Why does the Bureau of Energy Efficiency (BEE) Tiruppur manual save 30% of wood in a compacting boiler but 16% in a dyeing boiler?
BEE's Tiruppur manual swaps a 49% efficient compacting boiler for a 70% one and books 30% less wood, then a 58% dyeing boiler for a 70% one and books 16%. The first prints a payback of 0.8 years; its own cost and saving give 1.16.
The two cases side by side
- Compacting unit: boiler 200 kilograms of steam an hour, pressure 10.5 kilograms a square centimetre. Existing efficiency 49%, new 70% at 70% load. Wood 576 tonnes a year, 30% saved = 172 tonnes at rupees (Rs) 2,000 a tonne = Rs 3.44 lakh. Cost Rs 4.00 lakh. Printed payback 0.8 years.
- Dyeing unit: boiler 6,000 kilograms an hour. Existing efficiency 58%, new 70%. Wood 3,168 tonnes a year, 16% saved = 506.9 tonnes at Rs 3,000 = Rs 15.2 lakh. Cost Rs 30.0 lakh. Printed payback 2.0 years.
Why the saving differs: the efficiency gap
A boiler that turns more of the fuel into steam burns less for the same steam. The fuel saved is 1 minus the old efficiency divided by the new. Compacting: 1 minus 49/70 = 30%, exactly the manual's figure. Dyeing: 1 minus 58/70 = 17.1%, and the manual uses 16%, a little cautious. So the compacting boiler saves more because it starts far lower, at 49%. The manual's technical table lists the dyeing boiler at 75%, not the 70% used in its cost case; at 75% the saving would be 1 minus 58/75 = 23%.
The manual blames the low efficiency on two pass design, poor insulation, untreated feed water, no heat recovery from flue gas and no control of fuel feed, and says boilers with thermal efficiency of 75% are available in the market.
Two numbers that need a second look
- Compacting payback: Rs 4.00 lakh / Rs 3.44 lakh = 1.16 years, about 14 months, not 0.8. The manual's summary table prints 10 months, which matches 0.8 years. We could not find what gives 0.8. With the full cost of Rs 4.31 lakh in its cost table the payback is 1.25 years.
- The dyeing case uses a 6,000 kilogram an hour boiler costing Rs 30.0 lakh. The manual's cost table lists boilers of only 200 and 1,000 kilograms, and its technical table shows a 3,000 kilogram boiler. So the Rs 30.0 lakh has no second price in the manual to check against; get a quote.
Which case is yours
- Find your boiler's efficiency from a test, not the rating plate. The fuel saving follows the gap: 40% old efficiency to 70% saves 43%; 58% to 70% saves 17%.
- Weigh the wood for a month, with steam made or fabric processed, to set your baseline in tonnes.
Both cases from the printed lines
- Compacting: 576 x 0.30 = 172.8, printed 172 tonnes; 172 x Rs 2,000 = Rs 3.44 lakh; 4.00 / 3.44 = 1.16 years
- Dyeing: 3,168 x 0.16 = 506.9 tonnes x Rs 3,000 = Rs 15.2 lakh; 30.0 / 15.2 = 1.97 years
- Efficiency rule: saving = 1 minus old / new = 1 minus 49/70 = 30.0%; 1 minus 58/70 = 17.1%
Figures are the manual's at study-year prices; the 40% case is our own arithmetic.
What Senseible does here
Senseible reads fuel invoices and electricity bills into monthly records, so wood bought by the month is on file to set the baseline for a boiler swap. Boiler efficiency comes from a test by a competent tester; Senseible keeps the fuel bills before and after.
- Tiruppur dyeing unit firewood boiler emissions
- Surat 3 and 4 tonne boiler reports compared
- Boiler excess air fuel saving
- Tiruppur manual: payback table in months or years
- Green loan readiness check
Last reviewed 2026-11-05. Figures are from the manual's study year (around 2010 to 2011); wood prices and boiler costs have changed. Test your own boiler and get a current quote.