Green Hosting: A Sustainability Comparison

In discussions about sustainability and climate protection, digital solutions are often perceived as "green alternatives." However, the internet and software applications also cause massive CO₂ emissions. Hosting – the operation of websites, applications, and services in data centers – plays a central role in this.

When we visit a website like peerigon.com, energy is consumed in many places – and this causes CO₂ emissions. This happens, for example, on the end device we use, during the transport of data over the internet, and in the data centers that provide the website. All of this plays a role in the climate footprint of the internet.

In this blog post, we focus on the topic of hosting. We look at the impact of hosting on the CO₂ footprint and provide tips on how your application can be hosted as environmentally friendly as possible. We will cover additional topics in subsequent blog posts.

Why? Because hosting is an important lever for sustainable software. Here, companies can make a significant contribution to reducing their CO₂ footprint by choosing providers that use 100% renewable energy.

Green hosting essentially means that a provider uses predominantly or completely renewable energy. At the same time, a data center can take further measures to reduce or compensate for CO₂.

Renewable energy includes sources that naturally regenerate and do not consume finite resources. These include energy from sun, wind, water, and geothermal heat.

⚛️ Nuclear energy is often not considered renewable energy due to the finite nature of uranium fuel and existing safety risks, although it is low in CO₂. Organizations like the Green Web Foundation exclude nuclear power, while it is considered "green" under certain conditions in the EU taxonomy.

In practice, many data centers combine energy efficiency, renewables, and compensation to market their energy mix as "green." It is important to question the details.

• CO₂-reduced: Aims for lowest possible CO₂ emissions, for example through efficient cooling, modern hardware, and a high proportion of renewables. However, a certain fossil remainder can remain in the mix.
• CO₂-compensated: Electricity can still be fossil, but is calculated to "zero" through certificates or investments in climate protection projects (e.g., reforestation, wind farms).
• CO₂-free: Refers to electricity that causes hardly any CO₂ emissions during operation, e.g., wind, solar, or hydropower – but often also nuclear power (controversial because it is not renewable).
• Renewable: 100% regenerative electricity (wind, solar, hydropower, geothermal, biomass) – no nuclear energy.

The following steps will help you determine whether your website or application is hosted in a green data center:

Many hosting providers communicate their sustainability measures transparently. Providers like Hetzner or Greenhost are examples of companies that openly explain how they use renewable energy and operate their data centers efficiently. Look on your provider's website for keywords like "100% renewable energy," "green hosting," or "CO₂-neutral operation." If you can't find any information, ask the support team directly.

Screenshots: Green Web Directory

• With the help of the Green Web Check from the Green Web Foundation, you can specifically check whether your website is hosted in a "green data center."
• The Green Web Dataset contains a machine-readable list of domains, their associated hosters, and an assessment of whether they are "green." The corresponding API is also practical.
• The Green Web Directory is aimed more at humans than machines and provides a list of hosters that have been classified as "green." Conveniently including evidence ("published evidence").
• EcoGrader and Website Carbon also provide useful insights as they show whether the hosting is sustainable. They also provide information about the energy consumption of your website and the resulting CO₂ footprint.

✉️ If your website is not rated as green, the Green Web Foundation has kindly prepared templates for inquiring with your hoster.

Certificates such as ISO 14001 or the Green Web Foundation label are awarded according to clear criteria that demonstrate environmental management or the use of renewable energy. These certificates provide a reliable basis for evaluating providers.

ISO 14001 A hosting provider certified according to ISO 14001 proves that it continuously identifies, documents, and tries to reduce its environmental impacts with concrete measures.

Green Web Foundation Label The Green Web Foundation label is awarded to hosting providers that demonstrably rely on renewable energy or obtain climate-friendly electricity to a high degree.

Consumers and companies can quickly recognize whether a provider is "green", i.e., whether it uses a significant amount of green electricity instead of fossil or nuclear energy sources.

