How do you measure the cloud's environmental impact?

How green is the cloud? Reading these days, you’d think it was the next big green thing. In recent weeks, for example, we’ve covered companies bringing products to the cloud, research findings on how the cloud is a “game changer” for energy managers, cloud-based tools for designers, even ethical concerns related to cloud computing.

As my colleague Matthew Wheeland noted recently: “Everyone is talking about cloud computing as the future of IT, or the future of business, or the future of commerce, or all of the above.”

How green is it? Conventional wisdom is that cloud computing — the delivery of computing as a service rather than a product, in which computers access shared resources, software, and information, instead of each computer having its own — is a highly eco-efficient medium. In addition to dramatically reducing hardware and software, the cloud maximizes the utilization of all computing resources, at least in theory.

But calculating the cloud’s environmental benefits has been an elusive calculation, until now. — whose software-as-a-service business makes it one of the pioneers of cloud computing — recently proffered a metric for measuring the cloud’s environmental performance.

“We’re proposing carbon per transaction as the cloud performance metric that can best guide customer choice as the cloud becomes the dominant IT model,” Sue Amar, Sustainability Officer at, wrote recently on the company’s blog.

Amar explained the difficulty of comparing the environmental impact of different technologies. “For example, in the enterprise software space alone, technology can be delivered on-premise (single tenant architecture), through a private cloud (virtualized single tenant architecture) or via multi-tenant cloud computing like”

Last year, the company commissioned a white paper from WSP Environment & Energy (download – pdf) “to compare the energy use and carbon footprint of its cloud platform and services against equivalent on-premises and virtualized data center deployments.” The study determined that Salesforce’s multi-tenant model was 95% less carbon-intensive than on-premise software, with 64% less CO2 footprint than even the latest “private cloud” installations. Wrote WSP:

Dedicated infrastructure associated with on-premises deployments typically operate at very low utilization levels and do not benefit from the key features of public cloud computing; multi-tenancy and elastic provisioning which offer scalability (both up and down) and higher utilization rates. While a private cloud does benefit from elastic provisioning and higher utilization rates, it is clear that multi-tenancy is a critical driver of carbon efficiency.

Next page: Comparing carbon emissions per transaction

Photo of businessman standing alone at the field by Helder Almeida via Shutterstock.