Recent studies have estimated that television and related equipment account for 1.8% of global greenhouse gas (GHG) emissions and Information and Communication Technology is responsible for 2% of global GHG emissions. Both these sectors are forecast to grow as the developing world increases its uptake of technology.

This study estimates the carbon footprint of two different ways of watching television: using broadcast digital terrestrial television (DTT) and video-on-demand (VOD) over the Internet. It compares the two distribution methods and the corresponding consumer equipment. It uses the principles of life cycle assessment (LCA) to derive the carbon footprints using a bottom-up analysis of the system applied to the BBC’s television services. This was the only environmental impact considered and was mainly from electricity use. Equipment manufacturing was not included.

The main results showed that broadcast DTT has a smaller carbon footprint per viewer-hour than VOD for average sized audiences, but not with small audiences or for homes using an aerial amplifier. The largest environmental impact from watching television is from the consumer equipment. This is 76% for DTT; 78% and 37% for VOD using desktop and laptop computers respectively. The trend for larger screens could increase this although there is a parallel increase in viewing on small mobile devices. Programme-making contributes 12% to 35%.

Results were sensitive to the viewer numbers per display. Doubling the number of viewers per display reduces the carbon footprint by 44% for digital terrestrial television. For VOD, there was large uncertainty in the energy consumption data for the content delivery network and the Internet. However, this does not affect the main outcomes.

A future question is whether digital video recorders automatically recording the most popular programmes when they are broadcast, so that a viewer can watch them ‘on-demand’, would use less energy than video-on-demand over the Internet.

This document is partially based on work published in: Chandaria, Jigna (2010). A comparison of the carbon footprint of digital terrestrial television with video-on-demand, Masters thesis. Cranfield University. Cranfield.