University of Alberta Library (UAL)

Guanwen Zhang

UAL has 161 staff members including librarians and support staff. As the second largest research library in Canada, it offers a collection of over 7 million titles and 10 million volumes in both print and digital formats. UAL’s digital collections are vast and diverse, including Education and Research Archive (ERA), research data repositories (Dataverse), Audio and Video collection (Aviary), and digitized books, newspapers, maps and other special collections.

Before July 2025, UAL had an on-premise cloud acting as the backbone of its digital preservation practices. That cloud consists of 6 physical servers residing at three separate data centers. After July 2025, the private cloud had been decommissioned. UAL embraces a number of ways of accomplishing its digital preservation goals, which include Internet Archive (IA), community-owned Ontario Library Research Cloud (OLRC), Aviary Platform (commercial SaaS), and LOCKSS and CLOCKSS.

Looking at just their web archiving activities as listed in the table below:

They needed to calculate the following:

a) Total storage (D) in TB, in this case D=42.1TB

b) Power consumption per TB, this depends on the storage types: disks, and tapes etc. We take the average number P=5W/TB

c) Data center efficiency (PUE): This varies from region to region. For North America, we take PUE=1.5. (https://journal.uptimeinstitute.com/datacenter-energy-efficiency-by-region/, 2020)

d) Define the duration of data activity (T), usually, we use one year as a time unit for carbon footprint estimation. T=365 days * 24 hour/day

e) Carbon Intensity: For example, the carbon intensity of Canada is 174gCO₂/kWh, and North America is 374 gCO₂/kWh (https://ourworldindata.org/grapher/carbon-intensity-electricity, 2024). We assume the Carbon Intensity (CI)=400gCO₂/kWh=0.4kgCO₂/kWh

The estimate of carbon footprint for a single year is thus:

Estimated Carbon Emission = D*P*PUE*T*IC=42.3 * 5 * 1.5 * (365*24) * 0.4 =1112 kg CO₂/year