Energy Efficiency Metrics for a Green Data Center Facility

Dec 20, 2022 | DCIM

The Energy Efficiency metrics for a Green Data Center Facility provide a way to measure and assess the efficiency of a data center. By using the metrics, a data center can better understand where it is excelling and where there are areas for improvement. The ultimate goal is to have a green data center that operates efficiently and at a low cost while being environmentally responsible.

Why are Data Center Energy Efficiency Metrics Important?

Energy efficiency plays an essential role in the operation of a data center, as they are one of the world’s largest energy consumers. The demand for electricity from data centers is expected to double by 2050. Data centers are responsible for 2% of global CO2 emissions, likely to rise with increased use. In addition to environmental impacts, data centers also have economic implications; if data centers fail due to a lack of electricity, businesses sustain losses in revenue through downtime.

Not every efficiency metric may apply to every facility. When optimizing energy usage in a data center environment, it’s good to know what information you need to track down so you can make informed decisions about your energy usage.

Every data center has its unique infrastructure, which makes it challenging to identify potential problem areas. There are also many ways that you can use data center metrics to improve your enterprise’s environmental impact. By reviewing your current data centers’ performance and applying the right metrics, you can make informed decisions about eliminating wasteful practices and improving your environmental performance.

Data center managers should therefore adopt a holistic approach to managing their data centers by applying operational best practices and implementing proven strategies. This strategy will help them achieve competitive advantages in energy efficiency, reduced operating costs, and environmental footprint while assisting them in managing their data center assets better and optimizing their return on investment (ROI).

Data Center Energy Efficiency Metrics

The Uptime Institute has recently developed a new Energy Efficiency Score (EES) to help data center managers quantify the energy efficiency of their server room facilities. This metric was designed to meet the rising demand from clients for greater transparency into their energy usage and costs, as well as the need for a universal methodology for assessing different types of data centers and allowing for comparisons across similar facilities.

The EES consists of two sub-scores: Energy Performance Index (EPI), which rates the consumption level for each building, and Power Usage Effectiveness (PUE), which measures how effectively energy is utilized inside the facility by comparing computer equipment power to the entire building’s power. A PUE score of 1 means that the computers are consuming all available energy, while a score of 2 means that half of the building’s power is going toward supporting equipment in the facility—a sign that improvements need to be made.

While it would be boring to list every metric an organization could use to measure their facility’s energy efficiency, we’ve compiled an extensive list of metrics that should help organizations determine how well they’re keeping their data centers green.

Here are some data center energy efficiency metrics that help us to understand which side needs to be optimized.

Data Center Infrastructure Efficiency (DCIE)

Data Center Infrastructure Efficiency (DCIE) measures the efficiency of data center infrastructure. It is calculated by dividing the total cost of resources consumed by a data center by the total IT load in kilowatts (kW).

DCIE = (Total IT Equipment Power)/(Total Facility Energy Consumed)

For example, if a data center has an IT load of 1000 kW and consumes $1.5M in resources, its DCIE will be 1.5M/1000 kW = 0.015 or 1.5%. The higher the DCIE, the better the infrastructure efficiency.

Power Usage Effectiveness (PUE)

Power Usage Effectiveness (PUE) measures how efficiently a data center uses energy. It is calculated by taking the total amount of power used by the facility and dividing it by the number of racks. When PUE is low, more of the facility’s power is used for computing functions instead of cooling and other overhead costs. The most effective data centers have PUEs below 1.25.

Data Center Efficiency Ratio (DER)

Data Center Efficiency Ratio (DER) is an important metric that helps measure a data center’s energy efficiency.

The DER formula is:

DER = Data Center Energy Usage / IT Equipment Energy Usage

Read also: Improving Data Center Energy Efficiency with This 8 Things 

Server Load Effectiveness (SLE)

Server Load Effectiveness (SLE) is a metric that illustrates how effectively a server distributes the load. SLE is calculated by dividing the amount of work done by a system by the time it takes to process that work and subtracting one from the result. It shows how many work units are handled per second.

A higher SLE value means a system is more efficient in handling load. A lower SLE implies that a system needs more time to complete the same work.

SLE calculation: WU/T = SLE

  • WU: Work Units
  • T: Time is taken for the workload to execute

For example, if a server’s SLE is 92%, it means that, on average, it can process 92% of its tasks during peak load periods.

Energy Efficiency of a Data Center System (EECS)

The EECS of a data center system is an indicator of the energy efficiency of the data center system. The Energy Efficiency Ratio (EER) of a data center system is a common metric to measure the energy efficiency of a data center. It is often calculated by dividing the annual electricity consumption of the data center by its annual IT equipment power consumption.

The energy efficiency ratio (EER) indicates the relative thermal performance of a cooling device. Higher EERs are better because they indicate that more heat is being removed for each unit of energy input (i.e., greater thermal performance). For example, if two devices have an EER of 3 and 6, the first device is twice more efficient at removing heat than the second.

A more general term may be the Energy-Performance Ratio (EPR), which includes factors such as cooling energy, floor space, and environmental impacts in addition to electrical energy for IT equipment power consumption.

The first step to improving either EER or EPR is to monitor the actual hardware and software components contributing to the overall energy consumption. For example, an HVAC system might run at total capacity even if the temperature inside the room is comfortable enough for users, resulting in wasted energy. The next step would be to investigate whether there are any ways to improve the efficiency of these components. For example, if there is excess capacity for cooling in the HVAC system, it could be used more efficiently by introducing more airflow through the room. The third step would be to determine whether there are any additional opportunities for improvement – perhaps some equipment could be replaced with newer and more efficient models.

Energy Reuse Factor (ERF)

The Energy Reuse Factor (ERF) is a metric that indicates the percentage of energy reused by the data center after subtracting all the energy consumed by IT equipment, supporting infrastructure, and systems. It represents an efficiency number between 0 and 100.

ERF must be computed as a ratio of total energy consumption divided by reuse energy. ERF is used to compare the efficiency of data centers in terms of how much power is being reused for other purposes.

“Reuse energy” refers to the amount of power injected into the power distribution network from an on-site generator. “Recovered energy” represents the difference between purchased/delivered power and total consumption.

ERF = (reuse energy) / (total energy consumed)

The concept of ERF can be illustrated with an example. Assume that a 1 MW data center has a peak demand of 1200 kW and purchases 1,200,000 kWh of electricity per month at $150,000. The ERF would be 5% (120,000 kWh / 1,200,000 kWh). In other words, 5% of the total power required by the facility was generated on-site and reused in place of purchased/delivered power.


The world of data centers is constantly changing. Data centers need to evolve as the applications they serve to do, and they are only as efficient as their user’s demand. One of the most significant changes in recent years has been heightened concerns about how much energy data centers use, particularly from a financial perspective. As a result, there has been a growing trend toward developing methods for data center companies to measure their energy usage and identify ways to reduce it.

Because green data centers are built with sustainable design features, they can achieve high-performance levels and superior reliability without compromising on the environment. They can also help cut down on long-term maintenance costs due to using energy-efficient components that do not break down easily or rust over time.

A strategic commitment to operating more efficiently can significantly affect your bottom line. A data center could reduce energy costs and carbon emissions using energy efficiency metrics.

Those metrics are valuable tools that can be used to evaluate and improve a data center’s efficiency. Using this tool and tracking the metrics makes it possible to measure how close a company achieves its goal of running an efficient and environmentally friendly facility.

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