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Running Data Centers at Higher Voltages for Energy Savings
Data Center Electrical Distribution: 400/230 Volts vs. 120 Volts
Running IT equipment in data centers on 400/230 volts AC, as is common practice outside of North America, will reduce resistance and conversion losses.
Synopsis:
Data centers use a significant and increasing portion of the total electricity consumed in the U.S. and globally. Electricity is lost:
- In the distribution of electricity through resistance losses.
- During each step required to change voltages and transition from alternating current (AC) to direct current (DC) through power distribution units or uninterruptable power supplies.
- When removing heat generated from these activities.
Modifying data centers to operate at higher voltages to reduce current losses could significantly increase the energy efficiency of these facilities. But is high-voltage AC or DC a superior option for energy savings? Lawrence Berkeley National Laboratory (LBNL) tested 380V DC against conventional high-efficiency, low-voltage (208 V AC) systems (Tschudi 2007). Schneider Electric suggested that high-voltage AC (400/230 V AC) is a superior option and points out that the LBNL study is no longer accurate due to advances in AC uninterruptable power supply (UPS) efficiency (Rasmussen and Spitaels 2012).
High-voltage DC and high-voltage AC options, with modern high-efficiency equipment, represent significant efficiency gains over standard data center designs. Schneider Electric suggests that high-voltage AC is the most efficient of these options and would be compatible with existing equipment. They note that high-voltage (400V) AC distribution to data centers is standard practice everywhere in the world outside of North America and go on to suggest that this practice be adopted in the U.S. moving forward.
Energy Savings: 5%
Energy Savings Rating: Extensive Assessment
What's this?
| Level | Status | Description |
| 1 | Concept not validated | Claims of energy savings may not be credible due to lack of documentation or validation by unbiased experts. |
| 2 | Concept validated: | An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles. |
| 3 | Limited assessment | An unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline. |
| 4 | Extensive assessment | Additional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions. |
| 5 | Comprehensive analysis | Results of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications. |
| 6 | Approved measure | Protocols for technology application are established and approved. |
Simple Payback, New Construction (years): -11.4
What's this?
Simple Payback is one tool used to estimate the cost-effectiveness of a proposed investment, such as the investment in an energy efficient technology. Simple payback indicates how many years it will take for the initial investment to "pay itself back." The basic formula for calculating a simple payback is:
Simple Payback = Incremental First Cost / Annual Savings
The Incremental Cost is determined by subtracting the Baseline First Cost from the Measure First Cost.
For New Construction, the Baseline First Cost is the cost to purchase the standard practice technology. The Measure First Cost is the cost of the alternative, more energy efficienct technology. Installation costs are not included, as it is assumed that installation costs are approximately the same for the Baseline and the Emerging Technology.
For Retrofit scenarios, the Baseline First Cost is $0, since the baseline scenario is to leave the existing equipment in place. The Emerging Technology First Cost is the Measure First Cost plus Installation Cost (the cost of the replacement technology, plus the labor cost to install it). Retrofit scenarios generally have a higher First Cost and longer Simple Paybacks than New Construction scenarios.
Simple Paybacks are called "simple" because they do not include details such as the time value of money or inflation, and often do not include operations and maintenance (O&M) costs or end-of-life disposal costs. However, they can still provide a powerful tool for a quick assessment of a proposed measure. These paybacks are rough estimates based upon best available data, and should be treated with caution. For major financial decisions, it is suggested that a full Lifecycle Cost Analysis be performed which includes the unique details of your situation.
The energy savings estimates are based upon an electric rate of $.09/kWh, and are calculated by comparing the range of estimated energy savings to the baseline energy use. For most technologies, this results in "Typical," "Fast" and "Slow" payback estimates, corresponding with the "Typical," "High" and "Low" estimates of energy savings, respectively.