A server room air conditioning failure can cause thousands of pounds of equipment damage and business disruption within hours. Getting server room cooling right — with the correct system type, proper sizing, adequate redundancy and regular maintenance — is one of the most important infrastructure decisions for any business that runs its own IT equipment. Here is what you need to know.
Why Standard Comfort Cooling Is Not Enough
Standard wall-mounted split systems designed for office comfort cooling are not appropriate for server rooms. Here is why:
Continuous operation: Server room cooling must run 24 hours a day, 365 days a year. Standard comfort cooling units are designed for intermittent operation — typically 8-12 hours per day. Running them continuously accelerates wear on compressors and fan motors and typically results in premature failure within 2-3 years.
Humidity control: Servers and network equipment are sensitive to both high humidity (causes condensation on circuit boards) and low humidity (causes static discharge). Standard comfort cooling units cool air but do not actively control humidity. Precision cooling systems maintain both temperature and humidity within specified ranges.
Sensible heat ratio: Standard cooling units are optimised for mixed sensible (temperature) and latent (humidity) cooling — i.e., cooling rooms occupied by people. Server rooms generate almost entirely sensible heat — the equipment produces heat but not moisture. A precision cooling unit with a high sensible heat ratio is significantly more efficient for server room cooling than a standard unit.
Airflow direction: Servers need cool air delivered to the front (intake) and warm air extracted from the rear. Standard wall-mounted units deliver air horizontally from the wall — not appropriate for a properly organised server room with hot aisle/cold aisle layout.
Precision Cooling Options for Server Rooms
Close-coupled precision cooling units: Floor-standing or rack-mounted units positioned within or adjacent to the server room, delivering cool air directly to the server intake. Brands include Stulz, Airedale, Emerson and Vertiv. Higher capital cost than standard units but designed for continuous operation, humidity control and high sensible heat ratio. The correct choice for any server room with significant heat load.
In-row cooling: For larger data centre environments, cooling units deployed within server rows deliver air directly to equipment intakes at the point of need. Very efficient for high-density environments.
Standard precision split systems: For smaller server rooms with modest heat loads, a high-quality inverter split system with 24/7 rated components is sometimes appropriate. We specify systems with commercial-grade compressors and fans specifically rated for continuous operation, combined with a separate humidity monitoring and alerting system.
Sizing Server Room Cooling
Server room cooling is sized on heat load rather than room dimensions. The heat load is determined by the total power consumption of all equipment in the room — approximately 95% of electrical energy consumed by IT equipment is converted to heat. A room with servers consuming 10kW of electrical power generates approximately 9.5kW of heat that must be removed.
Always add headroom for future expansion — installing a system sized exactly for current load leaves no capacity for additional equipment. We typically recommend sizing at 125-150% of current heat load.
Redundancy — N+1 as Standard
For any mission-critical server room, N+1 redundancy — one additional cooling unit beyond the minimum required — is the industry standard. If one unit fails, the redundant unit takes the full load while repairs are arranged. We design server room cooling systems with N+1 redundancy as standard for commercial clients.
Monitoring and Alerting
Temperature and humidity sensors with remote alerting — ideally integrated with the business’s IT monitoring system — provide early warning of cooling problems before they cause equipment damage. We install monitoring systems alongside all server room cooling installations.
Cost
A properly specified server room cooling solution for a small-to-medium business — precision cooling unit, monitoring, N+1 redundancy — typically costs £5,000-15,000 depending on heat load and redundancy requirements. This compares favourably to the cost of IT equipment damage and business disruption from a single cooling failure.
Call 07833 053749 or contact us for a server room assessment. We cover East Grinstead, Surrey, Sussex and South London.