Precision Cooling for Data Centers | CRAC, In-Row, Chilled Water & Free Cooling

Precision cooling is not a luxury or an optional upgrade. It is the difference between a data center that runs 24/7 without interruption and one that suffers costly downtime, degraded hardware, and an uncontrolled electricity bill. At Noxtel we design, install, and maintain cooling systems purpose-built for critical environments.

Why office air conditioning doesn’t work in a data center

A split unit or office cassette is designed for human comfort: it cools spaces where the thermal load is low and variable. A data center generates heat that is constant, concentrated, and massive. A full rack can dissipate between 5 and 30 kW — and a full aisle, much more. Conventional air conditioning cannot handle that load on a sustained basis.

• Sensitivity vs. precision. A comfort unit holds ±3°C of tolerance. Servers need ±0.5°C. Every degree above the optimal range shortens hardware life.
• Humidity control. Domestic air conditioning does not manage humidity. In a data center, low humidity generates static electricity; high humidity causes condensation and corrosion. Both destroy equipment.
• Continuous operation. Comfort units are not designed to run 8,760 hours a year at full load. They degrade, lose efficiency, and fail when you least expect it.
• Directed airflow. Precision cooling delivers cold air exactly where it is needed and extracts heat at the source. A split unit simply blows air into a room.

If you have office air conditioning in your data center, you are already losing money — in electricity consumption, in asset degradation, and in downtime risk.

Types of precision cooling systems

There is no single answer. The right system depends on your data center density, your location’s climate, your energy budget, and your growth plan. These are the main types we install and maintain:

CRAC (Computer Room Air Conditioning)

CRAC units are the traditional solution for low-to-medium density data centers. They are placed at the room perimeter and deliver cold air through a raised floor. Hot air returns through the top. They are reliable, well-understood, and relatively simple to maintain.

• Ideal for densities up to 5-8 kW per rack.
• Require a well-sealed raised floor to prevent cold/hot air mixing.
• Easy to maintain with widely available spare parts.
• Less efficient at high densities because air travels long distances before reaching the racks.

In-Row

In-row systems are placed directly between the racks, eliminating the distance between the cold source and the thermal load. They capture hot air on the spot and cool it before it mixes with the rest of the room. They are the natural fit for medium and high densities.

• Handle densities of 8 to 25 kW per rack without issue.
• Faster response time: the sensor detects temperature changes and adjusts in seconds.
• Reduce air mixing because they act close to the source.
• Scalable: add units as you grow.

Chilled Water

Chilled water systems use external chillers that cool water and pump it to units inside the data center. Water carries heat far more efficiently than air, which makes them ideal for large, high-density installations.

• Capable of handling densities above 30 kW per rack.
• Chillers can sit outside the data hall, freeing interior space.
• Very efficient at scale — the larger the data center, the better the cost/performance ratio.
• Require piping, pumps, and more specialized maintenance.

Free Air Cooling (Outside Air Economization)

If your data center sits in a temperate or cold climate, you can use outside air directly to cool the room for a large part of the year. It is not a complete solution — you still need backup for the warm months — but it can cut cooling energy consumption by 40-70%.

• Maximum energy efficiency: outside air is free.
• Requires high-efficiency filters for dust, particulates, and gaseous contaminants.
• Works best in climates with annual average temperatures below 18°C.
• Can be combined with other systems in a hybrid configuration.

Temperature and humidity control

ASHRAE TC 9.9 defines the recommended ranges for IT equipment environments. Classes A1 and A2 — the most common in data centers — recommend keeping intake air temperature between 18°C and 27°C, with a dew point between -9°C and 15°C (or relative humidity between 20% and 80%).

We do not recommend operating at the extremes. A target of 21-23°C with 40-50% relative humidity gives you safe margin against load spikes and momentary cooling system faults.

Precise control of these variables requires:

• Sensors at the right point. Temperature is measured at the rack intake, not at the CRAC return. Measuring at the wrong location produces misleading readings.
• Continuous monitoring with alerts. Checking a panel once a day is not enough. You need 24/7 monitoring with configured alert thresholds and automatic notification.
• Automatic adjustment. Modern systems adjust fan speed, refrigerant flow, and valve position in real time based on current load.

Aisle containment: hot aisle / cold aisle

Mixing cold air with hot air is the most expensive mistake you can make in a data center. If you do not separate the flows, your cooling system works harder than it needs to, consumes more energy, and still does not cool properly. Aisle containment fixes this:

• Cold aisle containment. The aisle where cold air enters (under the raised floor) is enclosed with doors and a ceiling. Cold air only reaches the racks — it does not disperse into the room.
• Hot aisle containment. The aisle where hot air exits is enclosed. Heat is contained and channeled directly back to the CRAC return without mixing with cold air.

Which one is better? It depends on your installation. In general, hot aisle containment works better with ceiling returns, and cold aisle containment with raised floors. Both improve cooling efficiency by 15% to 30% over an uncontained room. Without containment, you are paying to cool the same air twice.

Impact on PUE

PUE (Power Usage Effectiveness) measures how much total energy your data center consumes for every kW delivered to IT. A PUE of 1.0 would mean all energy goes to servers — an impossible ideal. The industry average sits around 1.58. The best data centers run 1.1-1.2.

Cooling usually accounts for 30% to 40% of total data center energy consumption. It is, by far, the largest area for improvement.

• A poorly configured CRAC system without aisle containment can push PUE above 2.0.
• The same room with containment and tuned airflow can bring it down to 1.5.
• Adding free cooling in a favorable climate can get you close to 1.3.
• An integrated design with chilled water, containment, and dynamic load management can reach 1.2.

The difference between a PUE of 2.0 and one of 1.3 is not an academic number. In a data center with 1 MW of IT load, it means saving 700 kW every hour — hundreds of thousands of dollars a year. Precision cooling pays for itself.

What we do at Noxtel

• Thermal audit. We measure real temperatures, map hot spots, and quantify inefficiencies in your current installation.
• System design. We select the right technology, capacity, and topology for your density, budget, and growth plan.
• Installation and commissioning. We install, configure, calibrate, and validate with load testing before handover.
• Preventive maintenance. Scheduled inspections, filter cleaning, sensor verification, and seasonal adjustment to keep performance optimal all year.
• 24/7 monitoring. Monitoring platform with automatic alerts, real-time dashboards, and periodic efficiency reports.

Do you know how much poor cooling is costing your data center?

If you do not have a recent thermal study, you are guessing. Our DPI-DC service analyzes your full infrastructure — power distribution, cooling, cabling, physical security, and asset management — and gives you a concrete plan with priorities, timelines, and ROI.

Request a DPI-DC assessment