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Sustainability methodology: How LeanSuite estimates environmental impact

Three conversions from published documents: paper not printed to CO2e, kilowatt-hours not used to CO2e, and miles not travelled to CO2e. This page lists each factor with the exhibit it was read from, the unit conversions, the formulas, our own assumptions, a worked example, and what the estimates leave out. Customer figures follow one rule: they come from what the plant enters and are published only with that plant's consent.

See the estimate in the ROI calculator Lean and sustainability

The factors

One row per conversion factor, as printed in its source

Values are quoted in the unit the source uses. The metric conversions are in the assumptions below. Each source was opened and the value read from the document on the date shown.

Conversion factors used in LeanSuite environmental estimates
MetricFactorUnitSourceYearApplies to
CO2e avoided per short ton of office paper not made (source reduction)PAPER_OFFICE_SOURCE_REDUCTION7.95MTCO2E per short ton of paperUS EPA Waste Reduction Model (WARM) v16, Paper Products chapter Exhibit 3-7 and Exhibit 3-11, row Office Paper, net source reduction for the current mix of inputs. Checked 2026-09-28.2023Paper sheets avoided, in the ROI calculator and the app's paper-pages field
Manufacturing-only share of the office paper factor (excludes forest carbon storage)PAPER_OFFICE_MANUFACTURING_ONLY0.99MTCO2E per short ton of paperUS EPA Waste Reduction Model (WARM) v16, Paper Products chapter Exhibit 3-11, row Office Paper, column Raw Material Acquisition and Manufacturing for Current Mix of Inputs. Checked 2026-09-28.2023Reference only, shown on the methodology page; used by no calculator
CO2e per MWh of US grid electricity (national annual total output rate)ELECTRICITY_US_GRID_CO2E770.9lb CO2e per MWhUS EPA eGRID2023 summary tables Table 1, Subregion Output Emission Rates, row U.S., annual total output emission rate, CO2e column. Checked 2026-09-28.2023Kilowatt-hours saved, in the app's energy field; no site calculator has a kWh input today
CO2 per vehicle-mile (passenger car), combustion onlyTRAVEL_CAR_CO20.297kg CO2 per vehicle-mileUS EPA GHG Emission Factors Hub 2025 Table 10, row Passenger Car. Checked 2026-10-21.2025Trips replaced, in the base numbers block (CH4 0.0059 g and N2O 0.0053 g per vehicle-mile are added as CO2e)
CO2 per passenger-mile (flight under 300 miles), combustion onlyTRAVEL_AIR_SHORT_CO20.207kg CO2 per passenger-mileUS EPA GHG Emission Factors Hub 2025 Table 10, row Air Travel - Short Haul (< 300 miles). Checked 2026-10-21.2025Trips replaced, in the base numbers block (CH4 0.0064 g and N2O 0.0066 g per passenger-mile are added as CO2e)
CO2 per passenger-mile (flight, 300 to 2,300 miles), combustion onlyTRAVEL_AIR_MEDIUM_CO20.129kg CO2 per passenger-mileUS EPA GHG Emission Factors Hub 2025 Table 10, row Air Travel - Medium Haul (>= 300 miles, < 2300 miles). Checked 2026-10-21.2025Trips replaced, in the base numbers block (CH4 0.0006 g and N2O 0.0041 g per passenger-mile are added as CO2e)
CO2 per passenger-mile (flight over 2,300 miles), combustion onlyTRAVEL_AIR_LONG_CO20.163kg CO2 per passenger-mileUS EPA GHG Emission Factors Hub 2025 Table 10, row Air Travel - Long Haul (>= 2300 miles). Checked 2026-10-21.2025Trips replaced, in the base numbers block (CH4 0.0006 g and N2O 0.0052 g per passenger-mile are added as CO2e)
100-year global warming potential of methaneGWP_CH4_AR528kg CO2e per kg CH4US EPA GHG Emission Factors Hub 2025 Table 11 (Global Warming Potential), row Methane, IPCC AR5. Checked 2026-10-21.2025Turning the methane in the travel factors into CO2e
100-year global warming potential of nitrous oxideGWP_N2O_AR5265kg CO2e per kg N2OUS EPA GHG Emission Factors Hub 2025 Table 11 (Global Warming Potential), row Nitrous oxide, IPCC AR5. Checked 2026-10-21.2025Turning the nitrous oxide in the travel factors into CO2e
Life cycle footprint of a tablet, smallest configuration, over its use periodTABLET_FOOTPRINT_LOW74kg CO2e per deviceApple iPad (A16) Product Environmental Report Greenhouse gas emissions panel, total product footprint, iPad (A16) base configuration. Checked 2026-10-21.2025The devices-you-add line in the base numbers block (low end)
Life cycle footprint of a tablet, largest configuration, over its use periodTABLET_FOOTPRINT_HIGH86kg CO2e per deviceApple iPad (A16) Product Environmental Report Greenhouse gas emissions panel, configuration table, 512GB. Checked 2026-10-21.2025The devices-you-add line in the base numbers block (high end)
Years of use Apple assumes for iPadOS devicesTABLET_USE_YEARS4yearsApple iPad (A16) Product Environmental Report Methodology notes, Use: a four-year period for macOS, iPadOS and tvOS devices. Checked 2026-10-21.2025Spreading the tablet footprint over a year of use
CO2e from one mile in an average US passenger vehicleEQUIV_VEHICLE_MILE0.000393metric tons CO2e per mileUS EPA Greenhouse Gas Equivalencies Calculator, calculations and references Passenger vehicles per year: 3.93 x 10-4 metric tons CO2e/mile. Checked 2026-10-21.2024The miles-driven comparison under the base numbers results
CO2 taken up by one urban tree in a year, as EPA models itEQUIV_URBAN_TREE_YEAR0.06metric tons CO2 per urban tree planted per yearUS EPA Greenhouse Gas Equivalencies Calculator, calculations and references Tree seedlings grown for 10 years: 0.060 metric ton CO2 per urban tree planted per year. Checked 2026-10-21.2024The tree-years comparison under the base numbers results

