Allocate energy to measured lost air
Annual equivalent energy = leak flow in m³/min × specific electrical input in kW/(m³/min FAD) × hours per year. Multiplying by £/kWh gives the indicative allocated annual cost. The leak flow and specific-power delivery figure must use the same pressure and free-air reference basis.
To obtain specific electrical input power, divide electrical input by FAD measured together at full load and normal working pressure. For example, 30 electrical kW ÷ 5 m³/min FAD = 6 kW/(m³/min FAD). Do not substitute motor nameplate power or guess an efficiency. Use hours when the system is pressurised, even outside production hours. Use a competent survey for unknown leakage; this tool does not estimate leak flow from hole size.
Worked example: £6,000 allocated per year
A measured 1 m³/min leak at 6 kW/(m³/min FAD) represents 6 kW of equivalent input. Across 4,000 hours that is 24,000 kWh. At £0.25/kWh the indicative allocated cost is £6,000 per year.
Cost is not a guaranteed saving
Repairing a leak does not necessarily reduce electrical input by this amount. Compressor controls, unloaded power and how the plant responds affect the actual saving. Confirm the change using electrical measurements and comparable operating conditions. Zero leakage, zero hours or a zero tariff legitimately produces a zero annual cost.