Understanding how to cool small server rooms is becoming more and more important. More SME’s are choosing to host their own on-site hardware rather than using cloud based services. In a lot of cases the equipment starts off small and is allocated a small room or space on the office floor . However just like the company, the equipment starts to grow.
Equipment overheating in small rooms could lead to downtime. This is why it’s essential that both IT and facility managers understand the importance of cooling small server rooms.
What’s different about these rooms?
Firstly compared to normal comfort cooling, the heat load density, i.e kW of heat gain per m2 floor area, is much greater (typically 3-5 times greater). Secondly, the heat load is 100% ‘sensible’ as opposed to comfort cooling which is typically 70/30% sensible/latent. Additionally, the requirement for cooling 24 hours a day compared to just normal working hours for comfort cooling.
What’s the difference between sensible and latent heat load?
Sensible heat gain is heat that raises the room temperature, whereas latent heat raises the room moisture content (for example from moisture ingress through fresh air, or human perspiration).
The sum of sensible + latent = The total heat gain
What equipment should I select?
There are manufacturers that specialise in equipment with high “Sensible Heat Ratio” or more commonly known as “close control” equipment. This equipment is specifically designed to keep unnecessary (wasteful) latent cooling to a minimum. This type of equipment also has a higher filtration standard, plus the option of relative humidity control, both of which are useful for server room equipment.
Isn’t close control equipment much more expensive?
The upfront costs are typically more expensive which is why you see a lot of small server rooms using comfort cooling equipment. However when you look at the total life cost, close control equipment probably works out more economical as it typically lasts 2-3 times longer than comfort cooling.
But isn’t comfort cooling more energy efficient with inverter drives?
Yes, when you look at power input compared to output. But the output is total, not sensible, so you’re effectively wasting the latent content (30%) of the output.
Also, for server rooms, the inverter driven aspect should not be a factor when correctly sizing the equipment because the load is reasonably constant, as opposed to variations in comfort cooling demand.
A correctly sized system, rather than an oversized one, will be the most efficient solution.
What’s the best solution for my server room?
The correct solution depends on heat gain, criticality, size of room, back-up requirement, speed of maintenance response and, of course, your budget.