How do I calculate a hospital's carbon footprint per bed, and what drives it?
Add Scope 1 (DG diesel, boiler and kitchen fuel, anaesthetic gases, refrigerant leaks) and Scope 2 (grid electricity from your bills) for a year, then divide by beds and by occupied bed-days. Report both. Start with the electricity bills: air conditioning, operating theatres and imaging run day and night.
What goes in Scope 1 and Scope 2
- Scope 1: diesel for DG sets, fuel for boilers and laundry, LPG or PNG for kitchens, nitrous oxide used in anaesthesia, and refrigerant top-ups for chillers and ACs.
- Scope 2: electricity bought from the discom or through open access, from twelve months of bills.
- Anaesthetic agents such as desflurane, sevoflurane and isoflurane are strong greenhouse gases but are not among the seven gases the GHG Protocol Corporate Standard requires. Report them as a separate line and say so; desflurane has by far the highest warming effect of the three.
Which denominator to use
- Per bed: easy to compare across years, but use the same bed count every time, either sanctioned or operational, and name it.
- Per occupied bed-day: beds x 365 x occupancy. It reflects how busy you were, so it falls when occupancy rises.
- Per square metre of floor area: useful for comparing buildings.
- A hospital with large outpatient, dialysis or diagnostic volumes will look worse per bed than one without; say what services you run.
What usually drives the number
- Air conditioning and chillers running all day for theatres, ICUs and wards.
- DG run hours where supply is unreliable.
- Imaging equipment and sterilisation.
- Nitrous oxide piped from a central manifold, which can leak even when unused.
- Scope 3: medicines, devices and consumables bought. Across the global health sector, Health Care Without Harm and Arup (Health care's climate footprint, 2019) put 71% of emissions in the supply chain. Estimating yours needs purchase data.
Do not compare with foreign benchmarks blindly
Per bed figures from other countries reflect different climates, grids and service mixes. Track your own figure year on year and compare like with like.
Worked example: a 200-bed hospital for one year (illustrative)
- Grid electricity: 3,000,000 kWh x 0.710 = 2,130,000 kg CO2
- DG diesel: 60,000 L x 2.68 = 160,800 kg CO2
- Kitchen LPG: 12,000 kg x 2.98 = 35,760 kg CO2
- Nitrous oxide: 500 kg x 273 (AR6 GWP) = 136,500 kg CO2e
- Total: 2,463,060 kg CO2e, about 2,463 t
- Per bed: 2,463 / 200 = 12.3 t CO2e
- Occupied bed-days at 75%: 200 x 365 x 0.75 = 54,750; 2,463,060 / 54,750 = 45.0 kg CO2e per bed-day
All quantities are illustrative. Refrigerants and volatile anaesthetic agents are left out of this example; add them from service invoices and purchase records.
What Senseible does here
Senseible reads electricity bills (period, tariff, sanctioned load, units; CEA grid factor 0.710 kg CO2 per kWh, version 21.0) and fuel invoices (IPCC 2006 defaults: diesel 2.68 kg per litre, LPG 2.98 kg per kg) into Scope 1 and 2, and reads refrigerant top-up invoices too.
- Diesel generator: Scope 1 or 2
- Refrigerant top-up invoice to CO2e
- Which intensity metric to use
- Footprint from electricity bills
Sources: GHG Protocol Corporate Accounting and Reporting Standard, CEA CO2 Baseline Database, 2006 IPCC Guidelines, Volume 2 Energy (diesel and LPG defaults)
Last reviewed 2026-10-19.