Precision Cooling / Australia
Server Room Air ConditioningSizing, Options and Cost
Direct answer
Server room air conditioning is dedicated precision cooling sized to the room's IT heat load in kilowatts, not its floor area, and held between 18 and 27 degrees Celsius year round under ASHRAE TC 9.9 rather than run to a comfort setpoint. A comfort split system delivers only 65 to 75 per cent of its capacity as useful sensible cooling. A precision unit delivers 95 to 100 per cent, which is why the two are not interchangeable.
Indigi Power and Cooling supplies, installs and maintains room-based, wall-mounted, in-row and specialised server room cooling from 2.5kW to 250kW across Australia. Call 1800 046 344.
Start here
How big is the room, actually
Most people arriving here have one of three problems, and they need very different answers. Find yours before reading the engineering.
| What you have | Typical IT load | What you probably need |
|---|---|---|
| A comms cupboard with one or two racks | 1.5 to 7kW | A wall-mounted or ceiling-mounted precision split rated for continuous duty, roughly 3 to 7kW. Unit cost usually $8,000 to $15,000. This is the most common Australian situation and the one most often solved wrongly with a domestic split system |
| A dedicated server room, a few racks | 7 to 20kW | A larger wall-mount or a small floor-standing precision unit, and this is the point where a second unit for redundancy starts to be worth the money rather than a luxury |
| A proper server room or small data hall | 20kW and above | Room-based downflow or upflow CRAC, or chilled water if the building already has a plant. In-row once any single rack passes about 10kW |
If your load is under about 1.5kW you may get away with ventilating into an adjacent space, but only if that space is itself conditioned around the clock. Building air conditioning that shuts off at 6pm does not count.
The core mistake
Why a normal splitfails in a server room
A comfort air conditioner is engineered for people. People produce moisture, so a comfort unit is built to remove latent heat as well as sensible heat, and it is built to cycle. Servers produce essentially no moisture and never stop. Four things go wrong when you point a comfort unit at a rack.
Wasted capacity. A comfort split runs a sensible heat ratio of about 0.65 to 0.75. A nominal 7kW unit therefore delivers roughly 4.5 to 5.2kW of useful cooling against an IT load. A precision unit at 0.95 to 1.0 delivers close to its full nameplate.
Over-dehumidification. With no moisture to remove, the coil keeps stripping the little that is there. Relative humidity drifts below 30 per cent and static discharge risk climbs.
Short cycling and early failure. Comfort units are rated for intermittent duty. Continuous operation at partial load hammers the compressor. Three to five years is a common life in this application, against twelve to fifteen for a properly specified precision unit.
No winter operation. A standard condenser will not run reliably below roughly 15 degrees Celsius ambient, and your server room still needs cooling in July in Melbourne or Canberra. Low ambient kit and head pressure control are standard on precision units and absent on most comfort splits.
Side by side
Comfort unitor precision cooling
Standard
split
- Sensible heat ratio 0.65 to 0.75, a third wasted
- Intermittent duty, not rated for 24/7
- Broad comfort temperature range only
- Over-dries a room that has no moisture load
- Usually will not run below 15 degrees ambient
- Typical life in this duty: 3 to 5 years
Precision
cooling
- Sensible heat ratio 0.95 to 1.0, near full nameplate
- Designed for continuous 24/7/365 operation
- Tight control, plus or minus 1 degree
- Active humidity control against static and condensation
- Winter kit available to below 0 degrees
- Typical life in this duty: 12 to 15 years and beyond
Sizing
How to size it properly
Measure the real IT load in kW
Read it off the UPS output display or a rack PDU, not off equipment nameplates. Nameplate ratings are typically 40 to 60 per cent above actual draw, and sizing on them is the most common way an Australian comms room ends up with double the cooling it needs and a unit that short cycles because of it.
Add the UPS and non-IT losses
A UPS in the room rejects its inefficiency as heat. A double conversion UPS at 94 per cent efficiency carrying 10kW adds roughly 0.6kW. Add lighting and any transformers sharing the space.
