When it comes to data center sustainability, you’ll often hear about PUE (power usage effectiveness). PUE has been originally developed by the Green Grid and is called “The Holy Grail” of data center metrics since then. PUE is the ratio of total amount of energy used by a computer data center facility to the energy delivered to computing equipment.
But PUE doesn’t tell the entire picture. That’s why there are other metrics (mostly developed by The Greend Grid) around that everyone in the data center business should know:
CUE (Carbon Usage Effectiveness): CUE is a metric for measuring the carbon gas a data center emits on a daily basis. This is calculated by dividing the total carbon dioxide emission equivalents (CO2eq) of the facility’s energy consumption by the total IT energy consumption. The output is measured in kilograms of carbon dioxide per kilowatt-hour. The perfect CUE score is 0.0, meaning that no carbon use is associated with the data center’s operations.
WUE (Water Usage Effectiveness): WUE helps data centers tomeasure how much water a facility uses for cooling and other building needs. To calculate this, a data center manager divides the annual site water usage in liters by the IT equipment energy usage in kilowatt hours (Kwh). Water usage includes water used for cooling, regulating humidity and producing electricity on-site.
DCeP (Data Center Energy Productivity): DCeP is a sophisticated metric that quantifies useful work compared to the energy it requires. It can be calculated for an individual IT device or a cluster of computing equipment. Basically a calculation will look like this: DCeP = Useful work produced / Total data center energy consumed over time.
RUE (Rack Use Effectiveness): This newly proposed metric by David Cappuccio, who is responsible for data center research at Gartner, is based on the same optimal/actual usage concept behind the PUE, but the RUE would measure how much of the available rack space is being used.