Three conversions, one shape

  • Paper not printed, in kg8.7634 kg CO2e per kgCO2e avoided
  • Electricity not used, in kWh0.3497 kg CO2e per kWhCO2e avoided
  • Car miles not driven0.297 kg CO2 per vehicle-mile, plus CH4 and N2OCO2e avoided
Each estimate multiplies what a plant did not use by one published factor. The travel factor adds methane and nitrous oxide as CO2e; the factor rows above say where each number comes from.

Paper, in metric

7.95 MTCO2E per short ton x 1,000 kg per tonne / 907.18474 kg per short ton = 8.7634 kg CO2e per kg of paper. One 5 g sheet is therefore 43.8 g CO2e.

Of the 7.95, 0.99 is raw material acquisition and manufacturing and 6.96 is forest carbon storage (WARM Exhibit 3-11). Manufacturing only would be 1.091 kg CO2e per kg.

Electricity, in metric

770.9 lb per MWh x 0.45359237 kg per lb / 1,000 kWh per MWh = 0.3497 kg CO2e per kWh. So 1,000 kWh not used avoids 350 kg CO2e.

This is the US national annual rate. The same eGRID table gives a rate for each grid subregion, and a plant's own subregion is the right one to use when its location is known.

Assumptions

The numbers that are ours, with the arithmetic

These are not from a source. They are stated so anyone can swap in their own paper weight or page count and redo the sums.

Weight of one sheet
5 g
80 gsm A4: 0.210 m x 0.297 m = 0.06237 m2 x 80 g/m2 = 4.99 g. 20 lb (75 gsm) US Letter: 8.5 in x 11 in = 0.06032 m2 x 75 g/m2 = 4.52 g. Both rounded to 5 g.
Pages per paper document
1 (you can change it)
One form, log or checklist is assumed to be one printed side. The ROI calculator has a field to change this; the sheets figure scales with it.
Short ton to kilograms
907.18474 kg
WARM factors are per short ton (2,000 lb). 1 lb = 0.45359237 kg, so 2,000 lb = 907.18474 kg.
Pound to kilograms
0.45359237 kg
eGRID rates are in lb per MWh. 1 lb = 0.45359237 kg and 1 MWh = 1,000 kWh.

