Does dyeing polyester use more energy per kilogram than dyeing cotton, and how much of it is electricity?
The Bureau of Energy Efficiency (BEE) Pali manual puts total dyeing energy at about 11 kilowatt hours (kWh) a kilogram for cotton, of which about 2 is electricity, and 11 to 18 for polyester, of which 1 to 2 is electricity. Polyester's extra is heat, in our reading.
The manual's numbers
- Cotton dyeing: total specific energy about 11 kWh a kilogram; electricity about 2.
- Polyester dyeing: total 11 to 18 kWh a kilogram; electricity about 1 to 2.
- Stage benchmarks it quotes from the International Textile Manufacturers Federation (ITMF) Annual Conference Report 2007: knitting 1.2 kWh a kilogram, ring spinning of combed yarn 6.0, weaving 6.2 and finishing 17.9. The manual does not say which energy forms these cover.
- Why the machines differ, as the manual says: dyeing of polyester has a requirement of tensionless processing and, "Consequently, machines like Jet Dyeing, Air Jet Dyeing etc have been devised".
What the gap is made of
Subtract electricity from total and the heat part is about 9 kWh a kilogram for cotton and 9 to 17 for polyester. Cotton sits at the bottom of the polyester range. Our arithmetic and reading: the extra energy in polyester dyeing is heat, because the electricity figures are about the same, 1 to 2 against about 2.
In kilowatt hours a metre at 100 grams a metre (the Pali manual says its cluster's fabric is mostly below 100 grams a metre), cotton is about 1.1 and polyester 1.1 to 1.8. At 0.675 kilograms (kg) of carbon dioxide (CO2) a kWh for financial year (FY) 2025-26, the electricity part alone is 1.35 kilograms a kilogram of cotton and 0.68 to 1.35 for polyester. The heat part depends on the fuel and is not in that number.
Using it fairly
- A range of 11 to 18 for polyester is wide because the machine, liquor ratio, shade depth and fuel all differ. Do not quote 18 or 11 for your own fabric; measure.
- To compare cotton and polyester on your own site, divide one month's fuel energy plus electricity by kilograms dyed, for each fibre separately, and keep the shade mix the same.
- For a fibre level footprint, this is only the dyeing step. Fibre growing or polymer making, spinning and weaving come before it; the page linked below shows a fair way to compare.
Two dye runs, per kilogram
- Cotton: 11 kWh total = 39.6 megajoules (MJ) = about 9,460 kilocalories (kcal) a kg; electricity 2 x 0.675 = 1.35 kg CO2
- Polyester: 18 kWh total = 64.8 MJ = about 15,480 kcal a kg; electricity 2 x 0.675 = 1.35 kg CO2, or 1 x 0.675 = 0.68
- Heat part: cotton 11 minus 2 = 9 kWh; polyester 18 minus 1 = 17 kWh
- At 100 g a metre: cotton 11 x 0.1 = 1.1 kWh a metre; polyester 18 x 0.1 = 1.8
The 11, 18, 2 and 1 are the manual's. The conversions, the subtraction and the per metre figures are our own arithmetic.
What Senseible does here
Senseible reads fuel invoices and electricity bills into monthly records, so one month's fuel and kWh can be divided by the kilograms you dyed for each fibre. The fibre split comes from your batch records.
- Cotton or polyester: which is lower carbon?
- Pali polyester saree printing: heat per kg
- Pali manual: dyeing energy per tonne by machine
- Higg FEM energy and emissions data
- Free calculators
Last reviewed 2026-11-05. The manual quotes its figures without a year for the dyeing totals and from a 2007 ITMF report for the stage benchmarks. Treat them as typical ranges and replace them with your own metered figures.