The Green Grid: Guidelines for Energy Efficient Data Centers
The Green Grid's whitepaper shows that only 30% of data center energy consumption is actually for value-adding IT equipment, while the remainder is for facilities and infrastructure.
The Green Grid is a consortium of eleven major IT companies, including AMD, APC, Dell, HP, IBM, Intel, Microsoft, Rackable Systems, SprayCool, Sun, and VMware (via Sustainable IT). They have published three whitepapers on environmental data center topics. One of those is Guidelines for Energy Efficient Data Centers (pdf).
After starting to read the whitepaper, I think they are missing their biggest energy saving opportunity by trying to solve the efficiency problem backwards.
In one section of the white paper, they talk about "system design issues that commonly reduce the efficiency of datacenters" including:
- Power distribution units and/or transformers operating well below their full load capacities.
- Air conditioners forced to consume extra power to drive air at high pressures over long distances.
- Cooling pumps which have their flow rate automatically adjusted by valves (which dramatically reduces the pump efficiency).
- N+1 or 2N redundant designs, which result in underutilization of components.
- The tradition of oversizing a UPS to avoid operating near its capacity limit.
- The decreased efficiency of UPS equipment when run at low loads.
- Under-floor blockages that contribute to inefficiency by forcing cooling devices to work harder to accommodate existing load heat removal requirements. (This can lead to temperature differences and high-heat load areas might receive inadequate cooling)."
While these are important system design issues, they miss one critical factor: for each one watt consumed by directly by IT equipment, 2.3 watts are consumed by infrastructure that doesn't add customer value. Now where should we focus our resources on energy efficiency? If we save 1 watt in non-value adding infrastructure, we've saved 1 watt in total. if we save a watt in the power consumed by IT equipment, we save not only that 1 watt, but another 2.3 watts in infrastructure that isn't needed, for a total of 3.3 watts saved. Therefore, the biggest leverage for our time, effort, and money is in focusing directly on the IT equipment. The data center infrastructure should come only after we've wrung every efficiency we can out of the IT equipment.
As we increase the efficiency of the underlying IT equipment, we would at first see a decreasing return on investment. But when we push the limits on efficiency, we can achieve what Amory Lovins of the Rocky Mountain Institute calls "tunneling through the cost barrier". For example, if efficiency increases radically, we reduce our cooling need dramatically, and can eliminate fans or air conditioning units, leading to a secondary decrease in energy consumption.
Amory Lovins and Paul Hawkin cowrote "Natural Capitalism", which has a chapter available online (pdf) on this very topic.