When is the Cloud more (or less) sustainable?

One of the grand delusions of geeks is the belief that “the Internet” is always advancing, and everything is getting faster, cheaper, better over time. So, it isn’t a surprise when the current move to “cloud” services – shifting computing to local PCs is touted as a “greener” solution than the old days. The “cloud” certainly sounds romantic – a heavenly, ethereal service in the higher beyond replacing the dirty sweatshop of one’s local CPU.

In practice, the sort of techno-religion which makes it difficult for many to understand, much less accept sustainability issues with respect to the Internet sees new services like cloud computing as one-dimensional goods. In all the discussions of the coming era of cloud computing, it is often assumed as automatically better. But “cloud” computing is just a vaguely spiritual name for a huge collection of always-on networked servers, routers, wires, microwave towers, and other Internet gear which may or may not be more sustainable than working locally. Sure, if the cloud servers reduce the amount of idle CPU churning, it is more sustainable. If cloud computing enables more magical thinking about the Internet as a “weightless” medium and the creation and use of services that increase the energy grab of the Internet, it is less sustainable.

These issues can, and should be decided with numbers. Assuming that the Internet is greener because it is new, and that the cloud is green because it is “new-new” Internet is a bad plan. Likewise, assuming that one’s personal contribution to Internet pollution is too small to notice, simply because the Internet seems so big will result in wasteful virtual consumption. Since we are all going to use these services, its important that we make sure they are designed in a sustainable fashion.

So, it is nice to see that recent study actually looked at the cloud’s efficiency, in particular for online web apps which are destined to replace the local copies of software installed on your PC. A recent study cited on PubMed.gov (?), by D. R. Williams and Y. Yang,  entitled Impact of office productivity cloud computing on energy consumption and greenhouse gas emissions looks at the footprint of these new era web apps. The authors, from the Technologies for Sustainable Built Environments (TSBE) Centre,  examined the energy footprint of the online version of Microsoft’s Office (365), versus that of traditionally installed Office software.

Even better, the study uses what appears to be a real LCA model, incorporating energy consumption at the data center, network, and end user. Multiple Office products were examined under different use contexts in order to give a balanced view. The results are summed up in this quote:

The power consumption of the cloud based Outlook (8%) and Excel (17%) was lower than their traditional counterparts. However, the power consumption of the cloud version of Word was 17% higher than its traditional equivalent. A third mixed access method was also measured for Word which emitted 5% more GHG than the traditional version.

Now, why was the cloud higher in some cases? The reason appears to be updates. If you are using an application that you can edit for a while without saving, the cloud wins. So, for email (where the time spent locally composing a message is short relative to sending) or spreadsheets (where you can apparently work in cloud Excel for a long time without uploading). In contrast, Word, where frequently edits are applied and posted to the cloud, had a biggere energy footprint when run through the cloud.

It’s worth noting that Microsoft apparently provided support and data for the project. The company is showing interest in reducing energy consumption, witness their marketing of IE 9 and IE 10 browsers as more efficient than Chrome or Firefox.

An even more detailed study on cloud services provides more ammo.  In a study by Jayant Baliga et.al. in IEEE, entitled Green Cloud Computing: Balancing Energy in Processing, Storage, and Transport”  cloud computng is shown to frequent increase, rather than reduce energy use. The culprit is transport, rather than storage or servers, which rapidly becomes the most energy-hungry component of the system as traffic increases.  Compared to a local laptop,

Comparing the power consumption of the laptop HDD and the storage service, it is clear that at low download rates, the storage service is more efficient, but this benefit vanishes if the number of regularly used files is larger, and if downloaded frequently.

However, the per-user savings for infrequently updated web apps are often only a few watts for standard use. So, running Word in the cloud might not be so bad. The big guns come out in so-called “rich media” streaming media (audio or video). Framerates providing an acceptable movie experience require lots of servers, with only a few individuals using each server, and in this case, the cloud becomes less efficient than a local copy of a movie on your PC. According to these authors,

Cloud software as a service is ideal for applications that require average frames rates lower than the equivalent of 0.1 screen refresh frames per second.

Remember that “framerates” are roughly equivalent to refreshing the screen in a non-video app. In regular editing this can happen many times in a minute. The authors conclude:

…under some circumstances, cloud computing can consume more energy than conventional computing where each user performs all computing on their own PC. Even with energy-saving techniques such as server virtualization and advanced cooling systems, cloud computing is not always the greenest computing technology.

In other words, if you are saving once a minute or less, the cloud service is likely the better choice. But if you’re doing edits requiring lots of communication with the cloud (online graphic design tools, cloud 3D GPU rendering systems come to mind) you are more of an energy hog than someone relying on their local computer. So, it is possible that online design tools like Edge will be problematic if they constantly upload and download cloud data to construct their user interfaces.

How does the cloud affect designers and developers? The theme of this blog is that “design is the problem,” and sustainable websites and online resources are a design, not an engineering problem. Design of certain kinds of cloud services will increase the carbon footprint of the Internet, while others will decrease it. Some rough guidelines might follow these suggestions:

1. Make sure as much user interaction can happen on the client-side

2. Avoid creating cloud services requiring constant animation, video, or user interaction

3. Push “state” to the browser, so that the app can make local intelligent decisions, and use the cloud at a low framerate.



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