Free cooling for data centres

Data CentreThere’s no arguing with the fact that data centres and server rooms use a lot of energy. And one of the biggest contributors to the energy bill is the cost of data centre cooling, especially when using conventional chiller units. Cooling server rooms consume a staggering 1% of the world’s energy. It’s not surprising then that data centre operators are increasingly interested in the concept of free cooling or the use of fresh air.

In most data centres and server rooms the air-conditioning runs continuously, even when it’s cold outside. And in the UK, it’s sufficiently ‘cold outside’ to not need server room air conditioning for almost nine months of the year, because the ambient temperature remains below 15°C.

It’s a pretty obvious solution: when it’s cold outside, just bring the fresh air inside to cool the server room. It is still possible to filter the air and control the humidity but the free-cooling approach uses a lot less power than running standard air conditioning chiller units. And because today’s computer equipment is a lot less sensitive to slight variations in temperature and humidity than it used to be, fresh-air cooling is an increasingly attractive solution for many data centre operators.

Evaporative cooling

What we have described above, in a nutshell, is ‘free cooling’, and what could be better than just ducting in and filtering the fresh air from outside and using it to cool the servers?

The answer is adiabatic, or evaporative cooling. This approach enables server rooms to use outside air even when the ambient temperature is above the temperature required to provide effective free cooling. For example, using evaporative cooling can reduce an ambient temperature of 30°C to 22°C when the relative humidity is 35%, at a fraction of the cost of powering conventional chiller units.

Both free cooling and adiabatic (or evaporative) cooling equipment can be installed in new-build data centres as well as being retrofitted to existing data centres. The main requirement is that there is the means to fit ducting to enable the outside air to be brought in to the server room.

Evaporative cooling is just one of the power reduction solutions for data centres and server rooms that is available from UPS Systems. We look at the complete infrastructure energy demands of the server room, and propose energy-efficient solutions for uninterruptible power supplies and other critical systems.