Kill a Watt!

As a followup to my Friday post, here are a few more details of our "kill-a-watt" project. This is a multi-year effort by the staff to "green-up" the data center and IT electrical footprint that extends to the medical center.

1. Eliminate old monitors - Conversion from cathode ray tube-based (CRT) to LCD flat panel computer monitors. The typical power consumption for a CRT is .41 kwh's per day. A year ago, we had 7,500 CRT's. Today, we have reduced the number to 2,400 having replaced the others with 15" or 17" LCD flat panel monitors. The latter consume an average of .29 kwh's per day (17") or .11 kwh's per day (15"). Based on the effort to date, we have lowered the annual electrical power consumption for computer monitors from 1,122,375 kwh's per year to approximately 459,189 kwh's per year. This includes the impact of 500 additional monitors that were new to the environment.

2. Server Consolidation - Many of our computer servers in the data center support only one application. This is often requested by the application vendor. Virtualization software such as VMWare is now available that allows multiple instances of a computer operating system to exist on the same server. Each instance can be configured in a way that assures needed server resources (memory, CPU, etc) are available. We have retired over 20 servers in the past year through this technique.

3. Computer Center Utilities - There have been several initiatives related to the data center. Prior to 2007, we were tracking to exceed 200KW's of peak power consumption in the data center by 2010 based on the growth of electrical demand. The latter was caused by new storage, servers and switches. We were also seeing a 1:1 ratio between the data center load (servers, storage, switches) and the mechanical systems required to cool the data center and light it. In other words, for every watt used in the data center, we needed another watt to cool the heat produced.

Our goal was to stay well below 200KW peak load in the data center and reduce the 1:1 ratio. While we are not done, we have essentially achieved our goal. Today, we run at about 160KW at peak load; below the 170KW~ peak loads we have seen in the prior year. This is despite the increased number of terabytes of storage and applications the medical center has demanded we support. This has come about by consolidating servers, replacing older, less energy efficient devices, and reconfiguring equipment.

The data center load to mechanical (HVAC) load has also improved. Instead of 1:1, we are now running at about 1 watt of data center use for every .7 watt of mechanical load. This has been the result of better thermal management (e.g. reducing underfloor cables, using perforated inserts, shutting down an unneeded A/C unit, adjusting humidistats to increase efficiency, using blanking panels and other methods to better direct air-flow (i.e. hot aisle/cold aisle enforcement), and other techniques.