
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