In Carbon Title, c.scale provides embodied carbon estimates for both new and existing buildings. Methods for accounting for embodied carbon in new construction are increasingly well-established. For existing buildings, emissions from materials and construction are typically excluded. While this is technically correct, this method of accounting for emissions from existing buildings has had unforeseen consequences. For instance, the first purchaser of built-to-suit office spaces is not given responsibility for the emissions from the building's construction, as these emissions are assigned to the initial developer. This does not help us collectively reach our climate goals and makes it too easy to “pass the buck” on to other parties. 

To rectify this, we draw from a principle of accounting and depreciate the embodied carbon over time. We do this by taking the embodied emissions typically assigned to the first year of construction (A1-A5 emissions) and linearly depreciate them over 60 years. The assumption of a 60 year building life (the 'assumed building life') is chosen to align with relevant standards (LEED, RICS, a forthcoming ASHRAE standard, etc.). For example, when Carbon Title estimates a building older than 60 years, first year emissions are zero'ed out. When that building is 30 years old, first year emissions are 50% of what it would take to build the building anew.

Depreciating first year emissions rewards the reuse of older buildings, and ensures that building-related emissions don't disappear when an asset changes hands. By preventing these emissions from being disappeared from carbon balance sheets, c.scale and Carbon Title's depreciation mechanism provides necessary accountability for scope 3 emissions.

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