Does this work for a single school or a multi-campus group?

Both. Run it once per campus using that campus's meters and bills, then add the results together for a group total — the same way a company with several sites consolidates them. A single small school and a multi-campus international group use exactly the same arithmetic; only the number of times you run it differs.

Should I use term-time data or a full year?

A full year, if you can get it. Utility bills, transport contracts and waste collections usually run on calendar or financial-year cycles regardless of the academic calendar, so a July-to-June school year rarely lines up with a single set of bills. If you only have term-time figures, say so alongside the result and note that holiday-period energy use (heating a mostly empty building, security lighting) is usually smaller than term-time but not zero.

What counts as 'school transport' here?

Diesel burned in vehicles the school itself owns or leases and operates — a school-owned minibus fleet, for example. Contracted third-party bus operators are a purchased service, which belongs in Scope 3 rather than this Scope 1 field; if you pay an external operator, track their fuel separately or treat the contract as a spend-based estimate instead.

Why does electricity ask for a country but gas doesn't?

Electricity grids vary hugely by country because generation fuel mix varies hugely by country — see the pattern in our electricity calculator. Natural gas combustion, by contrast, produces close to the same CO2 per kWh burned wherever the boiler sits, so one global factor covers it without meaningfully losing accuracy.

Is this suitable for a university or only for schools?

The categories — electricity, gas, transport fuel, water, food waste, paper recycling — apply identically to a primary school, a secondary school, and a university campus; only the scale of the numbers changes. A university with labs, dormitories, and a larger vehicle fleet will want to run several campus buildings through this calculator separately and sum the results, the same way a company sums multiple sites.

Free calculator

School & campus carbon calculator

Convert electricity, gas, transport, water and waste into kgCO2e for a school or campus of any size — free, region-aware, with full provenance.

Country / regionElectricity (kWh)From the campus's electricity bill, for the period you're measuring.Natural gas (kWh)Heating and kitchen gas, if piped or metered in kWh.School-transport diesel (litres)Diesel for school-owned or -leased minibuses and vans, not contracted bus operators.Water supply (m³)Mains water supplied, from the water utility bill.Food waste to landfill (tonnes)Canteen and kitchen food waste sent to landfill, if not composted.Paper & board recycled (tonnes)Paper and cardboard sent for closed-loop recycling rather than landfill.

Prefer to skip the typing? Upload the bill instead — the numbers get read for you, three documents a day free.

How this calculation works

A school or campus is, from a carbon-accounting point of view, exactly like any other site: energy in, fuel burned, water used, waste out. Each line gets one multiplication:

Emissions (kgCO₂e) = quantity used × the factor for that activity

kWh of electricity multiplied by a grid factor, kWh of gas multiplied by a combustion factor, litres of diesel multiplied by a combustion factor, cubic metres of water multiplied by a supply factor, tonnes of waste multiplied by a disposal-route factor. None of this changes because the site teaches students instead of manufacturing widgets or selling insurance — the GHG Protocol's scope and category definitions don't distinguish by sector, and neither does this calculator.

Electricity is Scope 2, gas and school-owned vehicle diesel are Scope 1, and water and waste are Scope 3 (categories 1 and 5 respectively). For most campuses, electricity and gas dominate the total — classrooms, labs, kitchens, and often swimming pools and sports halls run heating, cooling, and lighting for long hours across a large floor area.

Term-time versus a full year

Schools run on an academic calendar; utility bills, waste contracts, and transport invoices usually don't. That mismatch is worth naming rather than ignoring.

If you can pull a full calendar or financial year of bills, use that — it captures holiday-period baseline energy use (security lighting, minimal heating, kitchen equipment left running) alongside the higher term-time load, and it lines up cleanly with how most reporting frameworks define their measurement period. If all you have is term-time data, the result will understate the true annual figure by whatever the holiday baseline adds — smaller than term-time consumption for most sites, but rarely zero, since buildings still need frost protection and security systems even when empty. Note which basis you used next to the result so anyone reading it later knows what it does and doesn't include.

The factors we apply

| Activity | Factor | Unit | Source | | --- | --- | --- | --- | | Electricity | country-specific, e.g. 0.4020 (Singapore, 2024) | kgCO₂e/kWh | EMA / Ember / EPA / DEFRA | | Natural gas | 0.18293 | kgCO₂e/kWh | DESNZ 2025 | | Diesel | 2.686 | kgCO₂e/litre | DESNZ 2025 | | Water supply | 0.1913 | kgCO₂e/m³ | DESNZ 2025 | | Food & drink waste, landfill | 700.30886 | kgCO₂e/tonne | DESNZ 2025 | | Paper & board, closed-loop recycling | 4.68568 | kgCO₂e/tonne | DESNZ 2025 |

The gap between food waste sent to landfill and paper sent to closed-loop recycling is worth staring at: landfilled food waste runs to 700.30886 kgCO₂e per tonne because it rots anaerobically and releases methane, while recycled paper's factor of 4.68568 reflects a processing emission, not a decomposition one. Diverting waste from landfill to recycling or composting is one of the largest, cheapest levers a campus has — the arithmetic below shows why.

