What HVAC Systems Are Best for Data Centers? Precision Cooling Solutions

When your data center’s servers are generating thousands of watts of heat per rack, choosing the wrong HVAC system isn’t just costly, it’s catastrophic. A single cooling failure can lead to equipment damage, data loss, and downtime that costs businesses an average of $9,000 per minute.

At Camali Corp, we’ve spent over 35 years designing, building, and maintaining critical infrastructure systems for data centers across California. In our work with clients like Nike, Disney, and Harbor Freight Tools, we’ve seen firsthand how the right HVAC system can make or break a data center’s performance and profitability.

Why Data Center HVAC Systems Are Different

Data centers are not like regular commercial buildings. They run 24 hours a day, 7 days a week, and generate a lot of heat. Because of this, even small temperature changes can cause serious problems.

Cooling and ventilation use a lot of energy, about 40–50% of a data center’s total electricity. Choosing the right HVAC system is critical to keep equipment safe and control operational costs.

The challenge isn’t just keeping equipment cool. It’s maintaining precise environmental conditions while maximizing energy efficiency and ensuring redundancy. Modern data centers can house server racks generating 15-150 kW of heat each, requiring specialized cooling solutions that standard HVAC systems simply cannot handle.

The 5 Best HVAC Systems for Data Centers

1. Computer Room Air Conditioning (CRAC) Units

Best for: Small to medium data centers with moderate heat loads (up to 20-35 kW per rack)

CRAC units are the workhorses of data center cooling, using direct expansion refrigeration to maintain precise temperature and humidity control. These self-contained units include compressors, condensers, and evaporators, making them ideal for facilities that need reliable, independent cooling zones.

Key advantages:

• Precise temperature control (±1°F)
• Built-in humidity management
• Quick installation and commissioning
• Lower upfront costs compared to chilled water systems

Considerations: Higher energy consumption than CRAH systems and limited scalability for high-density applications.

2. Computer Room Air Handlers (CRAH) Units

Best for: Large data centers with centralized chilled water systems

CRAH units work with a central chilled water plant, using cooling coils and fans to distribute conditioned air throughout the facility. This approach offers superior energy efficiency and scalability for enterprise-level data centers.

Key advantages:

• 20-30% more energy efficient than CRAC units
• Excellent scalability for growing facilities
• Lower maintenance costs over time
• Better integration with building management systems

Considerations: Requires significant upfront investment in chilled water infrastructure and more complex installation.

3. Liquid Cooling Systems

Best for: High-density applications (50+ kW per rack) and AI/HPC workload

As server densities continue to increase, liquid cooling has become essential for managing extreme heat loads. These systems circulate coolant directly to server components or through rack-mounted heat exchangers.

Types of liquid cooling:

• Direct-to-chip cooling: Coolant flows directly over server processors to remove heat faster than air alone.
• Immersion cooling: Servers are placed in special liquid that absorbs heat directly, keeping equipment very cool.
• Rear-door heat exchangers: Liquid-cooled panels mounted on the back of racks to capture heat before it enters the room.

Key advantages:

• Handles heat loads up to 150+ kW per rack
• Superior energy efficiency (PUE as low as 1.03)
• Reduced noise levels
• Smaller facility footprint requirements

4. In-Row Cooling Units

Best for: High-density server environments with hot spot management needs

In-row cooling units are installed directly between server racks, providing targeted cooling where it’s needed most. This approach minimizes hot and cold air mixing while maximizing cooling efficiency.

Key advantages:

• Precise hot spot management
• Improved airflow efficiency
• Modular scalability
• Reduced bypass airflow

Considerations: Higher equipment costs and requires careful planning for maintenance access.

5. Hybrid Cooling Systems

Best for: Facilities with mixed workloads and varying density requirements

Hybrid systems combine multiple cooling technologies, such as traditional air cooling with liquid cooling for high-density racks. Providing flexibility and optimization for diverse computing environments.

Key advantages:

• Optimized cooling for different server types
• Future-proofing for evolving technology
• Energy efficiency across varied loads
• Risk mitigation through diversified systems

Critical Design Considerations

Temperature and Humidity Control

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommends maintaining data center temperatures between 64.4°F and 80.6°F (18°C to 27°C) with relative humidity between 40-60%. Exceeding these ranges can lead to:

• Too hot: Server throttling, component failure, reduced lifespan
• Too cold: Unnecessary energy consumption, condensation risk
• Too dry: Static electricity damage to sensitive components
• Too humid: Corrosion, short circuits, equipment failur

Redundancy Requirements

Data center cooling systems must include redundancy to prevent single points of failure. Common configurations include:

• N+1 redundancy: One backup unit for every N active units
• 2N redundancy: Complete duplicate systems on separate power feeds
• N+2 redundancy: Two backup units for enhanced protection

Airflow Management

Proper airflow design is crucial for cooling efficiency. Key strategies include:

• Hot aisle/cold aisle configuration: Arranging server racks so hot and cold air don’t mix, which improves cooling efficiency
• Containment systems: Physical barriers to prevent air mixing
• Raised floor systems: Underfloor air distribution
• Overhead return: Hot air extraction from ceiling plenums