Worked example (the ROI calculator's defaults, not a customer)

Example numbers

CO2e avoided = documents × pages per document × grams per sheet × kg CO2e per kg of paper

  1. Documents a year =75 paper documents a day x 250 operating days= 18,750 documents
  2. Sheets =x 1 page per document= 18,750 sheets
  3. Paper =x 5 g a sheet= 93.75 kg of paper
  4. CO2e =x 8.7634 kg CO2e per kg= 822 kg CO2e avoided a year
Avoided a year822 kg CO2e
Rounding: figures are computed in full precision and rounded only when shown. Sheets are whole numbers; CO2e shows one decimal under 100 kg and whole kilograms or tonnes above.

Base numbers

The example plants and formulas behind the starting estimate

The base numbers block on the sustainability page gives a starting estimate to a reader who does not know their own counts. Every input is editable. Every answer is a range. Nothing here is a customer figure or a measurement.

  1. 1. Forms filled in a year

    forms each shift x shifts a day x operating days + forms each day x operating days + forms each week x 52 + forms each month x 12 + forms each year

    Calendar arithmetic on the counts you enter. 250 operating days is 5 days x 50 weeks.

  2. 2. Sheets not printed

    forms a year x printed pages per form x share moved to a screen

    The low end uses the fewest pages and the lowest share. The high end uses the most pages and the highest share. One printed side is one page, and one page is one sheet.

  3. 3. Paper weight

    sheets x 5 g / 1,000

    An 80 gsm A4 sheet is 4.99 g and a 20 lb US Letter sheet is 4.52 g, rounded to 5 g.

  4. 4. Paper CO2e

    kg of paper x 0.99 x 1,000 / 907.18474 (low) to kg of paper x 7.95 x 1,000 / 907.18474 (high)

    EPA WARM v16, office paper not made. The low figure is raw material and manufacturing only. The high figure is EPA's net factor, which also counts forest carbon storage.

  5. 5. Trips and distance

    trips a year x share a record or video covers x round-trip miles (x people flying)

    The low end uses the lowest share and the high end the highest. Kilometres are divided by 1.609344. People flying only applies to the flight factors, which are per passenger; a car counts once.

  6. 6. Travel CO2e

    miles x (kg CO2 + g CH4 x 28 / 1,000 + g N2O x 265 / 1,000) per mile

    EPA GHG Emission Factors Hub 2025, Table 10 for the factors and Table 11 for the warming potentials. Combustion only.

  7. 7. Devices you add

    tablets x 74 / 4 (low) to tablets x 86 / 4 (high) kg CO2e a year

    Apple's published life cycle footprint for one tablet model, spread over the four years of use Apple assumes. A stand-in, not a LeanSuite figure. Enter 0 if you would use tablets you already own.

  8. 8. Net

    low: paper low + travel low - devices high. High: paper high + travel high - devices low

    The low end can be below zero. That means the devices could cost more than the paper and trips save, at the cautious end.

  9. 9. For scale

    paper and travel CO2e in tonnes / 0.000393 = miles in an average passenger vehicle; / 0.06 = urban tree-years

    EPA's equivalency factors. They put the size in everyday terms. They are not a saving and not a count of trees.

The three example plants, worked out (round numbers we chose, not averages and not customers)

The three example plants in the base numbers block and what the formulas give for each
PlantForms a yearSheets not printedPaper CO2eTrips CO2eTabletsNet CO2e
Small plant2,420about 1,200 to 4,800about 6.6 to 210 kg CO2eabout 36 to 110 kg CO2eabout 37 to 43 kg CO2eabout -0.57 to 280 kg CO2e
Mid-size plant8,060about 4,000 to 16,000about 22 to 710 kg CO2eabout 90 to 270 kg CO2eabout 110 to 130 kg CO2eabout -17 to 860 kg CO2e
Large plant22,920about 11,000 to 46,000about 0.063 to 2 t CO2eabout 210 to 640 kg CO2eabout 280 to 320 kg CO2eabout -0.045 to 2.4 t CO2e

Every plant assumes one to two printed pages a form, 50 to 100 percent of forms moved to a screen, car trips of 300 miles round trip with 10 to 30 percent covered by a record or video, and the tablets shown in the block. Weeks a year is 52 and months a year is 12. The low end of the net can be below zero: at the cautious end the tablets can cost more than the paper and trips save. In these three examples the paper's CO2e is small. Your own counts decide whether it is in yours.

