May 2024 Emissions Model

Full details on the updates to our emissions model that go live on May 1. These updates increase accuracy, improve compliance with the SRI framework, and lay groundwork for the upcoming GARM standards.

Overview

At Scope3 we believe that openness and transparency are key to learning together and driving faster systemic decarbonization of the digital advertising ecosystem. As we move towards a model that is even more oriented around contributed data from ATPs and publishers, we want to make sure our model aligns to the datasets we can consume.

We also want to make sure our fundamental model can be aligned to other methodological standards / frameworks and give customers the choice in which framework they adopt.

The formulas for each piece of the emissions model, along with the important coefficients, are outlined here: https://methodology.scope3.com/calculations. The model that goes into effect May 1, 2024 leverages the methodology outlined in that document. This model will be used on both our v1 and v2 API endpoints.

That page is rather long, and so, here is a summary of the foundational changes between the current scope3 model and this new version.

Explore the new model

To easily see how the new model compares to current model, you can use our v2 /measure endpoint with the latest flag set to true. Or, you can login to scope3.com and look at the latest dataset in the property report page (seeing the latest dataset in the UI is limited to premium users).

Frameworks

Fundamentally, this methodological change sets us up to support multiple frameworks. Currently, the only available frameworks are scope3 and scope3-consumer-device. We are also planning support for additional frameworks as and when they become available to the industry. For instance, some of the initial work to support the SRI framework is already present in our methodology repo where we have begun documenting some of the core defaults/coefficients that SRI uses and how they compare with the Scope3 defined defaults.

Core Changes

When network is not specified, we now use a blended default network instead of assuming fixed/mobile

Previously we would assume that Tablet, TV, PC device types were using a fixed network when network was unspecified. We would assume Smartphone device types were using a mobile network when network was unspecified.

We now use the blended number using the default splits of percentage use of mobile network by country here: https://methodology.scope3.com/calculations#mobile-to-fixed-ratios-by-country

Including data transfer to ad selection supply partners

Previously, our ad selection model was only considering the server cost of the supply partners and was not counting the networking cost of the request from the consumer device to the supply partner server. Ad selection now includes the data transfer in the overall ad selection cost. Calculations can be found here: https://methodology.scope3.com/calculations#ad-selection-data-transfer

The breakdown of the overall ad selection between the platform cost and the data transfer cost is available in our v2 API. Our V1 API (deprecated), uses the new model but does not expose the breakdown between platform and data transfer.

Data Transfer Embodied Emissions

Previously we were not incorporating the embodied emissions of the networking devices in any of our data transfer calculations. Now, we are incorporating the emodied emissions. So, data transfer costs will be going up in the model. Equations can be found here: https://methodology.scope3.com/calculations#media-delivery-data-transfer

As an example, assuming

• a fixed network transmitting 100KB of media delivery per impression on a display property
• a carbon intensity of 753 gCO2e per kwh

Media Delivery Data Transfer Usage: 100 KB/imp * 0.03 kwh/GB * 753 gco2e/kwh / 1000 = 22.59 gco2pm (grams per 1000 impressions)

Media Delivery Data Transfer Embodied: 100KB/imp *. 0.00000443 grams / KB * 1000 = .443 gco2pm

So, in this example, including data transfer embodied emissions results in this portion of the emissions increasing by ~2%.

Including the ad server in ad selection platforms

Formerly, our ad selection graph only included programmatic sellers but did not include the publisher ad server. The publisher ad server is now included in the overall ad selection platform cost. This results in the overall ad selection emissions increasing slightly. For properties that rely on dozens (sometimes hundreds) of resellers, the inclusion of the publisher ad server has a negligible impact on the total ad selection platform cost.

Adjusted default bitrates for video and audio media

The new default transmission rates can be found at https://methodology.scope3.com/calculations#media-size