Aarhus Universitets segl

No. 509: Aarhus University Emissions Inventory 2021

Stridsland, T.D., Stounbjerg, A., Sanderson, H., Winter, M., Mikkelsen, M.H., Albrektsen, R. & Nielsen, O.-K. 2022. Aarhus University Emissions Inventory 2021. Aarhus University, DCE – Danish Centre for Environment and Energy, 42 pp. Scientific Report No. 509. http://dce2.au.dk/pub/SR509.pdf


This is Aarhus University’s (AU’s) internal greenhouse gas (GHG) inventory for 2021, under a slightly updated methodology, while still adhering to the Greenhouse Gas Protocol (GHGP). The methods used in this report reflect the development of corporate GHG inventory related research in both academic and non-academic spaces, resulting in updated and more clear definitions of the methods used. The 2021 inventory includes both attributional life cycle assessments (aLCA), and consequential life cycle assessments (cLCA) which are referred to as process based (PB) and spend based (SB), respectively. SB approaches are used for AU’s procurement due to the size and variety of purchased goods and services. For a visual representation of these results, see the visual summary below. This report expands the 2020 GHG inventory by more clearly defining what the different methods can and cannot be used for, and treating the results from different methods separately.

The PB method resulted in total scope 1, 2 and 3 emissions of 20,322.7 tCO2e, and a -1% change of comparable emissions from 2020. Total emissions between 2021 and 2020 show a -0.3% change, however 2021 includes more emission sources. Notable 2021 increases include university activities recovering from the effects of Covid-19 with a 35% increase in business flight emissions from 2020, and a higher emission factor (EF) for Danish electricity resulted in a 10% increase in emissions, despite a -1% change in consumption of kWh from 2020. A -19% change is seen in AU’s second largest emission source, investments (4,106.0 tCO2e), which, coupled with a partial reduction of EFs among on-site combustion of gas and oil, and a reduction in transport emissions, produces the overall static result for the 2021 GHG inventory.

Total PB emissions are down 37% from 2018, when AU first began disclosing emissions. Here, the impacts of Covid-19 are very clear, and blur any meaningful differentiation between the effects of Covid-19 and initiatives presented in the AU Climate Strategy. This is shown in the visual summary below.

The SB method resulted in total scope 3.1 (purchased goods and services) emissions of 35,823.1 tCO2e and scope 3.2 (capital goods) emissions of 3,868.8 tCO2e, using the model EXIOBASE. Since this method uses an updated and expanded scope, it is unable to be compared to 2020 spend based methods. EXIOBASE relies on economic data, (of which 87% of university spending is accounted for) and the results indicate which sectors that AU spend most within, and thereby which sectors contribute the most emissions to AU’s total inventory. Most impactful are AU’s spending within purchased goods concerning computers, devices and software at 2,375.6 tCO2e, pharmaceutical related purchases at 2,330.5 tCO2e and machinery and equipment at 2,039.0 tCO2e. Further, scope 3.2 (capital goods) are defined as longer use purchases such as buildings where the majority is allocated to the category “construction of buildings” at 3,103.8 tCO2e. At this point, using this method, we are unable to clearly define which specific purchases or suppliers within these categories are responsible for the greatest emissions.

Normalizing the PB data to tCO2e per person-year across employees, students and combined results in: 2.45 (tCO2e/employee-year); 0.75 (tCO2e/student-year), and combined 0.58 (tCO2e/total-AU-year), which is a 2%-4% decrease from 2020.

The methods used in this report are the result of a collaboration between all the Danish universities. Discussions in this space highlight the trade-offs between the aLCA and cLCA methods, and more specifically discourage the combination of results, as they be misguiding when considered as a sum. As a result, the methods are reported separately in this report, although individually, they present the foundation for climate related decarbonisation decision support in the future. Research on how best to navigate the differences and trade-offs is ongoing in the literature, however this should be seen as an example of how far the discussion has reached.