Energiamérleg

Energiamérleg is the Hungarian term for energy balance, a concept used to describe the accounting of energy flowing into and out of a system. It is grounded in the first law of thermodynamics, which states that energy cannot be created or destroyed, only transformed. An energiamérleg tallies all energy inputs and all energy outputs to determine how the system’s stored energy changes over time.

In practical terms, energy input minus energy output equals the change in stored energy. In a steady state, the stored energy remains constant, so the energy input equals the energy output. This framework applies across disciplines, from physics and engineering to biology and ecology, by identifying the relevant inputs, outputs, and storage terms for the system being studied.

In human nutrition, energiamérleg refers to the balance between energy intake from food and beverages and energy expenditure from metabolic processes, physical activity, and digestion. A positive energy balance tends to promote weight gain, while a negative balance tends to promote weight loss. Energy intake is commonly expressed in kilocalories or kilojoules, and expenditure includes basal metabolic rate, the thermic effect of food, and activity energy.

Other applications include building and industrial energy management, where the goal is to minimize losses and maximize efficiency, and ecological accounting, where energy inputs (e.g., sunlight and photosynthesis) are weighed against losses (respiration, heat) to understand ecosystem productivity.

Measurement of energiamérleg relies on estimates and measurements of inputs, outputs, and storage changes, and may involve dietary records, metabolic rate assessments, energy auditing, and modeling. Limitations include measurement error and variability in individual energy use.