# What does the Tiruppur manual's improved chulha save for one unit and for all 56, and do the totals add up?

Canonical: https://senseible.earth/answers/tiruppur-improved-chulha-56-units-total-checked

The Bureau of Energy Efficiency (BEE) Tiruppur manual lifts a bleaching chulha from 15% to 30% efficiency, halving 45 tonnes of wood to about 22 tonnes a year for rupees (Rs) 25,000. Across 56 chulhas it books 1,232 tonnes and Rs 36.96 lakh (1 lakh = 100,000). Per unit it uses Rs 3,600 a tonne; for the total, Rs 3,000.

## Why a chulha is only 15% efficient

- The test: 1,500 litres heated from 30 to 90 degrees Celsius (C) is 90,000 kilocalories (kcal) of heat output. Firewood used 150 kilograms (kg) at 4,000 kcal a kilogram is 600,000 kcal in. 90,000 / 600,000 = 15%.
- Bleaching 200 kilograms of yarn a day takes 150 kilograms of wood, 0.75 kilograms of wood for each kilogram of yarn.
- The manual lists the causes: no air circulation or smoke removal, heat lost through the grate openings, no control on air supply, radiation from all sides and no monitoring of wood feeding.

## The saving for one unit

The improved design, developed by Winrock International India, has a damper, an optimised furnace area, a better grate, use of heat in the flue gas and a chimney, and the manual puts its efficiency at around 30%. Wood falls by 1 minus 15/30 = 50%.

Present wood 45 tonnes a year (150 kilograms a day, which implies 300 days). Saved: 22.5 tonnes, printed as 22. Money printed: Rs 81,000, which is 22.5 x Rs 3,600. Investment Rs 25,000, payback 25,000 / 81,000 = 0.31 years, about 3.7 months, printed as 4.

## The 56 unit total, and why it differs

- Total wood 22 x 56 = 1,232 tonnes, as printed. Investment 56 x Rs 25,000 = Rs 14 lakh, as printed.
- Rs 81,000 x 56 would be Rs 45.4 lakh, but the manual prints Rs 36.96 lakh. That is exactly 1,232 tonnes x Rs 3,000. Our reading: the unit figure fits Rs 3,600 a tonne, the cluster figure fits Rs 3,000, and the summary table's third figure, Rs 0.77 lakh a unit, fits 22 x Rs 3,500. The manual prints no wood price here.
- Cluster payback: 14 / 36.96 = 0.38 years, about 4.5 months. Using the manual's own cost table, which puts an improved chulha at Rs 0.56 lakh in total with civil work, 56 x 0.56 = Rs 31.4 lakh and the payback is about 10 months.
- The efficiency claim: the manual says 25 to 30% cuts the energy bill by more than 50%. At 25% the cut is 1 minus 15/25 = 40%; only at 30% is it 50%.

## Put it to work

Weigh the wood per batch and the yarn bleached for a week before you build. If your chulha burns more than 0.75 kilograms of wood per kilogram, the saving is larger; if you already have a chimney and damper, it is smaller. The manual's wood is treated as non-renewable; report your own wood as tonnes bought and its carbon dioxide (CO2) as biogenic under the Greenhouse Gas Protocol's rule.

## The unit and cluster sums, side by side

- Unit: 150 kg x 300 days = 45 tonnes; x 50% = 22.5 tonnes; x Rs 3,600 = Rs 81,000; 25,000 / 81,000 = 0.31 years = 3.7 months
- Cluster: 22 x 56 = 1,232 tonnes; x Rs 3,000 = Rs 36.96 lakh; 56 x 25,000 = Rs 14 lakh; 14 / 36.96 = 0.38 years = 4.5 months
- Cost table: 56 x Rs 0.56 lakh = Rs 31.36 lakh; 31.36 / 36.96 = 0.85 years = 10.2 months

Rs 3,600 is also the wood price in the manual's solar table. The reading that the unit and cluster lines use different prices is ours, from the arithmetic.

## What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so wood bought each month is on file before and after a chulha change. Wood stays its own fuel line, and yarn bleached comes from your register.

- [Efficient chulha: wood saving for dyeing](https://senseible.earth/answers/efficient-chulha-dyeing-wood-saving)
- [Tiruppur solar hot water report checked](https://senseible.earth/answers/tiruppur-solar-hot-water-1000-litre-report-checked)
- [Tiruppur dyeing unit firewood boiler emissions](https://senseible.earth/answers/tiruppur-dyeing-unit-firewood-boiler-emissions)
- [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), [GHG Protocol Corporate Accounting and Reporting Standard, Scope 1 definition](https://ghgprotocol.org/sites/default/files/standards/ghg-protocol-revised.pdf)

Last reviewed 2026-11-05. Figures are from the manual's study year (around 2010 to 2011). Wood prices and chulha costs have changed; check a current build quote.