Hot & Cold Aisle Containment

Separating the hot from the cold aisles prevents cold air short-circuiting straight back to the air conditioning system before it has done any useful work. This offers one of the easiest ways of reducing cooling energy costs and can be incorporated into new designs or retro-fitted in existing data centres.

It has the benefits of:

• Preventing mixing of cold supply air with hot return air thus immediately improving energy efficiency
• Allowing increased return temperatures which will further reduce cooling energy use
• Reducing air volumes thus saving on fan energy
• Eliminating ‘hot-spots’

Either the hot or the cold aisle can be contained and which one is best will vary from one data centre to another. Hot aisle containment has the advantage that the room as whole is at a comfortable temperature while cold aisle containment is easier to retro-fit.

In principle there is no difference between the two systems in their potential for saving energy, although in practice a contained hot aisle can be run hotter than a contained cold aisle which would improve its performance.

In existing data centres the type of air handling plant and the air distribution system will be deciding factors as to which solution is adopted. For example, APC in-row cooling is ideal for an enclosed hot aisle whilst an under-floor supply with room return to CRAC units would be better suited to cold aisle containment.