Today I’ve been reading IBM data center gets deep energy retrofit. In this post, I’m going to talk about the cooling techniques described here and the hot aisle/cold aisle technique in general.
One of the “green” cooling techniques commonly touted is hot aisle/cold aisle. In this technique, cold air is introduced at the front side of the cabinet, hot air is exhausted from the back side of the cabinet, and rows alternate back to back and front to front. This allows the hot aisle to be separated from the cold.
The IBM cooling mentioned in the article adds water cooling coils at the back door of the cabinet to cool the exhaust air directly.
Both these methods are certainly better than simply dumping air out the back of the cabinets, however, I consider them far from being green.
In both cases, energy has to be applied to move air against its natural tendency. Additionally, dumping the hot exhaust air out of the cabinet and then having to corral it again in the hot aisle containment is hardly efficient.
Finally, consider the energy required by the extensive active cooling of the IBM system and it becomes a very odd shade of green.
So, what are the keys to green cooling? Make use of the natural cooling of ambient air, keep as fine a control of airflow as possible, and take advantage of the natural air movement of the air to use as little energy moving it as possible.
So, how do we accomplish this?
1. “Chimney” airflow cabinets with the exhaust directly vented into a plenum.
2. All air handling above the cabinets (cold air falls to the cabinet intakes, hot air naturally rises through the exhaust plenum). Just another reason to skip the raised floor!
3. Free air cooling.
You have to put the energy into the air in the form of waste heat, let that energy make the air work for you!
Vern, SwiftWater Telecom
Data center, web hosting, Internet engineering