AC Size for Server Room

Server Room Cooling

Server rooms require precise temperature control to prevent equipment overheating and ensure reliability. Unlike residential cooling, server room AC is primarily about removing equipment heat, not combating outdoor conditions.

Critical Differences from Standard AC

Server room cooling has unique requirements:

• 24/7 operation: Servers run continuously, so cooling must too
• Heat density: Much higher BTU per square foot than offices
• Precision: Tighter temperature tolerance required
• Redundancy: Backup cooling is essential
• Humidity control: Too dry causes static; too wet causes corrosion

Calculating Server Room Cooling

Equipment heat is the dominant factor:

• Formula: Total watts × 3.41 = BTU/hour
• 1 kW of equipment: 3,410 BTU
• 10 kW of equipment: 34,100 BTU = ~3 tons
• Add 20-30%: For room envelope gains and safety margin

Typical Server Power Consumption

• Small server: 200-500 watts
• Standard rack server: 500-1,000 watts
• High-performance server: 1,000-2,000 watts
• Full rack: 5,000-20,000 watts
• Network equipment: 100-500 watts per device
• UPS system: Adds 10-15% inefficiency heat

Sizing Examples

• Small closet (5 kW): 17,000 BTU + margin = 1.5-2 ton
• Server room (20 kW): 68,000 BTU + margin = 7-8 ton
• Small data center (100 kW): 340,000 BTU = 30+ tons

Temperature and Humidity Standards

ASHRAE guidelines for server environments:

• Recommended temp: 64-81°F (18-27°C)
• Optimal range: 68-75°F (20-24°C)
• Humidity: 40-60% relative humidity
• Max rate of change: 5°F (3°C) per hour

Best Practices for Server Cooling

• Hot aisle/cold aisle: Organize racks for efficient airflow
• Containment: Separate hot and cold air streams
• Redundancy: N+1 cooling capacity minimum
• Monitoring: Temperature sensors and alerts
• UPS for cooling: Cooling should have backup power
• Precision AC units: Better than standard comfort cooling

When to Call an Expert

For server rooms exceeding 10 kW or critical applications, consult a data center cooling specialist. Proper design includes airflow analysis, redundancy planning, and precision equipment selection beyond standard AC calculations.