# Do translucent roof sheets really cut a small oil mill's lighting carbon?

Canonical: https://senseible.earth/answers/oil-mill-translucent-roof-sheet-saving

Yes, but the carbon is small: about 1.5 t CO2 a year. BEE's Alwar report puts 27 m2 of translucent sheet over a 90 m2 shed so 900 W of lamps stay off 8 hours a day, saving 2,160 kWh. Cost Rs 16,254, payback about 19 months at 2011 tariffs.

## The shed in the report

- Opaque roof over a 90 m2 working area, lit at about 100 W per 10 m2 with fluorescent tubes and 100 W bulbs: 900 W.
- Lamps on for the 8 daylight working hours, 300 days a year.
- Fix: replace 27 m2 of roofing, about 30% of the area, with translucent sheet and switch the lamps off by day.

## The sum, corrected

- Energy: 0.9 kW x 8 hours x 300 days = 2,160 kWh a year.
- At the report's Rs 4.8 a kWh that is Rs 10,368. The report writes Rs 9,700, and Rs 0.017 lakh in its summary; both are slips.
- Cost: Rs 11,610 of sheet, Rs 2,322 for taxes and fitting, Rs 2,322 contingency: Rs 16,254.
- Payback: 16,254 / 10,368 = 1.6 years, about 19 months. The report says 20.

## Why it is still worth doing

1.5 t is small next to what the kolhus and expellers use. The roof is cheap, though, and it also cuts lamp failures and lifts light levels where workers handle cake and oil. Do it when the roof is being repaired anyway, and spend the bigger effort on the expellers and drives.

## What decides the real saving

- Someone has to switch the lamps off. A daylight sensor or a separate switch for the lamps under the sheets makes it stick.
- Oil mist and dust film the sheets; clean them, or the light drops.
- If you have already moved to LED lamps, count their watts, not 900 W; the saving shrinks with them.

## One 90 m2 shed, one year

- 2,160 kWh x 0.675 = 1.46 t CO2
- The report says 1.9 t, on an older grid factor
- Per m2 of sheet: 2,160 / 27 = 80 kWh a year

Grid at CEA's FY 2025-26 factor, an estimate.

## What Senseible does here

Senseible reads your electricity bills into monthly records with CO2 for the units. A saving this size will barely show on a mill's bill, so its calculators are the quicker way to size it before you buy.

- [Senseible calculators](https://senseible.earth/calculators)
- [Factory skylights and lighting savings](https://senseible.earth/answers/factory-skylights-daylight-lighting-savings)
- [Efficient oil expeller: kWh saved](https://senseible.earth/answers/oil-mill-efficient-expeller-kwh-saving)
- [Alwar mustard oil mills: kWh per quintal](https://senseible.earth/answers/alwar-mustard-oil-mills-electricity-per-quintal)

Sources: [BEE, Detailed project report: translucent sheets in oil mills, Alwar oil mill cluster (2011, SAMEEEKSHA)](https://sameeeksha.org/pdf/dpr/Alwar_oil_mills_cluster/Energy_cost_reduction_with_translucent_sheet_Alwar_OM_cluster.pdf), [CEA CO2 Baseline Database, version 22.0](https://cea.nic.in/cdm-co2-baseline-view?mappingId=234&lang=en)

Last reviewed 2026-11-01. Report figures are from a BEE SME programme project report; costs are at the report year's prices.