In a first-of-its-kind study, researchers from the University of Waterloo assessed a Canadian hospital bed to reveal its total environmental footprint and specific carbon emission hotspots.
Studying a 40-bed hospital in British Columbia over the 2019 fiscal year, the researchers identified energy and water use and purchasing of medical products as the hospital’s primary hotspots, accounting for over half of the yearly footprint, totalling 3500-5000 tons of CO2 equivalent.
One hospital bed was roughly equivalent to the carbon footprint of five Canadian households.
The researchers calculated the carbon footprint by assessing thousands of unique products purchased by hospitals and using a combination of statistical sampling and calculations of carbon intensity – CO2 equivalent per dollar spent – for the sampled products, employing a bottom-up approach to generate a more accurate account than a percentage estimate.
Using an organisational lifestyle assessment (O-LCA), the team estimated the total environmental footprint of the hospital to be:
- Global warming potential: 3500–5000 t CO2 eq. (with 95% confidence)
- Acidification potential: 12,000 kg SO2 eq.
- Eutrophication potential: 39,000 kg N eq.
- Ozone depletion potential: 0.62 kg CFC-11 eq.
- Smog formation potential: 160,000 kg O3 eq.
- Respiratory effects: 2600 kg PM2.5 eq.
- Human toxicity (carcinogenic): 0.56 CTUh
- Human toxicity (non-carcinogenic): 3.3 CTUh
- Ecotoxicity: 63,000,000 CTUe
- Fossil fuel depletion: 5,700,000 MJ surplus
Dr Alex Cimprich, from the School of Environment, Enterprise, and Development, explained that the new method brought an unprecedented level of comprehensiveness and detail to hospital emissions data that could equip administrative leaders to assess which improvements to focus on to meet their environmental commitments.
“In our work, we often find that the biggest environmental footprints are where you least expect them to be – as the adage goes: out of sight, out of mind,” Dr Cimprich said.
“The goal was to make hidden environmental footprints more visible so that we can start to manage them, and the results suggest that hospital sustainability initiatives need to look further to achieve deeper emissions reductions.
“Subject to confidentiality, we obtained a wealth of foreground data for the hospital—including data from the hospital’s environmental sustainability team on the physical quantities of energy and water used, and wastes generated, in the hospital’s operations.
“And from the hospital’s “supply-chains” dataset, financial statements, Facilities Maintenance and Operations team, Food Operations Manager, and contracted service managers; particularly for patient transportation along with hospital housekeeping, laundry, and linen services.”
The background processes for a total of approximately 200 goods and services were modelled using data from Ecoinvent 3.4, supplemented by a wide range of literature references, assumptions, and estimations.
“For the products in the ‘supply-chains’ dataset containing over 50,000 purchase records for the 2018 calendar year we identified 2927 unique products purchased—constituting the “population” for our statistical analysis,” Dr Cimprich explained.
“Using an aggregation of the hospital’s 218 expense accounts, we grouped these 2927 products into 20 categories, 4 of which are excluded from our statistical analysis for the reasons given in Supporting Information.
“Based on the respective sample, we then calculated the average environmental intensity for each product category, as opposed to environmentally extended input–output (EEIO) analysis, which is commonly used to estimate the environmental footprint of healthcare.”
EEIO combines aggregated econometric data on exchanges of goods and services between economic sectors with aggregated environmental data on the emissions profile of each sector.
“The novelty of our approach is that it combines process based LCA data for a statistically representative random sample of specific purchased products with financial data to scale the product LCAs to a hospital level,” Dr Cimprich said.
“Product cost data were used to express the environmental intensity of each product—in each of the 16 categories—in common units (e.g., kg CO2 eq. per dollar spent) – and while transportation of patients and products supplied to hospitals and hospital waste were visible areas of environmental concern, other more hidden areas had much bigger environmental footprints.”
“In particular, the broad and diverse category of ‘medical products,’ itself comprising 1683 unique products, or more than half of all unique products in the hospital’s ‘supply-chains,’ was among the largest contributors to most indicators, while the contribution of things like “office supplies,” on the other hand, was comparatively small.
“While a limited evidence base hampers our ability to draw broad conclusions about the degree of, or drivers of, variation in hospital environmental footprints, we observe that energy and water use, wastewater treatment, anaesthetic gas emissions, and the upstream production of other purchased goods and services (of which there may be thousands) are likely ‘hotspots.’”