Add the building envelope
Add 10 to 20 per cent for walls, ceiling, solar gain and infiltration. Take the upper end for a west-facing external wall, a colorbond roof, or a room in Darwin, Perth or western Sydney.
Apply your redundancy strategy
If you want N plus one, each unit must be able to carry the full calculated load on its own. Two units at half load each is not N plus one, it is a room with two single points of failure.
Add growth headroom
Allow 20 to 25 per cent for the next three to five years of rack additions, or you will be back here. Useful conversion while you work: 1kW of cooling equals 3,412 BTU/hr, which is why small wall-mount IT units cluster around the 10,000 to 12,000 BTU mark.
Worked example
An 8kW comms room in Brisbane
Measured IT load of 8kW, a 10kVA double conversion UPS in the room, LED lighting, one external west wall, and plans for two more racks.
| Heat source | Basis | Load |
|---|---|---|
| IT equipment | Measured at UPS output | 8.0kW |
| UPS losses | 6 per cent of 8kW | 0.5kW |
| Lighting and ancillary | LED, 20 square metres | 0.2kW |
| Envelope and solar gain | 18 per cent, west wall, Brisbane | 1.6kW |
| Subtotal, present day | Sum of the above | 10.3kW |
| Growth allowance | 25 per cent, two more racks | 2.6kW |
| Design load per unit for N plus one | Each unit carries the full load | 12.9kW, so two units of 13kW |
Broad sanity check against the calculation: small server rooms 5 to 20kW, medium comms and server rooms 20 to 50kW, larger rooms and small data halls 50 to 90kW, data centres 100kW and above with N plus one or 2N redundancy.
The common case
A room like this is the majority of the Australian installed base. Two or three racks, a UPS, and a single wall mounted unit doing all the work. It is a perfectly good arrangement provided the unit is a precision unit sized on measured load, and provided somebody has decided in advance what happens when it stops.
Measure at the rack inlet, not at the wall. A room reading 22 degrees at the door can be delivering 34 degrees to the top of a poorly managed rack, and the equipment only cares about the second number.
Setpoints
Temperature and humidity to actually set
The reference every Australian consultant works to is the ASHRAE TC 9.9 thermal guideline for data processing environments.
| Parameter | Target | In practice |
|---|---|---|
| Recommended dry bulb | 18 to 27 degrees Celsius | Measured at the rack inlet, not at the wall thermostat and not in the return air path |
| Allowable, Class A1 equipment | 15 to 32 degrees Celsius | A short term tolerance, not a design target. Above 32 at the inlet, throttling and error rates rise and warranty positions can be affected |
| Recommended humidity | Dew point minus 9 to 15 degrees Celsius, up to 60 per cent RH | Most Australian comms rooms are controlled to a 40 to 60 per cent RH band |
| Rate of change | No more than 5 degrees Celsius per hour | Which is why a room that has lost cooling should be brought back gradually rather than shocked |
A setpoint of 18 degrees is not safer than 24 degrees, it is just more expensive. Every degree lower costs energy and buys nothing while inlet temperatures sit inside the recommended band.
Choosing
Options by heat load
Once you have a design load in kW, the unit type follows from it.
