In a Life Cycle Analysis, the impact associated with 1 Functional Unit is calculated. It is a quantitative and qualitative sentence that describes what your Solution and the Mainstream alternative aim to fulfill. For example, the Functional Unit of a lamp bulb can be to light a 50 square meters class room for 8 hours a day for 10 years. Both the Solution and the Mainstream Alternative can fulfill this FU, but the environmental impact associated with each option is different.
The Functional Unit is the reference of the quantities that will be used in the SEI tool in each of the life cycles. For example, let’s assume the technology we want to assess is a Diesel Generator and the FU is to produce 1 kWh of electrical energy in all conditions and at any time. If the manufacturing of 1 unit of the diesel generator requires 70 kg of steel and this same unit produces 80 GWh (80 000 000 kWh) of electricity in its lifetime, then the emissions to take into account will be the emissions to produce 70 kg of steel divided by 80 000 000. This will give the equivalent manufacturing emissions for producing 1 kWh of electricity (so 1 FU) with the Diesel Generator.