Information and communication technologies are radically transforming modern lifestyles. They are redefining our concept of "space" by turning homes and coffee shops into workspaces. (This article was written in a coffee shop.) Instead of going to the theater, many people sit in the comfort of their homes and stream movies. Online purchasing of food, groceries and consumer products has transformed shopping. Personal interactions, from the casual to the intimate, are increasingly virtual instead of face to face.

How can we measure the impacts of these changes? Time diaries are one tool for quantifying lifestyles and trends. A time diary is a survey in which people list what they do and for how long, from waking up in the morning to going to bed at night.

Along with our colleague Roger Chen, we analyzed data from 2003-2012 from the American Time Use Survey, which is conducted annually by the U.S. Bureau of Labor Statistics, to gain insights into our digital lifestyle and its effect on national energy use.

Our recently published findings are surprising. Americans spent nearly eight more days at home in 2012 compared to 2003, and even when we allow for displaced energy consumption — such as the electricity required to run server farms — they consumed less energy. This is good news, but it also raises important concerns about making home energy use more efficient.

Read the full article about Americans saving energy by Ashok Sekar and Eric Williams at The Conversation.