What is not counted

The estimate is narrower than a footprint

Each line is something a reader might assume is included. None of it is.

  • Printing: printer and copier electricity, toner and ink, and the paper's trip from the mill to the plant.
  • The digital side: servers, networks and software hosting, and the power devices draw in use beyond what a tablet's life cycle figure includes. The estimator on /sustainability ignores devices. The base numbers block counts only the tablets you enter, from Apple's published life cycle figure for one tablet model.
  • Disposal: the paper factor is for paper not made (source reduction). Landfill, recycling or shredding of paper that was printed is not modelled.
  • Location: the electricity factor is the US national average. A plant in a coal-heavy or hydro-heavy grid subregion avoids a different amount per kWh.
  • Water, scrap, hours and dollars: none of these is converted to CO2e anywhere on the site. Travel is converted only in the base numbers block, from distance, and counts fuel burned (tank-to-wheel), not the fuel's production or the rest of the trip.
  • Anything the calculator did not ask for: no uplift, industry multiplier or maturity factor is applied to the environmental figures.

Customer figures

Where a plant's impact numbers come from, and when they are published

The calculators on this site estimate from what a visitor types. Impact figures in the LeanSuite product follow stricter rules.

  1. 1

    Entered, never estimated

    A figure exists only when the plant recorded it on a Kaizen or project: kilowatt-hours from a meter, kilograms of scrap from a scale, pages from the forms it stopped printing. Where a record does not exist, nothing is estimated in its place.

  2. 2

    Factor and version beside every number

    Each converted figure shows the factor it used, the source edition and the exhibit or table, exactly as this page does, so a sustainability team can check it or replace it with their auditor's factor.

  3. 3

    Consent before publication

    Nothing about a plant is published without that customer's written consent. Aggregates across customers, with no customer named, include only accounts that have switched that on, and stay off until they do.

  4. 4

    Sample data is always labelled

    Any report or screen shown before real figures exist carries a sample-data label in the header and the footer, and no sample figure is ever presented as a result a customer achieved.

The estimator on the sustainability page uses only the numbers a visitor types in, under these rules. In the product, a figure starts on a Kaizen or a project in the CI portfolio. Related reading: EPA's WARM and eGRID pages. Looking for funding rather than factors? See government grants and tax credits for manufacturers.

FAQs

Questions about the estimates

  1. No. They are estimates of the emissions avoided by two specific things: paper not printed and kilowatt-hours not used. They leave out printing, devices, hosting, transport, water and scrap, and they apply national average factors. A footprint or an ESG disclosure needs the plant's own inventory and its auditor's factors.

  2. EPA WARM's source reduction factor for office paper is 7.95 MTCO2E per short ton, of which 0.99 is raw material acquisition and manufacturing and 6.96 is forest carbon storage, EPA's estimate of the extra carbon that stays in forests when less pulpwood is demanded. We quote the full factor because it is the one WARM publishes for source reduction, and we show the manufacturing-only share beside it so anyone who excludes forest carbon can redo the arithmetic.

  3. Because the block counts the tablets you add as well as the paper and trips you avoid, and each is a range. At the cautious end, a few tablets over a year can add more than a plant's paper saves. We show that instead of hiding it. Enter 0 tablets if you would use devices you already own.

  4. None yet. The ROI calculator has no kilowatt-hour input, so it shows no electricity figure. The factor listed here is the one the LeanSuite app is specified to use for the energy field on a Kaizen, and the app should use the plant's eGRID subregion rather than the national average.

  5. Only with your consent. Impact figures in the product come from what your plant enters (kilowatt-hours, kilograms of scrap, pages of paper) and stay inside your account. An aggregate across customers, with no customer named, is published only for customers who have switched that on, and any figure that names a customer needs that customer's written approval first.

  6. When the source publishes a new edition. EPA releases eGRID roughly yearly and WARM every few years. Each factor on this page records the edition, the exhibit or table it was read from and the date it was checked, and a change to a factor changes every estimate on the site and in the app at once.

See the estimate with your own numbers

The ROI calculator shows sheets of paper and CO2e avoided from your document count, with these factors underneath. No sign-up needed for the estimate.

Open the ROI calculator