| Option | Load range | Best fit | Watch out for |
|---|---|---|---|
| Portable or spot cooler | Up to 3kW | Temporary cover during a failure or a fit-out | Needs a hot air discharge path and condensate handling. Not a permanent solution, whatever the retailer says |
| Precision wall-mount split | 2.5 to 12kW | Comms cupboards, branch sites, single or double rack rooms | Specify continuous duty and a winter kit. A branded comfort unit in a white box is not the same thing |
| Downflow or upflow DX CRAC | 15 to 165kW | Dedicated server rooms and data halls, raised floor or overhead | Needs condenser space, refrigerant pipe runs within limits, and floor loading checked |
| Chilled water CRAH | 20 to 250kW | Sites with an existing chilled water plant, larger facilities | You inherit the plant's availability. If the chiller goes down at 2am, so does the data hall |
| In-row cooling | 10 to 50kW per pod | High density pods, contained aisles, edge deployments | Only worth it with containment. Without it you are paying for close coupling you do not get |
| Rear door heat exchanger and liquid | 40kW and above per rack | AI and GPU racks, high performance compute | Water or coolant in the white space. Needs leak detection and a maintenance regime |
Small rooms
Wall and ceiling mounted units
The range most people arriving at this page actually need. Purpose built for small critical rooms, rack rooms, network and switch rooms, UPS and battery rooms, and comms hubs where continuous cooling is essential but floor space is not available.
| Unit | Configuration | Capacity |
|---|---|---|
| Uniflair wall mount | Wall mounted split, small room precision cooling | Small room range |
| Uniflair ceiling mounted split | Ceiling mounted split, where wall space is unavailable | Small room range |
| Uniflair monoblock | Self contained monoblock, no separate outdoor unit | Small room range |
| Vertiv Liebert SRC-G, SRC03GES | Wall mounted split, 220V single phase, rotary compressor | 3.0kW |
| Vertiv Liebert SRC-G, SRC07GES | Wall mounted split, 220V single phase, scroll compressor | 7.0kW |
| Vertiv Liebert SRC-G, SRC07GET | Wall mounted split, 380V three phase, scroll compressor | 7.0kW |
| Vertiv Liebert SRC-G, SRC11GET | Wall mounted split, 380V three phase, scroll compressor | 11.0kW |
The SRC-G range sustains outdoor ambient to 48 degrees Celsius, runs a sensible heat ratio above 0.9, uses EC fans with step-less speed modulation, and supports SNMP monitoring, auto-restart after a power failure and sequencing of up to eight units. Washable G4 filters and a self-diagnostic controller make servicing faster. Download the Liebert SRC-G brochure.
Larger rooms
Room-based CRAC systems
Centralised cooling for the whole room, suited to dedicated server rooms, raised floor environments and data halls.
| System | Configuration | Capacity |
|---|---|---|
| Uniflair IDAV direct expansion | Air cooled, downflow, EC fans, variable speed scroll compressors | 20 to 50kW |
| Uniflair IUAV direct expansion | Air cooled, upflow, EC fans, variable speed scroll compressors | 20 to 50kW |
| Uniflair IDAV large format DX | Air cooled, downflow, variable speed scroll compressors, EC fans | 50 to 150kW |
| Uniflair chilled water | Chilled water, upflow, EC fans | 20 to 170kW |
| Uniflair chilled water, large format | Chilled water, downflow, EC fans | 140 to 250kW |
| FXCV chilled water | Chilled water, frontal discharge, large format room cooling | 130 to 250kW |
| Uniflair indirect free cooling | Indirect free cooling, downflow, VSD scroll compressors | 50 to 140kW |
| Liebert HPD dry cooler | Outdoor heat rejection, paired with chilled water systems | Project specific |
| Vertiv Liebert PDX | Precision downflow CRAC, air or glycol cooled | 15 to 165kW |
| Vertiv Liebert CRV in-row | In-row, room integrated, high density rack cooling | 10 to 50kW |
For the highest density AI and GPU workloads we also supply direct-to-chip and immersion liquid cooling, covered on our AI and high density infrastructure page. View the full precision cooling range.
Commercial
Server room cooling cost guide
Indicative unit pricing by system size for early budgeting. Figures exclude installation, ductwork and electrical works, and are based on typical Australian market pricing.
| System size | Typical use case | Indicative unit cost |
|---|---|---|
| 2.5 to 5.5kW | Comms cupboards, small server rooms, enclosures | $8,000 to $15,000 |
| 20 to 50kW | Medium server rooms and comms rooms | $25,000 to $45,000 |
| 50 to 90kW | Larger server rooms and small data halls | $45,000 to $60,000 and above |
| 100kW and above | Data centres and enterprise environments | Site specific consultation |
Condenser location and pipe run length are the two variables that move a quote most. Request a site assessment for a real figure against your room.
