Since the first online ad in 1994, advertising has grown into a vast ecosystem delivering billions of ads daily. Advertisements are everywhere on the Web: search engines promote results, most websites display ads, some require users to accept ads as a condition for access, video streaming services fund their infrastructure through an increasing volume of ads, and much of the gaming industry has adopted ad-based revenue models. In exchange for free access to a wide range of content, web users sacrifice their privacy and pay with personal data to enable targeted marketing.
We argue that the ad ecosystem imposes an additional, overlooked, cost on web users: energy consumption. Indeed, every ad rendered on a screen requires CPU cycles, GPU calculations, RAM and bandwidth usage, all at the users' expense.
In our paper, we quantify that cost. We design a robust methodology aimed at realistically modeling user behavior and monitoring CPU activity. Through measurements of 724,994 website visits across four real consumer devices, we study the energy implications of blocking ads and consenting to tracking.
We visit a set of relevant, high-traffic websites without blocking ads and tracking. We measure the energy consumption induced by these visits using PowerAPI.
We reproduce the previous visits (same websites, same behavior) measuring the energy consumption again, this time blocking ads and tracking. For example, we leverage uBlock Origin as a browser extension, or AdGuard Home as a blocking DNS server.
We compare the energy consumption from the baseline crawl with the crawl using an ad-blocker, website-to-website (e.g., google.com vs google.com).
Despite consuming CPU cycles for their own filtering, ad blockers generally reduce energy consumption for the end-user. The legacy uBlock Origin browser extension offers a median -9.62% saving when accepting functional cookies.
Google's forced migration from Manifest V2 → V3 (uBlock Origin → uBlock Origin Lite) reduces the energy benefits of blocking ads and tracking.
Energy consumption actually increases on specific websites due to behavior changes when ads and tracking are blocked.
Consenting to tracking via cookie banners increases median energy consumption by 2.57% compared to accepting only cookies required for websites to work. Accepting all cookies triggers a median 8.5 extra requests, 2 of which are detected as advertising and tracking.
This is a conservative lower-bound: some sites track users regardless of consent, and tracking scripts often begin loading before any banner interaction takes place.
Websites relying on ads for their economic model (e.g., online news) show the biggest energy consumption benefits when blocking ads and tracking.
| Category | Ad Request Ratio | Median Energy Reduction |
|---|---|---|
| News | 41.94% | -17.67% |
| Shopping | 26.05% | -10.52% |
| Business / Economy | 30.11% | -7.53% |
| Entertainment | 35.05% | -6.77% |
| Technology / Internet | 26.97% | -4.91% |
| Government / Legal | 17.75% | -2.66% |
For more results and discussions, see the full paper.