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Cooling Capacity: Everything You Need to Know

Cooling Capacity

It’s no secret that data centers use quite a lot of electricity. Considering the massive computing power they can fit onto a single data floor and the cooling infrastructure required to maintain an ideal operating environment, data centers consume approximately 3% of the world’s electricity.

With the growth of hyper-scale facilities, power usage is likely to keep increasing despite the improvements being made in efficiency.

By understanding cooling capacity, you can cool your data center IT devices much more efficiently. To help prevent any server or equipment issues, you need to keep your data center operating at the correct temperatures through the use of cooling systems.

Related: What Data Centers Do and Why

What is Cooling Capacity?

At its core, cooling capacity is a system’s ability to remove heat from the space around it. Cooling capacity is typically measured in watts (W) but can also describe how much water at a certain temperature can be frozen in a specific amount of time via tons. The British Thermal Unit (BTU) is the temperature required to increase a pound of water by one degree Fahrenheit. BTUs per hour show how much heat a unit can dissolve in an hour.

You can also reference cooling capacity via tonnage. For example, talking about a 2-ton air conditioner, the “2-ton” references its cooling capacity, not its physical weight. In this application, a “ton” represents how much cooling power a ton of ice offers in a 24-hour period. For example, one ton of refrigeration equals 200 BTU/minute and 211 kJ/minute.

A one-ton AC uses approximately 1,200 watts of electricity per hour, and the average electricity cost in the US is $0.12/kWh. Running that one-ton AC for a 24-hour period would use 28,800 watts, costing about $3.46.

Measuring Data Center Heat Output

Above, we mentioned the measurement units commonly used in heating and cooling, but let’s look at how to make any conversions you might need to know:

  • Converting BTU/hour into watts: Multiply by 0.293
  • Converting tons into watts: Multiply by 3.41
  • Converting watts into BTU/hour: Multiply by 3.41
  • Converting watts to tons: Multiply by 0.000283

The power used by IT equipment’s AC mains is almost completely converted into heat, and the power used by data lines is negligible. So, the thermal output of your equipment is equal to its power consumption. The exception is VoIP routers—their heat output is lower than their power consumption because the power they consume often gets sent to remote terminals.

Data Center Cooling Capacity

Data Center Cooling Capacity Load

Heat generation is a side-effect of running electrical equipment. In data centers, excessive heat can damage servers and other equipment. If temperatures get too high, your servers might shut down, and regularly operating at high temperatures can shorten their lifespans.

High humidity is a similar problem, but more on that later.

Determining data center air cooling equipment sizes involves considering factors like:

  • The cooling load (or heat output) of your equipment
  • The heat output of the lighting
  • The heat output of your personnel
  • The cooling load of the building
  • Oversizing required because of humidification effects
  • Oversizing for redundancy
  • Oversizing for future growth

Related: Understanding Data Center Infrastructure

Determining the Overall Heat Output of a Data Center

To fully understand your data center’s cooling capacity load, you need to first calculate the total heat output of your equipment. This includes lighting, people, UPS systems, and every piece of IT equipment.

The heat output of your power distribution and UPS systems consist of both a fixed loss and one that is proportional to the data center’s operating power. Because the losses are relatively consistent between all models and brands of this type of equipment, you can estimate the values without seeing any significant errors in calculations.

While air conditioners don’t contribute to the thermal load of a data center (because it releases the heat outdoors), the heat they produce does impact their efficiency. It’s essential to account for this loss when sizing a unit.

Here’s how to calculate the heat output for your data center:

  • Add up all of the load power from your IT equipment. This number is your heat output.
  • Use this formula for a battery-powered UPS system: [0.04 x Power system rating] + [0.05 x Total IT load power.] If you use a redundant system, do not include its capacity.
  • For a power distribution system, use this formula: [0.01 x Power system rating] + [0.02 x Total IT load power.]
  • To calculate your lighting’s heat output, use the floor area of the building and multiply the square footage by 2.0 or the square meters by 21.53.
  • To calculate the amount of heat produced by your personnel, multiply the maximum amount of people in the facility at once by 100.

Adding up the above calculations will give you the data center’s total heat source output.

Related: Data Center Efficient Power Management

The Effect of Humidification on Data Center Cooling Capacity

When calculating cooling requirements, you need to account for supplemental humidification. AC systems both control humidity and remove heat. Ideally, the system would keep a constant amount of water in the air and eliminate the need for additional humidification. But, because most AC systems create a significant amount of condensation, they decrease humidity. Because of that, you’ll need to supplement the data center with humidification equipment, but that also adds to the heat load.

For small systems that have a ducted air return, you don’t have to account for humidity. However, for larger systems that mix the air, you might need to oversize your AC unit by up to 30 percent.

Outdoor Data Center Generators for Cooling

Determining Cooling Capacity With Alterum

Properly calculating your data center’s cooling requirements is critical to reliable, cost-effective operations. Excessive heat or humidity can reduce your equipment’s lifespan and cause devices to shut down. You need to account for all of your equipment’s cooling load and heat sources.

Working with a data center expert like Alterum is a smart strategy to ensure optimal, efficient cooling of your data center. We offer the best, modern cooling technologies and can help design, install, and maintain the entire cooling system. 

Interested in learning about how we can optimize your data center cooling system? Get in touch with our data center cooling experts today!

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