Redundancy
What N plus onemeans in a small room
N plus one means the room still holds setpoint with any one unit out of service, whether it failed or you took it off for a filter change. In a comms room with a 12kW design load, that means two units each capable of 12kW, not two units of 6kW.
Lead and lag rotation. The units must alternate on a timer, typically weekly. A standby unit that has not run for eight months will not start when you need it, and that is the single most common way paper redundancy turns out not to exist.
Separate electrical supply. Two units on the same final subcircuit share a single point of failure. Run them from different circuits, and preferably different distribution boards, to AS/NZS 3000.
Server equipment can begin thermal throttling or shutting down within minutes of losing adequate cooling, and sustained overheating causes permanent damage. Single unit rooms are a legitimate choice for low criticality sites, but be honest about it in the risk register and pair it with temperature alarming that actually reaches somebody after hours.
The details that get skipped
Condensate, drainage and compliance
The most common cause of a server room water incident is not a burst pipe. It is a blocked condensate drain on the cooling unit above the rack.
| Item | What it involves |
|---|---|
| Condensate route and pump | Gravity drain wherever possible. Where a pump is unavoidable, fit one with a high level alarm wired into the building management system or the room alarm |
| Leak detection | Rope or spot detection under the unit and along the drain run. Cheap, and it is the difference between a mop and an insurance claim |
| Air handling hygiene | AS/NZS 3666 applies to the maintenance regime as well as the install, particularly drain pans and filter changes |
| Electrical work | AS/NZS 3000 by a licensed electrician, with a compliance certificate issued |
| Refrigerant work | By a technician holding a current ARCtick licence from the Australian Refrigeration Council. Non-negotiable and checked on handover |
| Commissioning records | Superheat and subcooling, airflow, setpoint verification, alarm test and lead-lag changeover test, documented. If it is not written down it did not happen, and you will need it at the first warranty claim |
Where we work
Server room coolingacross Australia
Brisbane and QLD
Brisbane CBD, Tingalpa, Port of Brisbane, Logan, Ipswich, Sunshine Coast, Gold Coast, North Queensland
Our HQ. Subtropical heat and humidity place extra demand on condenser sizing and drain design.
Sydney and NSW
Sydney CBD, Parramatta, Western Sydney, North Ryde, Macquarie Park, Newcastle, Wollongong
Including CBD tower comms rooms where condenser locations are restricted and base building approval is required.
Melbourne and VIC
Melbourne CBD, Port Melbourne, Dandenong, West Footscray, Tullamarine, Geelong, Bendigo, regional Victoria
Winter operation matters here, so low ambient kits are specified as standard rather than as an option.
Perth, WA and Adelaide, SA
Perth CBD, Fremantle, Mandurah, Adelaide CBD, Port Adelaide, Whyalla, regional WA and SA
Extended heatwave design conditions mean we size condensers to peak ambient, not annual average.
Canberra and ACT
Canberra CBD, Civic, Fyshwick, Mitchell, Barton, Tuggeranong, Belconnen, Gungahlin, Queanbeyan
Federal departments, defence and agency data centres, aligned with Commonwealth procurement requirements.
Darwin, NT and the Pacific
Darwin, Palmerston, Alice Springs, Papua New Guinea, Fiji, Solomon Islands, Vanuatu
Some of the most demanding conditions in the region, where condensate volume and drain capacity are design items rather than afterthoughts.
Questions
Server roomcooling FAQs
The questions we are asked most before a site assessment. If yours is not here, call 1800 046 344.
Do server rooms need air conditioning?
Yes. Any room with a continuous IT load above roughly 1.5kW needs dedicated cooling, because that heat has nowhere to go and building air conditioning is typically off overnight and on weekends, which is exactly when nobody is there to notice the temperature climbing. Below 1.5kW you may get away with ventilation to an adjacent conditioned space, but only if that space is itself conditioned around the clock.