When evaluating "green hosting," you will encounter different types of energy certificates:

• PPAs (Power Purchase Agreements): Direct electricity purchase agreements with renewable energy producers - the most reliable form as they actually contribute to the expansion of renewable energy
• RECs (Renewable Energy Certificates): Proof of renewable energy generation that can be purchased retrospectively
• GoOs (Guarantees of Origin): The European equivalent to RECs, similar as a balance sheet instrument

💡 Important to know: While PPAs establish a real physical connection to renewable energy sources, RECs and GoOs primarily serve as compensation instruments. They merely prove that renewable energy was generated somewhere, but do not necessarily mean that green electricity is physically flowing at the provider. This type of balance sheet compensation is common but should be viewed critically.

❔ What about green electricity tariffs? Certified green electricity tariffs are also usually a balance sheet allocation – so you don't necessarily get physically green electricity from the socket. Instead, the provider guarantees that the same amount of electricity from renewable sources is fed into the grid and verified by guarantees of origin. The quality of the tariff is decisive: Offers with recognized seals such as ok-power or the Green Electricity Label additionally guarantee that part of the electricity price is invested in new plants.

Reading tip: An interesting article on the topic can be found on the Mightybytes blog: Web Hosting and Renewable Energy

The location of your data center has a decisive influence on the CO₂ balance: Apart from the electricity that is directly produced and used by the data center operator, such as through PV on the roof of the data center, the required electricity comes from the local power grid and thus corresponds to the local electricity mix.

Screenshot of electricitymaps showing Europe

Especially if you run your applications with one of the major cloud providers, you can significantly reduce your CO₂ footprint by choosing the right region.

The easiest way to improve the CO₂ balance: Move your services to regions that are predominantly powered by renewable energy.

With tools like Electricity Maps, you can compare the share of renewable energy sources in different regions and make an informed decision.

Based on the real-time data from Electricity Maps, workloads that run in the background – such as data aggregation – can also be specifically shifted temporally or spatially to regions where the power grid is particularly "green" at the moment (carbon-aware scheduling).

Example: If your application/website is mainly used in Germany, it would be nonsensical to choose servers in New Zealand just because the electricity there is particularly green. The large distance between the server and users creates immense latency, which is also reflected in higher emissions that are generated on the long "transport route." Cloud providers operate data centers in many regions. Usually, there is a "greener" region without major compromises in price/latency.

Comparison of CO₂ intensity in different Google Cloud regions

Users will hardly notice whether the application is running in Warsaw or Paris. But it makes a decisive difference for CO₂ emissions. The Paris example is particularly interesting because France relies heavily on nuclear power. If you want to rely as much as possible on renewable energy, you should therefore host in Zurich, where more hydropower is used.

The PUE value provides information about the energy efficiency of a data center. It represents the ratio between the total energy consumption (including cooling, lighting, etc.) and the consumption of IT systems (servers, storage, network devices). Why is PUE important? A low PUE (e.g., 1.1-1.3) signals that a data center is operated particularly efficiently because less energy is wasted on "overhead." Providers like Google or AWS often provide average values for the PUE of their data centers (e.g., 1.1 for Google). Make sure that these values are published transparently.

The three largest cloud providers are significantly below this:

Those who can do without the big hyperscalers (Amazon, Google, Microsoft) and want to avoid compensation as much as possible will find several hosting providers in Europe that focus on renewable energy:

• Scandinavia 🇳🇴: Iceland, Norway, Sweden (high proportion of hydropower, geothermal, wind) with providers like EVRY (Norway), Greenqloud (Iceland) or Zone (Estonia)
• Switzerland 🇨🇭: Hydropower-driven data centers, e.g., Infomaniak
• Smaller Green Hosters 🌿: e.g., manitu, Greenhost etc.

There are almost always residual emissions because power grids rarely deliver CO₂-free (carbon-free) electricity around the clock. Therefore, these providers also sometimes use certificates to balance out the mix.

Finally, we want to address the question of the magnitude of Green Hosting's contribution to CO₂ reduction. This question can be answered with a classic "It depends" – because the effect depends largely on the application.

