Energiakulus

Energiakulus is a term used in energy accounting to describe the portion of input energy that is not converted into useful output within a system or process. It encompasses all forms of energy lost to inefficiencies, such as heat losses, friction, electrical resistance, transmission losses, and standby consumption. The concept helps assess how effectively a system uses energy and identifies opportunities for improvement.

Calculation is straightforward: if a device receives Ein of energy and delivers Eout as useful work or energy, the energiakulus is L = Ein − Eout. Efficiency is η = Eout / Ein, often expressed as a percentage. For time-based assessments, power losses can be described as the difference between input power and useful output power. Measurements require clearly defined system boundaries; what counts as useful output must be specified to avoid double counting.

Common examples include electric grids with line losses, heating, ventilation and air conditioning systems, engines with mechanical and parasitic losses, and electronics with standby power. In buildings, thermal energiakulus includes heat transfer through walls, windows, and air leaks.

Reducing energiakulus is central to improving energy efficiency and lowering operating costs and emissions. Approaches include improving materials and insulation, reducing parasitic power, optimizing processes, and upgrading to more efficient equipment. The term is related to but distinct from energiakulut, which more usually refers to the monetary cost of energy consumed.