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 thousands of dollars 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 of 20-35 kW per rack, CRAC units are the workhorses of data center cooling. They use 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.
CRAC units offer precise temperature control within ±1°F, built-in humidity management, and fast installation at lower upfront costs compared to chilled water systems. However, they consume more energy than CRAH units and are less scalable for high-density applications.
2. Computer Room Air Handlers (CRAH) Units
Designed for large data centers with centralized chilled water systems, CRAH units use cooling coils and fans to distribute conditioned air efficiently. They are 20-30% more energy efficient than CRAC units and provide excellent scalability for growing facilities, while integrating smoothly with building management systems.
The trade-off is that CRAH units require significant upfront investment in chilled water infrastructure and a more complex installation process.
3. Liquid Cooling Systems
Liquid cooling is essential for high-density applications exceeding 50 kW per rack, including AI and HPC workloads. These systems circulate coolant directly to server components or through rack-mounted heat exchangers. Methods include direct-to-chip cooling, immersion cooling, and rear-door heat exchangers.
Liquid cooling can handle heat loads above 150 kW per rack, improve energy efficiency with PUE as low as 1.03, reduce noise levels, and allow smaller facility footprints. This makes it ideal for extreme heat environments where traditional air systems fall short.
4. In-Row Cooling Units
In-row cooling units sit directly between server racks, targeting hot spots to improve airflow efficiency and minimize mixing of hot and cold air. This approach allows modular scalability and precise cooling where it is most needed.
While effective, in-row units come with higher equipment costs and require careful planning for maintenance access.
5. Hybrid Cooling Systems
Hybrid cooling combines multiple technologies, often pairing traditional air cooling with liquid cooling for high-density racks. These systems provide optimized cooling for diverse server types, improve energy efficiency across varying loads, and offer flexibility for evolving technology. Hybrid systems also reduce risk by diversifying cooling strategies within a single facility.
Critical Design Considerations
Temperature and Humidity Control
Maintaining proper temperature and humidity is vital for reliable data center operations. ASHRAE recommends keeping server inlet air temperatures between 64.4°F and 80.6°F (18°C to 27°C) and managing relative humidity around 40-60%. Temperatures that are too high can cause servers to throttle, shorten component lifespans, or trigger failures, while overly cold conditions waste energy and increase condensation risks. Humidity outside the recommended range can also harm equipment: low humidity increases the chance of static electricity damage, and high humidity can lead to corrosion, short circuits, and system failures. Careful environmental control protects both equipment and operational efficiency.
Redundancy Requirements
Redundancy is essential to prevent a single point of failure in cooling systems. Data centers often deploy backup units so that if one system fails, others maintain environmental stability. 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
Efficient airflow design reduces energy consumption and keeps systems within safe operating limits. Hot aisle/cold aisle layouts separate warm exhaust air from cool supply air, while containment solutions further prevent mixing and improve cooling efficiency. Raised floors and overhead return plenums are commonly used to optimize airflow distribution, ensuring conditioned air reaches server intakes and hot air is effectively removed from the environment. Proper airflow planning is as important as system capacity for maintaining stable temperatures.
Energy Efficiency and Sustainability
Data centers consume roughly 1% of global electricity, making energy efficiency a critical environmental and economic concern. A key metric, Power Usage Effectiveness (PUE), compares total facility power to IT equipment power, showing how much energy goes to computing versus cooling. Modern facilities aim for a PUE of 1.3 or lower, with best-in-class centers reaching 1.1.
Emerging technologies further improve efficiency. Variable speed drives adjust cooling based on demand, free cooling uses outside air when conditions allow, and waste heat recovery captures server heat for other building needs. AI-driven optimization software can predict cooling requirements and adjust systems automatically, reducing energy consumption while maintaining safe operating conditions.
Maintenance and Operational Excellence
Regular HVAC maintenance is essential for reliable data center performance. Monthly checks should include inspecting and replacing filters, monitoring temperature and humidity, measuring airflow, and visually assessing equipment for signs of wear or damage. Quarterly maintenance involves cleaning and inspecting coils, verifying refrigerant levels, calibrating control systems, and testing emergency systems to ensure proper operation. Annual maintenance focuses on comprehensive system commissioning, inspecting and cleaning ductwork, tightening electrical connections, and analyzing overall performance to optimize efficiency and reliability.
Cost Considerations and ROI
Precision cooling systems require a significant upfront investment, but total cost of ownership often favors higher-efficiency solutions. Initial costs vary by system type: CRAC units typically range from $15,000 to $50,000 per unit, while CRAH systems cost $25,000 to $75,000 per unit, not including the chilled water plant. High-density solutions like liquid cooling can range from $50,000 to $200,000 per rack, and in-row cooling units usually cost between $20,000 and $60,000 each.
Operational savings are a major factor in ROI. Efficient cooling systems reduce energy costs by 20-40%, lower ongoing maintenance expenses, extend the lifespan of IT equipment through optimal environmental control, and prevent costly downtime by maintaining consistent performance. Choosing higher-efficiency systems may have a higher initial price, but the long-term financial and operational benefits often outweigh the upfront investment.
Future-Proofing Your Data Center
As computing demands evolve, data center cooling systems must evolve to keep pace. AI and machine learning workloads increase cooling density requirements, while the rise of edge computing drives the need for smaller, highly efficient solutions. Sustainability mandates are encouraging the adoption of renewable energy and energy-efficient cooling technologies. At the same time, liquid cooling is becoming a standard choice for high-performance computing, offering superior heat management and future scalability.
Making the Right Choice for Your Facility
Selecting the optimal HVAC system depends on several factors:
- Heat density: Current and projected kW per rack
- Facility size: Total square footage and rack count
- Budget constraints: Capital and operational expenditure limits
- Redundancy requirements: Uptime objectives and risk tolerance
- Future growth: Scalability and expansion plans
- Local climate: Opportunities for free cooling and efficiency optimization
Expert Implementation Matters
Even the most advanced HVAC system performs only as well as its design and installation. Working with experienced data center specialists ensures proper system sizing, optimized airflow and containment, reliable redundancy, efficient commissioning, and ongoing maintenance.
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.
