Green Cloud Computing

It is well known that the relocation of services to the cloud makes IT life easier, because mobile working saves journeys. But the data center also need energy. Server and storage must be produced and disposed of again after a few years of use. In the end, isn’t remote operation much more resource-intensive than traditional on-site work? To do the math, the Federal Environment Agency has developed the Green Cloud Computing method (GCC method).

This is behind the green cloud computing methodology

The GCC methodology calculates cost indicators for cloud services. The environmental expenditure for the production of information technology and the operation of data centers is recorded in four impact categories:

• • • Raw material expenditure (Abiotic Depletion Potential, ADP): Use of minerals and fossil raw materials in kilograms of antimony equivalents per year [kg Sb.eq./a]
    • Greenhouse gas emissions (Global Warming Potential, GWP): Effect on global warming in kilograms of carbon dioxide equivalents per year [kg CO2.eq./a]
    • Cumulative Energy Demand (CED): Consumption of energetic resources in megajoules per year [MJ / a]
    • Water Usage: Directly consumed water in cubic meters per year [m³ / a]

The environmental expenditure is compared with the respective benefit. Units of benefit are, for example, workplaces per year for a VDI environment, hours per year for a video conference system or terabytes per year for a storage solution. Usually several services run in a data center. The key figures are broken down to specific cloud services – such as video conferencing apps or virtual desktops – by giving each service a percentage of the environmental impact.

The cost figures indicate how efficiently and thus environmentally friendly the service is provided. “GCC = effort / benefit” always applies here. The Federal Environment Agency calculates four key figures per cloud service:

• • • In GCC ADP: raw material consumption in kilograms per service unit
    • The GCC GWP: CO2 footprint in kilograms of CO2 per service unit
    • GCC CED: Energy consumption in megajoules per service unit
    • GCC Water: water consumption in cubic meters per service unit

So far, the newly developed cost indicators have only been calculated for a few exemplary cases. That is, at this point in time they cannot be generalized. Nevertheless, they are already suitable for comparing similar cloud services with one another. To make the numbers more tangible, they can be compared with other carbon footprints such as “one kilometer per car journey”.

Video conference as a calculation example

How many travel kilometers do you have to save so that a video conference is “greener” than a meeting? For an exact statement, the GCC key figures would have to be determined for the specific service provider. The Federal Environment Agency determined the GCC GWP (CO2 footprint) indicator for a Jitsi provider and came to a surprising result.

The emissions in the data center and those of the participants in the home office must be considered separately. The load on the server was determined from log files of the Jitsi Video bridge in the data center. Unfortunately, it had to be estimated from then on, because the Jitsi operator rents his servers from a hosting provider who did not disclose any data on energy consumption.

The benefit of the service should be measured in participant hours. To do this, you form the product of the number of participants and the length of time that each participant spends in a video conference. In this case, the observation period was one week, so there was a unit of participant * h / where for the participant hours.

The courses of (measured) CPU utilization and (generously estimated) power consumption of all servers followed the number of conference participants almost synchronously. In this respect there is a connection between the number of users and energy consumption. From all the power consumed by the server, storage, network and infrastructure, the integration over time results in a weekly energy consumption for the cloud service. The weekly effort and benefit can now be divided.

So much for the usage phase. For the calculation of a GCC key figure from effort and benefit, the effort to create the data center is still missing; here, of course, the literature was used. In the end, greenhouse gas emissions from attending an hour video conference resulted in 2.27 grams of CO2 equivalents. This figure is made up of 0.34 grams (15%) for the manufacture of the server and 1.93 grams (85%) for the usage phase in the data center.

That’s all? No, the CO2 footprints of the transmission network and home networking of the end devices are still missing.

The amount of data transferred per participant for an hour of video conference was measured at an average of 612 megabytes per hour and participant. An energy model for telecommunications networks resulted in a power consumption of 1.92 watts for a VDSL internet connection at the technology level from 2017. Together with the emission factor of the German electricity mix for 2018 of 0.468 kilograms of CO2 equivalents per kilowatt hour, the Federal Environment Agency calculated the CO2 footprint of the transmission network for the participant hour in the network at 0.55 g CO2 eq./h.

It becomes more complicated with the devices in the home office, because they are used for different lengths of time and intensively. In order to obtain hourly values ​​for the manufacturing effort, the one-time manufacturing effort of the respective devices must be divided by the effective usage time in hours per device.

In the calculation example, three fictitious offices were compared: from the laptop at the kitchen table to the home office with desktop PC to the office with a large video monitor. The first figure shows the carbon footprints of the video conference in the three scenarios. Participation with a laptop is associated with 55 grams of CO2 equivalents per hour. With desktop PC and monitor it is already 90 grams.

I’m sorry, what? The key figure for the data center was only 2.27 grams per hour and participant. Correctly calculated! The greenhouse gas emissions for a standard office with a screen are almost 40 times higher than the proportionate emissions in the data center. Network and cloud service providers only play a subordinate role. The energy-saving equipment in the office determines how environmentally friendly we work.

When is the journey worthwhile?

The question remains of when to go to the meeting or when to attend from home. Can the travel time be used sensibly, what does the ticket cost, how does the conversation time relate to the travel time, or does the journey home collide with leisure plans.

The Federal Environment Agency uses average figures to calculate greenhouse gas emissions from passenger transport. With an average occupancy of the vehicles, the following CO2 equivalents per person-kilometer (pkm) can be assumed:

• • • Passenger car: 143 g CO2 eq./Pkm
    • City bus: 80 g CO2 eq./Pkm
    • Local rail transport: 55 g CO2 eq./Pkm
    • Long-distance train: 29 g CO2 eq./Pkm

If you put the greenhouse gas emissions of the video conference in relation to those of the means of transport, you get the distance that could theoretically be covered to meet in one place instead. If the emissions for the trip to and from the office are lower, the physical meeting is more climate-friendly. Otherwise, you can stay at home with a clear conscience.

The second figure shows the CO2 emissions of the three fictitious offices converted into passenger kilometers using different modes of transport. If a laptop is used, an hour of video conference can alternatively be covered between 0.26 person kilometers by car and one person kilometer by long-distance train.

When traveling by subway, the meeting place must be more than 0.69 kilometers away for an alternative participation with the laptop, so that the video conference is more environmentally friendly.

When participating with a desktop PC, the meeting place must be more than 1.12 kilometers away. The same applies to the other means of transport, although the long-distance train variant is ruled out due to the short distances involved.

In summary: go to the meeting on foot! If it is too far away for that, video conferencing is more climate-friendly.

Use of the key figures

The sample calculation comes from an exemplary application of the newly developed GCC methodology. It is intended to show that the methodology is well suited to identifying environmental impacts for individual cloud services.

In the future, the GCC methodology can be used for an environmental product declaration or energy consumption labeling for cloud services. It is obvious that particularly efficient services should be awarded an environmental label such as the “Blue Angel”. In addition, it can be used as a tool to optimize the individual sub-areas of a data center.

You can find all sources and backgrounds in the publication “ Green Cloud Computing – Life-cycle-based data collection on the environmental impact of cloud computing ” from the Federal Environment Agency.