Measure before you cut
You cannot prove a saving, or a safe one, without a baseline. This is the order of work, the data you need first and where hospitals usually go wrong.
Last reviewed: November 5, 2026. Informational guidance written by Tariq Khurshaidi; see the terms of use.
Matching tools: EUI benchmark, carbon footprint, toolkit EUI sheet.
Who owns it
The facilities or energy manager owns the baseline. Finance supplies bills, clinical engineering supplies medical gas and equipment lists, and the infection prevention team signs off on any metering work that opens ceilings, shafts or pipework in occupied areas.
Data you need first
- Twelve consecutive months of electricity, natural gas, steam, chilled water and fuel oil, by building and by meter, from bills and utility portals.
- Floor area by building (gross square feet), licensed and staffed beds, and occupied bed-days or patient days per month.
- Weather data for the same months (heating and cooling degree days from a nearby station).
- Asset lists for chillers, boilers, air handlers, major pumps and medical gas plant, with nameplate data and any existing sub-meters.
- Refrigerant and gas purchases: refrigerant top-ups by asset, inhaled anesthetic purchases by agent, nitrous oxide deliveries and cylinder counts.
Sequence
- Set the boundary. List the buildings, leased space and shared plant that are in scope, and who pays for each utility. Write the rule for shared plant allocation down before you start.
- Normalize the energy. Convert to one unit (kBtu) and compute site EUI per building. Weather-normalize heating and cooling, and track a second intensity per occupied bed-day, because hospitals scale with activity, not only with area.
- Count Scope 1 and 2. Use the GHG Protocol: purchased electricity with an eGRID subregion factor, on-site fuel, refrigerant leakage and anesthetic gases. The carbon footprint calculator does this in one pass and shows which source dominates.
- Sub-meter the big loads. Chillers and chilled water plant, major air handlers, boilers or steam, central medical gas compressors, imaging suites and operating room air handling. Start with the three loads that look largest on the bill.
- Audit. An ASHRAE Level 2 audit turns the baseline into costed measures. Then adopt an energy management system (for example ISO 50001) so the savings survive staff changes.
- Report one KPI set every month: kBtu per square foot per year, kBtu per occupied bed-day, tCO₂e per square foot, plant kW per ton.
Worked example
A campus of 1,000,000 ft² uses 40,000,000 kWh and 800,000 therms in a year. Electricity is 40,000,000 × 3.412 = 136,480,000 kBtu. Gas is 800,000 × 100 = 80,000,000 kBtu. Total 216,480,000 kBtu, so site EUI is about 216 kBtu/ft²/yr. Enter the same numbers in the EUI benchmark to compare with the ENERGY STAR median for hospitals, then in the carbon footprint calculator to see Scope 1 against Scope 2.
The usual failure
A baseline built from one summer, one meter or one department. A second one: counting electricity and gas but forgetting refrigerant top-ups and anesthetic gases, which are Scope 1 and can be larger than people expect. A third: claiming a saving without adjusting for weather and patient volume, so a hot year looks like an efficiency failure and a mild year looks like a win.