4. Use free cooling: Free cooling is removing heat from your facility without using the chiller. This is done by using low temperature ambient air, evaporating water, or using a large thermal reservoir. Chillers are the dominant energy using component of the cooling infrastructure; minimizing their use is typically the largest opportunity for savings. There is no one right way to free cool, but water or air-side economizers are proven and readily available.
5. Optimize power distribution: Minimize power distribution losses by eliminating as many power conversion steps as possible. For the conversion steps you must have, be sure to specify efficient equipment transformers and power distribution units. One of the largest losses in data center power distribution is from the uninterruptible power supply; be sure to specify a high efficiency model. Also keep as high a voltage as close to the load as feasible to reduce line losses.
Read more about data center in Network World's Data Center section.