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GHG Inventories – Balancing Accuracy with Practicality

On July 28th, the Global Covenant of Mayors USA, along with ICLEI USA, held the webinar “GHG Inventories – Balancing Accuracy with Practicality”. The webinar was chaired by Calyn Hart of ICLEI USA, and counted on the participation of Michael Tavendale from Google EIE and city of Nashville representatives Michelle Hamman and Laurel Creech.The webinar provided a space for dialogue between cities and experts to support signatories reporting against the GCoM’s Common Reporting Framework (CRF)

Calyn Hart highlighted some of the accounting principles for a GHG Inventory within the CRF: “Inventories shall be relevant to the local situation, and local governments shall consider and report all emission sources.” Therefore, to the extent possible, all relevant activity data, data sources, and methodologies need to be documented “to allow for review, replication of good practice and tackling challenges” she concluded.

After covering basic requirements and guidelines, ICLEI also presented the most common mistakes made by cities when developing and reporting an inventory. Among these are incomplete inventories, when required data is not informed; missing attachments for activity data or emission factors; and lacking of submitting supporting documentation. 

One of the many challenges for cities is finding data and measuring emissions. Trying to close this gap led Google to create its Environmental Insights Explorer (EIE) to provide data to accelerate local climate action and inform city policies. Michael Tavendale introduced the EIE tool that provides insights across four key areas  – Building emissions, Transportation emissions, Rooftop solar potential and New data pilots (Tree Canopy & AQ) . “To measure this data, the program calculates the energy expenditure per square meter of residences, hospitals, and hotels. With this “final” data it calculates how much of this energy is transformed into GHG emissions”. Some cities such as Hartford (CT) and Houston (TX) used EIE data to establish climate action plans.

City example

The city of Nashville (TN), GCoM member since 2015, has significant experience in collecting and reporting emissions data. This process is crucial for the city to achieve its emissions’ reduction target. Nashville has a very well-established process for GHG inventories: “The Mayor’s Office sends emails, after that it’s about two months to gather data from utilities, departments, and planning groups. The Assistant Director leans in to get data in time, and a team for the Community Inventory and a team for the City Inventory come together to total the data. After the whole process, all the data will be available”, concluded Michelle Hamman, Research & Special Projects Manager of Nashville.

Nashville has an 80% emissions reduction goal by 2050 for the municipality and the community. This is seen in “Sustainability Advisory Committee Report 2021” which has 294 individual strategies on 6 topics: Energy, Green Buildings, Mobility, Natural Resources, Waste Reduction, and Adaptation.

Upcoming Webinar

The next session in the series will address how to identify and prioritize climate adaptation actions in your city or local government.


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