In order to understand the electricity use of Internet services, it is important to have accurate estimates for the average electricity intensity of transmitting data through the Internet (measured as kilowatt-hours per gigabyte [kWh/GB]). This study identifies representative estimates for the average electricity intensity of fixed-line Internet transmission networks over time and suggests criteria for making accurate estimates in the future. Differences in system boundary, assumptions used, and year to which the data apply significantly affect such estimates. Surprisingly, methodology used is not a major source of error, as has been suggested in the past. This article derives criteria to identify accurate estimates over time and provides a new estimate of 0.06 kWh/GB for 2015. By retroactively applying our criteria to existing studies, we were able to determine that the electricity intensity of data transmission (core and fixed-line access networks) has decreased by half approximately every 2 years since 2000 (for developed countries), a rate of change comparable to that found in the efficiency of computing more generally.
There is increasing concern over the climate change impact of games consoles. There is, however, little research on the life cycle carbon impact of consoles and existing research (the majority of which is focused on usage) is outdated. This study uses life cycle assessment (LCA) methodology to compare the climate change impact of different console-based gaming methods (i.e. games played from a disc, a down-loaded file, or streamed from the cloud).
Console usage and Internet usage were identified as life cycle stages where data were unknown or uncertain. Two studies to improve the understanding of these areas were undertaken in this research and used to complete a cradle-to-grave carbon footprint study of gaming (compared using a functional unit of carbon equivalent emissions per hour of gameplay).
Results estimated that, for average cases, download is the lowest carbon method of gaming at 0.047 kgCO2e/h, followed by disc at 0.055 kgCO2e/h. Cloud gaming has higher estimated carbon emissions at 0.149 kgCO2e/h, largely due to the additional energy consumed during use in the Internet, gaming servers, and home router equip-ment. These findings only represent average cases and the size of game files and length of gameplay time were found to be key variables significantly impacting the results. For example, for games played for under 8 hours, cloud gaming was found to have lower carbon emissions than downloads (up to 24 hours when compared to disc).
In order to analyse these results, a new method for identifying which gaming method has the lowest carbon emissions with variation in both file size and gameplay time was developed. This has allowed for the identification of the thresholds in which different gaming methods have lowest carbon emissions, for any given range of input variables. The carbon emissions of gaming are highly dependent on consumer behav-iour (which game method is used, how long games are played for, and the type and size of those games) and therefore LCA based on average assumptions for these variables has limited application.