A worked example

A secondary school with roughly 900 students pulls a full year of bills. Electricity came to 15,000 kWh for the month sampled (multiply by 12 for an annual estimate, or use the actual annual meter reading if you have it), gas for kitchen and heating came to 3,000 kWh, the school's own minibus used 400 litres of diesel, water supply was 500 m³, the canteen sent 2 tonnes of food waste to landfill, and the school recycled 1 tonne of paper and board.

Electricity (Singapore factor): 15,000 × 0.4020 = 6,030.0 kgCO₂e

Gas: 3,000 × 0.18293 = 548.8 kgCO₂e

Diesel: 400 × 2.686 = 1,074.4 kgCO₂e

Water: 500 × 0.1913 = 95.65 kgCO₂e

Food waste (landfill): 2 × 700.30886 = 1,400.6 kgCO₂e

Paper (recycled): 1 × 4.68568 = 4.7 kgCO₂e

Total = 6,030.0 + 548.8 + 1,074.4 + 95.65 + 1,400.6 + 4.7 = 9,154.1 kgCO₂e ≈ 9.15 tCO₂e

Electricity carries well over half the total, which is typical for campuses with long occupied hours and significant lighting and cooling load. Food waste sent to landfill is the second-largest line here despite being only 2 tonnes by weight — composting it instead of landfilling it would cut that line from 1,400.6 kgCO₂e to roughly 18.0 kgCO₂e (2 × 8.98311), a bigger single-category saving than switching the minibus to a smaller engine.

What this calculator doesn't cover

Contracted bus operators. Only diesel the school itself buys and burns counts here. Third-party school-bus contracts are a purchased service — either get their fuel figures directly or treat the contract spend as an estimate with the purchased goods & services calculator.
Boarding and residential energy use. If the campus includes dormitories, their electricity and gas are already captured in the same meters as the rest of the site — this calculator doesn't separate teaching space from residential space.
Clinical or laboratory waste. Science labs sometimes generate chemical or biological waste streams; there's no open-licensed factor for those, so keep them out of the general waste field rather than misclassifying them.
Refrigerant leaks from air-conditioning. Large campuses often run significant HVAC and cold-chain equipment; use the refrigerant & air-con leaks calculator for top-up records.
Staff and student commuting. A large share of a campus's true footprint is how people get there. Use the employee commuting calculator for staff, and treat student travel as a separate, usually much larger, exercise if you choose to measure it.

Where this fits in your reporting

Electricity here is Scope 2; gas and school-transport diesel are Scope 1; water and waste sit in Scope 3 categories 1 and 5. That mapping under the GHG Protocol doesn't change based on who runs the site — a school, a university, a company head office, and a government building all report the same categories the same way, which is what lets a school's number sit comfortably next to a company's in the same disclosure framework, whether that's ISSB IFRS S2, GRI 305, or a funder's own carbon questionnaire. Singapore-based schools reporting into a parent group or government scheme can check the SGX climate reporting deadlines guide for the listed-company timeline it stems from. When you'd rather hand over the actual bills than retype the numbers, upload them instead.

Sources

UK Government (DESNZ/DEFRA), Greenhouse gas reporting: conversion factors 2025 — gas, diesel, water, and waste factors (Open Government Licence v3.0): gov.uk/government/collections/government-conversion-factors-for-company-reporting
Energy Market Authority, Singapore Energy Statistics — Singapore grid emission factor (Singapore Open Data Licence): ema.gov.sg/resources/singapore-energy-statistics
Ember, Yearly Electricity Data — country generation intensities (CC-BY): ember-energy.org/data/yearly-electricity-data
GHG Protocol, Corporate Accounting and Reporting Standard — scope definitions: ghgprotocol.org/corporate-standard

Frequently asked questions

Does this work for a single school or a multi-campus group?: Both. Run it once per campus using that campus's meters and bills, then add the results together for a group total — the same way a company with several sites consolidates them. A single small school and a multi-campus international group use exactly the same arithmetic; only the number of times you run it differs.
Should I use term-time data or a full year?: A full year, if you can get it. Utility bills, transport contracts and waste collections usually run on calendar or financial-year cycles regardless of the academic calendar, so a July-to-June school year rarely lines up with a single set of bills. If you only have term-time figures, say so alongside the result and note that holiday-period energy use (heating a mostly empty building, security lighting) is usually smaller than term-time but not zero.
What counts as 'school transport' here?: Diesel burned in vehicles the school itself owns or leases and operates — a school-owned minibus fleet, for example. Contracted third-party bus operators are a purchased service, which belongs in Scope 3 rather than this Scope 1 field; if you pay an external operator, track their fuel separately or treat the contract as a spend-based estimate instead.
Why does electricity ask for a country but gas doesn't?: Electricity grids vary hugely by country because generation fuel mix varies hugely by country — see the pattern in our electricity calculator. Natural gas combustion, by contrast, produces close to the same CO2 per kWh burned wherever the boiler sits, so one global factor covers it without meaningfully losing accuracy.
Is this suitable for a university or only for schools?: The categories — electricity, gas, transport fuel, water, food waste, paper recycling — apply identically to a primary school, a secondary school, and a university campus; only the scale of the numbers changes. A university with labs, dormitories, and a larger vehicle fleet will want to run several campus buildings through this calculator separately and sum the results, the same way a company sums multiple sites.