There's an important principle of economics popularized by Robert Heinlein and quoted by Milton Friedman known as TANSTaaFL, short for "There ain’t no such thing as a free lunch." It's as true today as it was in the taverns of New York in the 19th century where they fed you if you bought a drink. The cost may be direct (more expensive drinks) or something external (like treatment for alcoholism).

Even in our modern age of smartphones, TANSTaaFL still holds true. A new study (PDF) compared 21 android smartphone apps that follow the “freemium” model, where there is a free, advertiser-supported version and a paid premium ad-free version. According to the abstract:

Our study of 21 real world Android apps shows that the use of ads leads to mobile apps that consume significantly more network data, have increased energy consumption, and require repeated changes to ad related code.
price of free app graphic

A little ad is a big drain and a big pain. (Photo: Molly Zisk @USC)

It’s not like the apps are consuming a huge amount of power, but with the teeny batteries in phones it makes a big difference. The apps with ads use a median of 15 percent more energy and some as much as 33 percent. That’s a tiny amount of energy, only 50 joules, but it can mean a hit of as much as 1.7 hours of running time on the battery, requiring charging 33 percent more often. It also clogs the works, resulting in up to 56 percent more time that the CPU is cranking. 

This is also costing you real money. After calculating the average increase in network load feeding all the ads in each use (a tiny 243,671 bytes), and taking AT&T’s average cost per MB, the study “determined that each execution of the with-ads version could potentially cost end users $0.017 more in terms of network charges.” That adds up, and even if you have a flat data plan, you're paying for that somewhere. 

William Halfond of USC, one of the co-authors of the study, tells that app designers and vendors should think about this energy use.

In absolute terms, this is very low, but in the crowded and competitive world of apps, it’s a huge difference,” Halfond said. “It can make the difference between your app getting downloaded or going unnoticed.”
As more and more of our computing happens on our phones, there will be more pressure on our batteries and our networks. It was probably too much to hope for that the crapware that clogged our computers wouldn’t follow us to our phones, but it has. And it matters. As Halfond concludes, "Apps are the future of software. The thought that we’ll all be continuing to consume software on desktops is passé.”

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Lloyd Alter ( @lloydalter ) writes about smart (and dumb) tech with a side of design and a dash of boomer angst.

Truth in advertising: Your ad-supported 'free' apps are a huge hit on battery life and performance
Ad supported "free" ads have a real cost in performance and battery life.