Mass times specific heat times the drop
There is only one equation in the first half of this page and it has no wine in it. 5,000 litres at 0.99 kg/L is 4,950 kg. A drop from 60F to 26F is 34 Fahrenheit degrees, which is 18.89 kelvin, because a Fahrenheit degree is five ninths of a kelvin — the single most common mistake in this arithmetic and worth checking on any figure that came out of a spreadsheet somebody else built.
4,950 kg times 3.8 kJ per kg per kelvin times 18.89 K is 355,300 kJ, or 98.7 kWh of cooling, or 336,759 BTU. That is 28.06 ton-hours of refrigeration for one tank, which is why cold stabilisation gets scheduled around the ferments rather than alongside them.
The share field is the honest one
A 10 ton plant is 35.2 kW on paper. During harvest most of it is holding ferments down, and the fraction left over is what actually pulls a stabilisation tank. At 60 percent that is 21.1 kW, and 0.8 kW of leak-back through the shell takes it to 20.3 kW net. 355,300 kJ at 20.3 kW is 4.86 hours.
Set the share to 100 percent and it is 2.87 hours. Set it to 15 percent and the plant delivers 5.28 kW against 0.8 kW of leak-back, and the tank takes 22.05 hours. Set it low enough and the leak-back wins outright and the tank never gets there at all, which the page says plainly rather than printing a large number. That is not a hypothetical: it is September in a warm cellar.
The hold is often the bigger job
Ten days at 0.8 kW of leak-back is 192 kWh of cooling, against 98.7 for the pull-down. Nearly two thirds of the total load is the tank simply sitting there, and none of it depends on how cold the wine was when it arrived. Insulation and a shorter hold are the two levers, and only one of them is a winemaking decision.
At a coefficient of performance of 2.5 the 290.7 kWh of cooling draws 116.3 kWh of electricity, which at 16 cents is 18.60 dollars. Per bottle that is 0.279 cents. Cold stabilisation is a slow job and a scheduling problem, and on this evidence it is not an expensive one — which is worth knowing before anybody optimises it.
What the lees keep
The second half of the page is volume, not energy. 1.5 percent left with the crystals and 1 percent at the filter afterwards is not 2.5 percent: it is 2.485 percent, because the filter only works on what came off the lees. On 5,000 litres that is 124.3 litres, or 166 bottles, or 13.8 cases.
The line underneath is the one that gets used most. To finish with 5,000 litres rather than start with them, you need 5,127 in the tank — 5,000 divided by the 0.98515 keep factor, not 5,000 plus 2.5 percent, which would leave you 2 litres short and is wrong in a way that gets worse the longer the chain.
Questions people ask
How much energy does it take to cold stabilise a tank of wine?
Mass times specific heat times the temperature drop, and nothing else. 5,000 litres at 0.99 kg/L dropping 34F is 4,950 kg times 3.8 kJ/kg/K times 18.89 K, which is 98.7 kWh of cooling or 336,759 BTU. Then the hold adds its own load: ten days of 0.8 kW leaking back is another 192 kWh, which is usually the larger number of the two.
Why convert Fahrenheit degrees to kelvin?
Because specific heat is quoted per kelvin and a Fahrenheit degree is five ninths of one. A 34F drop is an 18.89 K drop. Feeding 34 straight into the equation overstates the load by 80 percent, and it is the single most common error in cooling arithmetic — the more so because the answer still looks like a plausible number of kilowatt hours.
How long does a chiller take to pull a tank down?
The heat to remove divided by the net cooling reaching the tank, where net means the plant share less whatever leaks back in. 355,300 kJ at 20.3 kW net is 4.86 hours. The share is the field that decides it: the same plant at 15 percent instead of 60 takes 22.05 hours, and low enough that the leak-back matches it, the tank never arrives at all.
How much wine is lost to cold stabilisation?
Whatever stays with the tartrate lees when you rack, plus whatever the filtration afterwards keeps. At 1.5 and 1 percent that is 2.485 percent chained rather than 2.5 added, or 124 litres on a 5,000 litre tank — 166 bottles. Both figures are yours to measure; the lees loss depends on the tank shape and the racking valve height more than on the wine.
How much wine do I need in the tank to finish with 5,000 litres?
5,127 litres. Divide by the keep factor of 0.98515 rather than adding the loss percentage back on. Adding 2.5 percent to 5,000 gives 5,125 and leaves you two litres short, and the error grows with every stage you chain, which is why the page prints the division rather than the addition.