The design of the modern day server and rack mount equipment means air is pulled through the server from front and exhausted at the rear of the server cooling down the critical server components, therefore it is vital that the air at the front of the racks is at an optimum temperature and humidity.
Without cold aisle containment the air-conditioned air mixed with other warmer air from hot aisles and the rest of the room, the result is that the ambient temperature in the cold aisle increases, leading to less effective cooling. Cold aisle containment ensures the air entering the cold aisle is kept segregated from the other warmer air as much as possible.
The key to cold aisle containment is to minimise cold air leakage from the aisle. Above each rack plastic sheeting has been installed to prevent air escaping, and at the entrance to a cold aisle we have installed a PVC Curtain, this allows access to the cold aisle but minimises air loss. Within each rack unused space has been blanked off. The maximises air flow through the equipment installed within the racks. The cold aisle is also kept at a positive pressure to the datacentre room by ensuring slightly more air enters the cold aisle than leaves through the equipment in the racks, assisting with air-flow.
Previously our Air Handling Units recirculated the air within the datacentre, temporary duct work has been installed to the units to circulate fresh outdoor air effectively providing totally free cooling when the outdoor temperature is low.
The results so far over the past few weeks have shown a 60% increase in the efficiency of our HVAC system. This is probably helped by our fairly poor summer weather at the moment.
We've had a few issues along the way, mainly with rack-mount equipment incorrectly mounted in reverse (more specifically switches installed at the rear of racks), but these have been overcome and more work will continue in the coming weeks with installation of permanent ducting.