There are fundamentally two perspectives:

Page Weight Model (Frontend) – relevant for websites, content platforms, marketing pages:

• The CO₂ emissions per page view are calculated here
• The hosting share is typically 10–30%

Runtime Model (Backend) – relevant for APIs, microservices, streaming, ML inference:

• The continuous power consumption of applications over the year is considered.
• An API container with 1 vCPU / 2 GB RAM in continuous operation causes about 130 kWh/year, which corresponds to 50–80 kg CO₂ with an average electricity mix.
• The hosting share here is almost 100%, and can also be almost completely avoided through green hosting.

For our example calculation, we use the Page Weight Model. We want to address the Runtime Model in another blog post.

To calculate the CO₂ footprint of websites, we use the methodology of the Sustainable Web Design Model (SWDM), developed by Wholegrain Digital, Mightybytes, and the Green Web Foundation.

The SWDM takes into account various factors and distributes emissions across three main systems:

• Data centers (server): 22%
• Networks (internet): 24%
• End devices (computers, smartphones): 54%

The basic formula for the calculation is:

More specific calculations can take into account additional factors such as caching effects, green hosting, and the ratio between new and repeat visitors.

For our calculations, we use an emission factor of 0.8 g CO₂e per megabyte of data transferred. This value is based on the SWDM model and is also used by tools like websitecarbon.

To illustrate the range, we consider three different scenarios:

• Small blog website 📝: Private blog or small club site
• Medium-sized company website 🏢: Typical corporate presence with several sections
• Large e-commerce platform 🛒: Extensive online shop with many products

These example calculations show: The CO₂ footprint of digital offerings scales dramatically with visitor numbers and data volume. While small websites cause only minor absolute emissions, large platforms can generate CO₂ amounts in the order of several long-haul flights annually.

The good news: Whether small, medium, or large - the percentage savings potentials are similar. For large platforms, this means a saving of several dozen tonnes of CO₂ per year.

Switching to Green Hosting is one of the most effective and at the same time easiest steps to implement in the field of sustainable digitization. Unlike extensive code optimizations or complete redesigns, the switch to a green hosting provider can often be completed within a few days - with an immediate effect on the CO₂ balance.

For decision-makers in companies, Green Hosting also offers a double advantage: The measure is both ecologically effective and easy to communicate. As our calculations show, the concrete savings can be presented in catchy comparisons and can be an important component in the sustainability strategy of companies.

Green Hosting is a central building block on the path to more sustainability on the internet. The increasing size of websites – from an average of 505 KB in 2014 to 2.31 MB in 2024 for mobile pages – reinforces the importance of energy-efficient and climate-friendly hosting solutions.

By switching to a provider that relies completely on renewable energy, the CO₂ footprint of a website or application can be significantly reduced – for complex applications, this can mean a saving of several tonnes of CO₂ per year.

In addition to choosing green energy sources, other factors play an important role:

• Location of the data center 🗺️: Prefer regions with a high proportion of renewable energy
• Energy efficiency ⚡ (PUE value): The lower, the better for the environment
• Certificates and labels 🏅: Look for reliable proof of green electricity and environmentally conscious management
• Energy origin 💡: PPAs offer a more direct connection to renewable energy than RECs or GoOs

In addition to Green Hosting, the following optimization levers can be used, which we will address in further blog posts:

• Reduce page weight 📉: Optimize images, JavaScript, and other resources
• Improve server utilization 🖥️: Use efficient technologies such as Serverless Computing
• Minimize client load 📱: Develop lean frontends

Green Hosting is thus a relatively easy-to-implement, but very effective lever to make digital products more sustainable – especially for larger and more complex web applications.

🤖 Statement about usage of AI in this article: This article was written by humans (thanks for the feedback Hannes, Leo, Julia, Lisa!), including the title, concepts, code samples. However we used AI for research and to enhance the style of writing.

