Functional unit

The functional unit defines what is being studied and provides a reference to which all data is normalized. It's a quantified description of the performance of a product system for use as a reference unit, it’s defining the service the product provides.The unit that all inputs, outputs and the results in the study are related to. Examples of functional units include

• Lighting: "Providing 1000 lumens of light for 10,000 hours at a specified color temperature."
• Transportation: "Transporting one person over one kilometer."
• Cleaning: "Cleaning 100 square meters of floor to a specified level of cleanliness over one year."
• Beverage Container: "Containing and delivering 1 liter of beverage with a shelf life of 7 days."