# How does the Bureau of Energy Efficiency (BEE) Tiruppur manual get 220 tonnes of wood saved from recovering heat in hot drained dye water?

Canonical: https://senseible.earth/answers/tiruppur-hot-drained-water-heat-recovery-report

BEE's Tiruppur manual takes 62,720 litres a day of dye house drain at 70 degrees Celsius (C), recovers 80% of the heat above 30 degrees C and burns 880 kilograms less wood a day. That is 220 tonnes a year, rupees (Rs) 6.6 lakh (1 lakh = 100,000), for Rs 6 lakh: 11 months.

## How the 880 kilograms a day is built

1. Dye per day: 1,400 kilograms (kg) a batch (the table lists six machines and does not say each or total) x 2 batches x 70% use = 1,960 kilograms a day, at a liquor ratio of 8 and 4 hot washes.
2. Hot water drained: 1,960 x 8 x 4 = 62,720 litres a day.
3. Heat in it: 62,720 x (70 minus 30) = 2,508,800 kilocalories (kcal) a day. The manual recovers 80%, 2,007,040 kcal.
4. Wood: 2,007,040 / 0.60 boiler efficiency / 3,800 kcal a kilogram = 880 kilograms a day.
5. Year: 880.28 x 250 days = 220,070 kilograms (the manual prints 880 for the rounded day), 220 tonnes, at Rs 3,000 a tonne = Rs 660,210 (220.07 x 3,000).

## Cost and payback

Investment Rs 600,000, so 600,000 / 660,210 = 0.91 years, about 11 months, as printed. The manual's cost table prices heat recovery units at Rs 4.92 lakh for 2 kilolitres an hour and Rs 6.56 lakh for 4 kilolitres an hour, so Rs 6 lakh sits between the two sizes.

## Where the report is cautious and where it is not

- The text says water leaves at 90 degrees C, but the table uses 70. At 90 degrees C the heat is 62,720 x 60 = 3,763,200 kcal, and the saving would be about 330 tonnes. The report uses the lower figure, which is the cautious one.
- The daily 1,960 kilograms equals one batch size x 2 x 0.70, though the table lists six machines. Our reading is that 1,400 kilograms is the total of the six; the table does not say.
- The 80% recovery and 60% boiler efficiency are assumptions, not measurements. At 40% recovery the saving halves. Fit two temperature probes and a flow count before you rely on 80%.

## What to put on file

- Wood or other fuel bought each month, weighed, from invoices and the stock register.
- Kilograms dyed each month, so fuel per kilogram can be compared before and after.
- Temperatures in and out of the exchanger on a few typical days.

## The report's heat sum

- Drain: 1,960 kg x 8 x 4 washes = 62,720 litres a day
- Heat: 62,720 x (70 minus 30) = 2,508,800 kcal; 80% = 2,007,040 kcal
- Wood: 2,007,040 / 0.60 / 3,800 = 880.28 kg a day (printed 880); x 250 days = 220,070 kg = 220 tonnes
- If the drain were 90 degrees C: 62,720 x 60 x 0.8 / 0.6 / 3,800 = about 1,320 kg a day, about 330 tonnes

Figures are the manual's. The 90 degrees C case is our own arithmetic from the manual's text, not a figure it prints.

## What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so the wood bought each month is on file to compare before and after a heat recovery fit. Temperatures and kilograms dyed come from your own logs.

- [Surat drain heat recovery reports compared](https://senseible.earth/answers/surat-drain-heat-recovery-reports-compared)
- [Dyehouse hot effluent heat recovery saving](https://senseible.earth/answers/dyehouse-hot-effluent-heat-recovery-saving)
- [Tiruppur soft flow dyeing machine report](https://senseible.earth/answers/tiruppur-soft-flow-dyeing-machine-report-payback)
- [Tiruppur manual: payback table in months or years](https://senseible.earth/answers/tiruppur-manual-payback-table-months-or-years)
- [Green loan readiness check](https://senseible.earth/green-loan-check)

Sources: [BEE, Manual on Energy Conservation Measures in Textile Cluster, Tirupur (prepared by Winrock International India, via SAMEEEKSHA)](https://sameeeksha.org/pdf/clusterprofile/Tirupur_Textile_Industries.pdf)

Last reviewed 2026-11-05. Figures are from the manual's study year (around 2010 to 2011), with wood at Rs 3,000 a tonne. Re-run with your own drain flow, temperature and fuel price.