Data centers are used to house and run IT operations worldwide. These facilities are typically large and require a lot of energy, and with sustainability concerns on the rise, data centers have been in the spotlight regarding their environmental impacts.
As more and more businesses move to off-site IT sources, the need for sustainable data centers is essential for sustainability. Data centers use three efficiency metrics to measure sustainability — power usage effectiveness (PUE), carbon usage effectiveness (CUE) and water usage effectiveness (WUE).
Learn more about these sustainability metrics and how data centers can use them to reduce environmental impact.
Power Usage Effectiveness
PUE is one of the most common efficiency metrics for data centers to measure. Data center PUE is the ratio of total data center energy use to IT equipment energy use. Total energy use refers to all of the facility's loads, including everything from the IT equipment to lighting and cooling systems. IT energy use refers to everything strictly related to IT computing, storage and networking equipment and the associated controls.
To calculate a facility's PUE, you would divide the total energy usage by the IT equipment energy usage. PUE is typically calculated over time to determine a facility's overall performance vs. its baseline. When taking readings for the total calculation, take readings at the facility utility meter. If the data center is part of a larger facility, only take readings for the area dedicated to the data center. Then, measure the IT load with all power conversions, switching and conditioning on.
Comparing PUE across multiple data centers is difficult because several factors can affect it, and each facility may use different configurations. Much of these differences depend on how a facility consumes its energy. For example, energy consumption can vary depending on factors like:
Climate and weather
Power grid services
Building materials and layout
PUE plays a significant role in data center sustainability because it provides facilities with important efficiency insights. Measuring PUE helps data centers achieve energy efficiency and operational cost savings.
Carbon Usage Effectiveness
CUE is a metric used to measure sustainability regarding data center carbon emissions. The metric is the ratio of total data center carbon dioxide (CO2) emissions to IT equipment energy consumption. You can calculate data center CUE by dividing the CO2 emissions from total energy use by IT equipment energy use.
For the equation, carbon emissions can be based on local government data if the facility's electricity comes from the grid. If electricity is produced on-site, the readings can come from local meters. Where the energy comes from can affect how much a facility uses.
CUE helps data centers understand how much of their total CO2 emissions are attributed to the energy IT equipment uses. With these insights, data centers can take action to reduce their environmental impact. Carbon emissions are also heavily regulated by various organizations, meaning data centers must comply with regulations regarding the production and handling of emissions. Measuring and tracking CUE helps facilities maintain compliance.
Water Usage Effectiveness
Data centers use water for cooling systems and generating energy. These facilities have a high demand for water, which isn't necessarily abundant, as water consumption continues to rise. As such, data center WUE measures the amount of water used to cool IT assets. Calculating a facility's WUE is the ratio of water used at the data center to the electricity delivered to IT hardware.
Several factors affect a facility's WUE, including:
Climate: Cooling is one of the primary uses of water in a data center. Depending on the climate where a facility is located, it may have a higher or lower need for cooling.
Type of cooling system: The cooling system in the facility affects the WUE. Water cooling systems require a facility to use significantly more water than they would with a waterless cooling system. Waterless cooling systems can help data centers cut back on water usage.
Power sources: Whether a facility generates power with water will also affect WUE. Depending on the power source used, water consumption varies.
WUE plays a significant role in data center sustainability, helping facilities conserve water and optimize water management. On average, data centers consume several million gallons of water per day, which isn't sustainable over the long term. WUE allows data centers to quantify their water usage and determine where water consumption can be reduced.
In order to lower water usage, data centers should switch to or be designed with waterless cooling systems or look for ways to use water more efficiently, like recycling water.
The Synergy of PUE, CUE and WUE in Sustainable Data Centers
These three metrics are considered the triad of data center sustainability. Monitoring all three metrics gives facilities the most comprehensive view of their operations' efficiency, which helps in identifying operational progress. Improvement opportunities create the potential for cost savings, increased efficiency and overall sustainability.
While these metrics should be used in conjunction, they don't necessarily consider each other in efficiency calculations. For example, using a water-based cooling system powered by electricity can improve PUE and worsen WUE. However, both metrics should be considered together to optimize efficiency. In this sense, facilities must balance trade-offs among the three metrics to achieve optimal sustainability.
Together, PUE, CUE and WUE can impact data center sustainability in several ways, such as:
Environmental benefits: Reduced power usage, carbon emissions and water consumption significantly reduce data centers' environmental impact.
Cost savings: Data centers with sustainable business practices are eligible for government incentives and rebates, helping increase cost savings for the facility and its clients.
Enhanced reputation for businesses: Businesses that partner with sustainable data centers gain a reputation for being eco-conscious, which bodes well with the majority of consumers.
Partner With US Signal for Sustainable Data Centers
At US Signal, we're committed to operating our data centers in the most sustainable way possible. We're on the road to powering all our data centers with renewable energy, helping us reduce our carbon footprint and yours. Our green data centers are helping reduce our environmental impact while meeting your IT needs and getting you closer to your sustainability goals.