How can engineers make IT more sustainable? Part 2: How, why and what to measure

How can engineers make IT more sustainable? Part 2: How, why and what to measure Build • James Martin • 14/06/23 • 8 min read

The digital sector generates 4% of global greenhouse emissions . Data centers and hardware are the main contributors to that impact. But those machines — not to mention all software, websites, apps and more — run on code written by developers. This means their work’s impact is far from negligible. So how can engineers, and indeed anyone shaping tech today, reduce that impact?

In part 1 , we laid the foundations for a greener approach to IT, by explaining how data centers/cloud providers, hardware and software all need to be taken into consideration. In this chapter, we’ll look precisely at how their respective impacts can be measured. Because, as the saying goes, you can’t improve what you can’t measure! So let’s dive in…

The basics: Scopes 1-3

Scopes 1, 2, & 3 explained. Visual: Plan A

Any and all organizations looking to measure their greenhouse gas (GHG) emissions — and as of this year, impact reporting is obligatory for all European companies over 500 employees — must do so across three different domains, called “scopes”:

Scope 1 : Direct emissions from sources such as offices, company cars and so on.

Scope 2 : Indirect emissions from the purchase of resources such as the electricity required to run a company’s facilities

Scope 3 : The emissions an organization is indirectly responsible for, both upstream and downstream. This can include employees’ commutes to the office, and even the emissions consumers generate from using that company’s products.

As such, scope 3 is the most far-reaching, and therefore by far the most difficult scope to measure.

Naturally, different stages of the digital value chain have different impacts on each scope. On one end, for example, data centers can have a high scope 2 impact, as their GHG emissions linked to energy consumption can be considerable; on the other end of the scale, hardware’s impact can go right to scope 3.

A telecom operator, for example, could be held responsible for the GHG emissions linked to the manufacturing and usage of the telephones it sells to its clients… even though it didn’t make those devices itself. Impacts can also be far-reaching geographically speaking: sticking with the telephone example, Apple’s impact runs from China, where iPhones are made, to both its offices and its consumers in the US and beyond.

So, what are the best ways to measure impact across the entire digital value chain?

How green is your cloud provider?

The first place to research your cloud service provider (CSP)’s GHG impact is… with the CSP itself! All cloud providers should have some kind of impact report, which should tell you:

PUE , or Power Usage Effectiveness: how much energy a CSP’s data centers use, as a ratio of the energy used coming into a facility, and that used by its IT equipment. The global average is 1.57, but the closer it gets to 1, the better. Scaleway ’s average is 1.4, and its minimum 1.15. All CSPs have to provide this figure publicly

WUE , or Water Usage Effectiveness: how much water a CSP’s data centers use, as a ratio of the energy consumption. Scaleway declares the WUE of all of its French data centers. However, CSPs are not legally bound to declare this figure, so some do, some don’t. Scaleway’s average, of 0.21, is close to that of Meta (0.26) . Users should be particularly wary of CSPs who don’t declare their WUE, as this may mean they’re using high quantities of water to cool their data centers, and hence lower their PUE…

Energy mix : does your cloud provider use only renewable energy? It can, and if it does, it should say so. Similarly, is it paying attention to when and where electricity is the cleanest possible? For example, electricity in France comes mainly from nuclear and hydroelectric sources ( source ), so its carbon footprint is low compared with the USA, where 79% of energy comes from fossil fuels. Carbon intensity also varies depending on the time of day, so CSPs should run their biggest workloads when this intensity is lowest

CUE , or Carbon Usage Efficiency, is the amount of GHGs (expressed in kg of CO2) emitted by data center activities, divided by the amount of energy used by a datacenter’s IT equipment, in kWh. Scaleway’s CUE is 0.075 kgCO2e/kWh (market-based) or 0.142 (location-based). And on that topic:

Market-based emissions data is less accurate, as it’s based on emissions from electricity from sources companies have specifically chosen;

Location-based emissions data , as recommended by the industry standard GHG Protocol , is based on the carbon intensity of data centers’ local energy grids.

Other elements that can help you evaluate your CSP’s green credentials are to what extent it reuses its hardware , and/or works to prolong its lifespan; and whether it offers “green bills”, or other similar calculators, which quantify your cloud activity’s GHG emissions impact.

Look out for specific tools, like AWS Suscanner , “an open source tool that helps you create a more sustainable infrastructure on AWS”, or OVHCloud’s “carbon calculator”, a tool currently in development, which should do what it says on the box :)

Beyond the providers themselves, a number of other tools exist to evaluate CSPs’ impact on the planet. Cloud Carbon Footprint is a highly-respected free open source tool, designed to work with the biggest CSPs and more, which “provides visibility and tooling to measure, monitor and reduce your cloud carbon emissions.”

There’s also Scaphandre , another open source tool, which measures the energy consumption of specific pieces of hardware . Although it’s only in the early stages of development right now, and only works with RAPL , Intel’s protocol for power consumption, it’s a good place to start (measuring the energy consumption of servers in a data center, for example).

Other good starting points are Boavizsta , the French tech collective specialized in measuring a wide range of hardware’s energy consumption and GHG emissions, which is currently developing a stronger focus on CSPs in particular. You can check out their cloud data to date here . It’s also worth taking a look at the cloud sustainability tips of the Green Software Foundation (or “patterns for cloud”), which range from the obvious ( choose the cloud region closest to your users ) to the less evident ( scale down Kubernetes applications when not in use ).

Hardware: measuring…