Energy Efficiency and Sustainability

 

With data centers consuming approximately 1% of global electricity, energy efficiency is both an environmental and economic imperative. Key efficiency metrics include:

• Power Usage Effectiveness (PUE): Total facility power ÷ IT equipment power
  • PUE shows how efficiently your facility uses electricity for computing versus cooling
• Target PUE: Modern data centers should achieve PUE ≤ 1.3
• Best-in-class PUE: Advanced facilities achieve PUE ≤ 1.1

Emerging Efficiency Technologies

• Variable speed drives (VSDs): Adjust cooling capacity based on demand
• Free cooling: Using outside air when it’s cool enough to help lower data center temperatures without extra energy
• Waste heat recovery: Capture and reuse server heat for building heating
• AI-driven optimization: Using smart software to predict and adjust cooling needs automatically for better efficiency

Maintenance and Operational Excellence

Regular HVAC maintenance is critical for data center HVAC performance and reliability. Essential maintenance activities include:

Monthly:

• Filter inspections and replacements
• Temperature and humidity monitoring
• Airflow measurements
• Visual equipment inspections

Quarterly:

• Coil cleaning and inspection
• Refrigerant level checks
• Control system calibration
• Emergency system testing

Annually:

• Comprehensive system commissioning
• Ductwork inspection and cleaning
• Electrical connection tightening
• Performance optimization analysis

Cost Considerations and RO

While precision cooling systems require significant upfront investment, the total cost of ownership often favors higher-efficiency solutions:

Initial costs:

• CRAC units: $15,000-$50,000 per unit
• CRAH systems: $25,000-$75,000 per unit (plus chilled water plant)
• Liquid cooling: $50,000-$200,000 per rack
• In-row cooling: $20,000-$60,000 per unit

Operational savings:

• Energy costs: 20-40% reduction with efficient systems
• Maintenance costs: Lower with properly designed systems
• Equipment lifespan: Extended through optimal environmental control
• Downtime prevention: Avoiding costly outages

Future-Proofing Your Data Center

As computing demands evolve, your cooling infrastructure must adapt. Consider these trends:

• AI and machine learning workloads: Requiring higher cooling densities
• Edge computing: Demanding smaller, more efficient cooling solutions
• Sustainability mandates: Driving adoption of renewable energy and efficient cooling
• Liquid cooling adoption: Becoming standard for high-performance computing

Making the Right Choice for Your Facility

Selecting the optimal HVAC system depends on several factors:

1. Heat density: Current and projected kW per rack
2. Facility size: Total square footage and rack count
3. Budget constraints: Capital and operational expenditure limits
4. Redundancy requirements: Uptime objectives and risk tolerance
5. Future growth: Scalability and expansion plans
6. Local climate: Opportunities for free cooling and efficiency optimization

Expert Implementation Matters

The best HVAC system is only as good as its design and installation. Working with experienced data center specialists ensures:

• Proper system sizing and configuration
• Optimal airflow design and containment
• Reliable redundancy and backup systems
• Efficient commissioning and startup
• Ongoing maintenance and optimization

At Camali Corp, our team brings decades of experience in data center HVAC design, installation, and maintenance. We understand that every facility has unique requirements, and we work closely with clients to develop customized solutions that balance performance, efficiency, and cost-effectiveness.

Choosing the Right HVAC System for Your Facility

Choosing the right HVAC system for your data center is a critical decision that impacts performance, reliability, and operational costs for years to come. Whether you need traditional CRAC units for a smaller facility or advanced liquid cooling for high-density AI workloads, the key is working with experienced professionals who understand the unique challenges of data center environments.

Don’t let cooling system failures put your critical operations at risk. Contact Camali Corp today to discuss your data center HVAC requirements and discover how our proven expertise can help you achieve optimal performance, efficiency, and reliability.

Frequently Asked Questions

What is the ideal temperature range for a data center?

ASHRAE recommends maintaining temperatures between 64.4°F and 80.6°F (18°C to 27°C) with relative humidity between 40-60% for optimal equipment performance and longevity.

How do I calculate cooling requirements for my data center?

Cooling load calculation should account for IT equipment power consumption, lighting, human occupancy, and heat gain from building envelope. Each watt of IT power typically requires 1-1.3 watts of cooling capacity, depending on system efficiency.

What’s the difference between CRAC and CRAH units?

CRAC units use direct expansion refrigeration with built-in compressors, while CRAH units use chilled water from a central plant. CRAH systems are typically more energy-efficient but require higher upfront investment in chilled water infrastructure.

When should I consider liquid cooling?

Liquid cooling becomes necessary when rack densities exceed 20-30 kW, particularly for AI, machine learning, and high-performance computing applications. It’s also beneficial for facilities seeking maximum energy efficiency and minimal space requirements.

How often should data center HVAC systems be maintained?

Critical components should be inspected monthly, with comprehensive maintenance performed quarterly. Annual commissioning and optimization ensure peak performance and identify potential issues before they cause failures.