How is SEC per liter of milk calculated?

Add the plant's electrical and thermal energy for a period, converted to a common unit, then divide by the liters of milk processed in that period.

Why does SEC rise when volume falls?

Refrigeration, compressed air, lighting and other base loads keep running regardless of volume. With fewer liters to share them, energy per liter goes up.

Is SEC the same as an EnPI?

SEC is a common energy performance indicator, or EnPI, under ISO 50001. A good EnPI adjusts for the variables that drive energy use, such as throughput and weather.

Can SEC be compared between dairies?

Only with care. Product mix, processes and climate differ. Comparing a plant against its own normalized baseline is usually more reliable.

Glossary

Dairy and food processing

What is Specific energy consumption (SEC) per liter of milk?

Definition

Specific energy consumption (SEC) per liter of milk is the total energy a dairy uses to receive, process and store milk, divided by the liters processed. It turns a monthly energy bill into a comparable efficiency figure, so plants of different sizes, or the same plant across seasons, can be compared fairly.

What it is

SEC divides energy use by production output. In a dairy, the output is usually liters of milk handled or processed, and the energy is electricity plus thermal energy from steam, hot water or fuel, converted to a common unit.

A single plant-level SEC is a starting point. A more useful version breaks SEC down by process area, such as reception, pasteurization, refrigeration, CIP, powder or product lines, because each area responds to different drivers.

SEC changes with product mix, throughput and weather. Low volume days often show higher SEC because base loads such as refrigeration and compressed air keep running. Fair comparison needs these factors in the baseline.

Who it applies to / where it is used

SEC is used by dairy cooperatives and processors, energy managers, auditors and, in some countries, regulators. In India, specific energy consumption is the core metric in Bureau of Energy Efficiency programs for designated consumers in several industrial sectors.

How it is measured / what evidence it needs

SEC needs energy by source and production by the same period, ideally by line or process area.

Electricity by feeder and process area
Steam, fuel or hot water energy, converted to a common unit
Liters received and processed by period
Product mix and throughput
Ambient conditions for refrigeration-heavy areas

How Aqueduct helps

Aqueduct builds SEC from metered data, not monthly bills, so it can be tracked daily and by process area.

aQ EnergySmart calculates SEC by plant, line and process area
Regression baselines account for throughput and degree days
aQ WaterGuard adds specific water consumption per liter alongside SEC
Verified changes become the new baseline for the next improvement