Sustainability methodology: How LeanSuite estimates environmental impact
Two conversions, both from published US EPA documents: paper not printed to CO2e, and kilowatt-hours not used to CO2e. This page lists each factor with the exhibit it was read from, the unit conversions, 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.
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.
| Metric | Factor | Unit | Source | Year | Applies to |
|---|---|---|---|---|---|
| CO2e avoided per short ton of office paper not made (source reduction)PAPER_OFFICE_SOURCE_REDUCTION | 7.95 | MTCO2E per short ton of paper | US 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. | 2023 | Paper 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_ONLY | 0.99 | MTCO2E per short ton of paper | US 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. | 2023 | Reference 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_CO2E | 770.9 | lb CO2e per MWh | US EPA eGRID2023 summary tables Table 1, Subregion Output Emission Rates, row U.S., annual total output emission rate, CO2e column. Checked 2026-09-28. | 2023 | Kilowatt-hours saved, in the app's energy field; no site calculator has a kWh input today |
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)
- 75 paper documents a day x 250 operating days = 18,750 documents a year.
- x 1 page per document = 18,750 sheets.
- x 5 g a sheet = 93.75 kg of paper.
- x 8.7634 kg CO2e per kg = 822 kg CO2e avoided a year.
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.
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: the phones, tablets and servers that hold the digital forms, and the electricity they use.
- 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, transport, hours and dollars: none of these is converted to CO2e anywhere on the site.
- 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
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
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
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
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 example report on the sustainability page is sample data under these rules. Related reading: EPA's WARM and eGRID pages.
FAQs
Questions about the estimates
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.