What air conditioner do I need for a small server room?
For a comms cupboard or a one to two rack room carrying 1.5 to 7kW, a wall-mounted or ceiling-mounted precision split rated for continuous duty is the right answer, typically in the 3 to 7kW band. Unit cost usually falls between $8,000 and $15,000 before installation. The critical specification points are continuous 24/7 duty rating, a sensible heat ratio above 0.9, and low ambient kit so it still runs through winter. A domestic split system in a white box is not the same product.
How do you size air conditioning for a server room?
Size on heat load in kilowatts, not floor area. Take the measured IT load from the UPS output, add UPS losses, lighting and 10 to 20 per cent for the building envelope, add roughly 0.1kW per person, then add 20 to 25 per cent growth headroom. If you want N plus one redundancy, each unit must be capable of that total on its own. Never size from equipment nameplate ratings, which typically overstate actual draw by 40 to 60 per cent.
How much does server room air conditioning cost in Australia?
Unit costs typically start from around $8,000 to $15,000 for a small wall-mounted or specialised unit at 2.5 to 5.5kW, rising to $25,000 to $45,000 for a room-based CRAC in the 20 to 50kW range, $45,000 to $60,000 and above for 50 to 90kW, and into six figures for larger systems above 100kW. Installation, commissioning and ongoing maintenance are additional. Condenser location and pipe run length are the two variables that move a quote most.
How hot is too hot for a server room?
ASHRAE TC 9.9 recommends 18 to 27 degrees Celsius measured at the rack inlet, with an allowable range of 15 to 32 degrees for Class A1 equipment. Above 32 degrees at the inlet you are outside the allowable envelope, thermal throttling and error rates rise, and warranty positions can be affected. Sustained operation above 35 degrees risks hardware shutdown and shortens component life. Note that these are inlet temperatures, not room temperatures.
Do I need a CRAC unit or can I use a normal air conditioner?
A comfort split delivers only 65 to 75 per cent of its nameplate as useful sensible cooling, is not rated for continuous 24/7 operation, over-dehumidifies a room with no moisture load, and usually will not run below about 15 degrees Celsius outdoor ambient. Typical life in this application is three to five years against twelve to fifteen for a precision unit, so the cheaper unit is rarely cheaper across the asset life.
Do I need two air conditioning units in a comms room?
If the room carries production workload, yes. N plus one means either unit alone can hold setpoint, so both must be sized for the full design load rather than half each. They should alternate on a weekly lead and lag rotation and run from separate electrical circuits to AS/NZS 3000. A single unit room is a valid choice for low criticality sites provided it is recorded as an accepted risk and backed by temperature alarming that reaches somebody after hours.
What is the difference between CRAC and in-row cooling?
A CRAC unit cools an entire room from a central point, typically along a wall or under a raised floor, and suits traditional server room layouts. In-row units sit directly between server racks, cooling the heat source at close range, which suits high density environments above roughly 10kW per rack where airflow management is more critical. In-row is only worth the premium if you also have aisle containment, otherwise you are paying for close coupling you do not actually get.
What is the $5,000 rule for air conditioning?
Multiply the age of the unit in years by the quoted repair cost. If the result is over $5,000, replacement is usually the better commercial decision. It is a rough guide built for domestic equipment, and for precision cooling you should also weigh refrigerant availability, spare parts support and the cost of the downtime a second failure would cause. We cover how it applies to data centre plant in our guide to the $5,000 rule for CRAC units.
Related services
Why us
Named products,published prices
We publish the ranges we actually supply and the cost bands we actually quote, so you can budget before you speak to anybody. Most of this industry will not do either.
Send us your measured IT load, the room dimensions and a photo of the existing unit, and we will come back with a heat load calculation and a scoped option with a real quote. If you do not know your measured load, tell us what is in the room and we will work it out at the site assessment.
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