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• Atomic Energy (Nuclear Energy): Although considered low in CO₂, it is not considered renewable because uranium is a finite resource and disposal and safety issues remain unresolved.
• Carbon-Aware Scheduling: Strategy where workloads are shifted temporally or spatially to regions with a high proportion of renewable energy or to times with particularly "green" electricity, in order to minimize CO₂ emissions.
• Carbon-aware SDKs / APIs: Developer tools that enable software behavior to be adapted to CO₂ intensity of the electricity mix in real time. Examples: WattTime API, Microsoft Emissions Impact Dashboard.
• CDN (Content Delivery Network): Global network that stores web content (e.g., images, videos) on servers close to users. It minimizes latency and data traffic, but often makes it difficult to clearly assign to a specific hosting region.
• CO₂-reduced (carbon-reduced): Energy mix with a high proportion of renewable energy (RE), but still contains a certain proportion of fossil energy sources.
• CO₂-free (carbon-free): Electricity or operation with minimal CO₂ emissions, although nuclear power is often classified as low in CO₂, but not considered renewable.
• Embodied Carbon: CO₂ emissions generated during the manufacturing, transport, and disposal of hardware (e.g., servers). Typically counts as Scope 3.
• Renewable Energy (RE): Energy forms that regenerate themselves, e.g., wind, solar, hydro, or geothermal energy. Nuclear power is not included.
• Green Software Carbon Intensity (SCI): Metric of the Green Software Foundation that measures the CO₂ intensity per functional software unit (e.g., g CO₂e per API call). SCI = Total Emissions / Functional Unit.
• Green Software Foundation (GSF): International community and NGO that develops standards, metrics, and open-source tools for green software.
• Green Web Foundation: Organization that evaluates hosting providers according to their sustainability and awards labels when providers demonstrably obtain a high proportion of renewable energy or implement climate-friendly measures.
• Guarantees of Origin (GoOs): European equivalent to RECs. They certify on balance that a certain amount of electricity comes from renewable sources - not necessarily physically arrived at the consumer.
• Hosting (Green Hosting): Operation of web services in data centers that are fully or predominantly powered by renewable energy. The CO₂ footprint can be drastically reduced as a result.
• Hyperscaler: Large cloud providers like Amazon Web Services (AWS), Microsoft Azure, or Google Cloud. They operate data centers in many regions and offer various sustainability options.
• ISO 14001: International environmental management standard that obliges companies (including data centers) to systematically reduce their environmental impact.
• Climate-neutral (compensated): Emissions are offset by compensation (e.g., certificates, reforestation). Also referred to as CO₂-neutral - often on balance.
• Load Shifting / Demand Shaping: Strategies to shift energy consumption into greener time windows (e.g., at night, with a lot of wind or solar power surplus).
• PPA (Power Purchase Agreement): Direct purchase agreement with a renewable energy producer - considered the most reliable form of sustainable energy supply with high additionality.
• PUE (Power Usage Effectiveness): Ratio between total energy consumption of a data center and the actual IT power requirement. A value <1.3 is considered efficient.
• RECs (Renewable Energy Certificates): Certificates for the generation of renewable energy that can be acquired on balance. Do not prove that physically green electricity flows.
• Runtime Footprint: Energy and CO₂ consumption of an application during its active runtime. Relevant measurement point for APIs, microservices, or ML inference.
• Scope 1, 2, 3 Emissions: Classification of the GHG Protocol:
  • Scope 1: direct emissions (e.g., emergency power generators),
  • Scope 2: purchased electricity,
  • Scope 3: all other indirect emissions (e.g., supply chains, hardware, use by customers).
• Page Weight: Amount of data transferred when loading a web page. Includes HTML, CSS, JavaScript, images, fonts, etc. Important lever for CO₂ reduction.
• Serverless / Function-as-a-Service (FaaS): Cloud architecture where resources are only provided when needed - reduces energy consumption through better utilization.
• Software Carbon Intensity (SCI): See Green Software Carbon Intensity.
• Time-based Carbon Intensity: CO₂ intensity of electricity varies over the course of the day. Basis for time-optimized (carbon-aware) planning of workloads.
• Certificates / Offsets: Financial mechanisms to compensate for emissions. Enable climate-neutral operations on balance, but do not replace avoidance or reduction.