Short answer
Refrigeration accounts for 50 to 60 percent of total electrical consumption in a dairy processing plant. Its efficiency degrades gradually through condenser fouling, incorrect suction pressure, evaporator icing and poor part load control, and none of these raise an alarm because the product temperature stays within spec. Monitoring kW per tonne of refrigeration rather than total kWh is what makes the drift visible.
The load that never alarms
Every other major consumer in a dairy tells you when it is unhappy. A boiler trips. A pasteuriser diverts. A filler jams. Refrigeration does none of that. When a refrigeration plant becomes inefficient, it simply works harder and keeps the product exactly as cold as it was before. The only symptom is on the electricity bill, thirty to sixty days later, mixed in with everything else.
That matters more in dairy than in most industries, because refrigeration is 50 to 60 percent of total electrical consumption. Half the electricity bill is being spent by a system engineered never to complain.
The four ways a refrigeration plant quietly gets worse
01
Condenser fouling and airflow restriction
Scale, biofilm, dust and blocked fins raise condensing pressure. The compressor then works across a wider pressure ratio for the same cooling effect. This is the single most common efficiency loss in industrial refrigeration and it develops over weeks.
What it costsEvery additional degree of condensing temperature is a permanent percentage on the compressor power for as long as it goes uncorrected.
02
Suction pressure set lower than needed
Suction pressure is often set once, conservatively, to guarantee the coldest load in the plant. Every other load then runs colder than it needs to. Raising suction pressure where the load profile allows is one of the cheapest available savings, and it needs data to justify.
What it costsThe whole plant pays for the requirement of the single coldest circuit, all year.
03
Evaporator icing and poor defrost control
Ice on an evaporator insulates the surface it is meant to cool. Defrost cycles run on timers rather than on demand, so plants either defrost too often, adding heat load, or too rarely, running iced coils.
What it costsBoth failure modes cost energy continuously, and both are invisible from the cold store thermometer.
04
Part load and short cycling
Dairy load is highly cyclical, following intake, processing and CIP. Compressors sized for peak run heavily unloaded for much of the day, where efficiency is far worse, or short cycle against a badly tuned setpoint.
What it costsUnloaded running and short cycling waste energy and shorten compressor life at the same time.
Measure the ratio, not the total
Total refrigeration kWh is nearly useless as a management number, because it moves with production volume and with ambient temperature. A hot week and a heavy production week look identical on a kWh chart.
The number that carries signal is specific energy: kW per tonne of refrigeration, tracked against ambient and against load. Normalised that way, condenser fouling shows up as a slow upward drift that no seasonal explanation can account for, and it becomes a maintenance trigger rather than a surprise.
| Point | Why it matters |
|---|---|
| Compressor level electrical power | Attributes energy to the machine rather than to the whole motor control centre |
| Suction and discharge pressure and temperature | Gives pressure ratio and condensing approach, the two headline efficiency indicators |
| Chilled water or glycol flow and delta T | Converts to actual delivered tonnes of refrigeration, the denominator of the ratio |
| Condenser water flow, temperature and make up | Links refrigeration efficiency to the water side, including blowdown and make up volume |
| Run hours, load percentage and start counts | Exposes short cycling and unloaded running |
| Cold store temperature and door events | Separates a plant problem from a door left open, which is a different fix entirely |
The water side is part of the energy story
Refrigeration and water are not separate problems in a dairy. Evaporative condensers consume make up water and produce blowdown. If condenser water treatment slips, fouling follows, and the electricity bill rises. If make up is unmetered, the water loss is invisible too.
This is the practical argument for a single utility layer rather than a refrigeration monitoring product and a water monitoring product. The cause sits on one side of the boundary and the symptom on the other.
Where it fits with the rest of the plant
Refrigeration is 50 to 60 percent of electricity, and electricity is roughly 20 percent of a dairy's total energy, because around 80 percent goes to steam and hot water. That framing is worth holding on to. Refrigeration deserves attention because it is the biggest electrical load and the one that degrades invisibly, but a complete energy programme has to reach the boiler house too.
What percentage of dairy plant electricity is used by refrigeration?
Refrigeration accounts for approximately 50 to 60 percent of total electrical consumption in dairy processing plants. Separately, around 80 percent of a dairy's total energy consumption is used to generate steam and hot water, with the remaining 20 percent consumed as electricity across refrigeration, mechanical processes, ventilation and lighting.
How do you measure refrigeration efficiency in a dairy?
Track specific energy, expressed as kW per tonne of refrigeration delivered, rather than total kWh. That requires compressor level electrical measurement on one side and delivered cooling on the other, calculated from chilled water or glycol flow and temperature difference.
Normalise against ambient temperature and production load so that seasonal and volume effects do not mask genuine efficiency drift.
Why does refrigeration inefficiency go unnoticed?
Because the control system succeeds. A fouled condenser or an iced evaporator does not cause a temperature excursion, it causes the compressor to run longer and harder to hold the same setpoint. Product stays in spec, no alarm fires, and the additional cost appears only on an aggregated utility bill weeks later.
Can existing refrigeration controls be used instead of new sensors?
Often, partly. Many refrigeration control panels already hold pressures, temperatures and run states that can be read over Modbus or OPC UA and consumed directly. What is usually missing is compressor level electrical measurement and delivered cooling, and those gaps are filled with retrofit sensors.
