Digital broadcasting platforms and global TV shipments
Digital terrestrial television (DTT) broadcasts have been growing, accounting for about 20% of the 1 billion DTV households worldwide in 2014 (Murray 2014). Of digital-broadcast recipient households (henceforth referred to as digital households), 36% are cable TV subscribers who may own an analog TV but use a digital cable box from the service provider (Murray 2014, Cheung et al. 2011). Internet protocol and satellite (i.e., direct-to-home or DTH) make up the remaining 44% of digital households. As a result of the growing penetration of DTV broadcasts, the number of analog-broadcast recipient households (henceforth referred to as analog households), including terrestrial and cable, has been rapidly decreasing, from approximately 860 million households (∼60% of TV households) in 2010 to approximately 500 million households (∼32% of TV households) in 2014. Among those, analog terrestrial households number about 317 million in 2014 (Murray 2014). Because many countries have yet to complete a digital switchover, the energy savings opportunities in the global DTV transition could be substantial. There are four main DTT standards: ATSC (Advanced Television Systems Committee, adopted by USA, Canada, South Korea, Mexico, and some Central American countries); DVB-T (Digital Video Broadcasting–Terrestrial, adopted by Australia, Europe, Africa); ISDB-T (Integrated Services Digital Broadcasting–Terrestrial, adopted by Japan, Brazil, and several Latin American countries); DMB-T (Digital Terrestrial Multimedia Broadcast–Terrestrial, adopted by China) (ITU 2013, Pizzi and Jones 2014). More technical details of the four DTT standards are out of the scope of this paper.
Prior to 2007, sales of TVs that had a built-in digital tuner capable of directly receiving digital signals were not significant. We roughly estimate that less than 100 million flat-panel TVs were shipped between 1998 and 2006; by contrast, about 90 million flat-panel TVs were shipped in the year 2007 alone (DisplaySearch 2010). The cumulative global flat-panel DTV (TVs assumed to be mostly with built-in digital tuner and decoder) shipments between 2007 and 2014 were estimated to be approximately 1.4 billion units (DisplaySearch 2010, 2011, 2013, 2014a, 2014b). Given the significant number of DTV sales since 2007 and a TV lifetime of 6 years based on recent country-specific surveys (DisplaySearch 2012a), we estimate that roughly 1.2 billion digital flat-panel TVs (i.e., all high-definition [HD] or higher-definition flat-panel TVs) were in use worldwide in 2014. When we compare (see Fig. 1) this estimate with the number of digital households in 2014 (∼1 billion) and account for digital household TV ownership rates (>1), we can reasonably conclude that very few households that currently receive analog signals have already upgraded to digital TVs. We used this approach to estimate the number because we could not find data that directly report the TV type in analog households.
Penetration of digital broadcasts by country
The DTV transition is expected to accelerate as many countries have already set deadlines for digital switchover before 2020. According to Murray (2014), DTV broadcasts overall were estimated to have reached two thirds (∼1 billion) of all TV households across 138 countries at the end of 2014. Top 10 countries (China, USA, India, Japan, Brazil, Germany, Russia, France, UK, and Italy) account for about 68% of the global digital households. The developed countries (USA, Japan, Germany, France, UK, and Italy) in the top 10 show high penetration rates of DTV households, in the range of 82 and 100%; other countries have less than 60% penetration. Although it is not surprising that China has the largest number of TV and DTV households, it is also estimated that about 240 million households in China, India, and Indonesia were still receiving analog TV signals in 2014, accounting for 48% of total analog households worldwide. In China and Indonesia, about 78 and 100% of analog TV households, respectively, are estimated to receive analog terrestrial signals. Nearly 90% of analog TV households in India are analog cable subscribers (Murray 2014). Countries in the Asia-Pacific region, including China, India, and Indonesia, represent approximately 60% of global analog terrestrial TV households Fig. 2.
Digital TV technologies and related energy consumption trends
The United States Environmental Protection Agency (US EPA) ENERGY STAR program defines a DTC as “a device that receives terrestrial (over-the-air) digital signals and converts them to an analog output suitable for analog TVs”. The definition does not include converters for satellite or cable digital signals or devices that perform multiple functions, e.g., DVD players with DTC capability (US EPA 2012). A set-top box (STB) can be defined as “an appliance for the reception, decoding, processing and local networking of digital broadcasting and related services” (MVV 2007). As recent TVs have integrated tuners and decoders to receive digital broadcast signals, consumers who have those TVs do not need a basic DTC, which only converts digital broadcast signals into analog signals. Those households may want to have a more complex and newer STB with additional features. However, households that are so far still using analog TVs (e.g., those in developing countries) will likely need a DTC to keep using their analog TVs after the digital switchover in their countries.
In the USA, the Federal Communications Commission (FCC) mandated that all US-based TV signals must be transmitted in a digital format starting in June 2009, but cable companies were not required to make the change (FCC 2009). In 2007, the US ENERGY STAR program required that the power consumption of DTCs not exceed 8 Watts [W] in “on” mode and 1 W in “sleep” mode and to incorporate an automatic power-down feature to switch from on to sleep mode after a period of time (4 h or less) without user input (US EPA 2007). According to Cheung et al. (2011), selected ENERGY STAR-qualified and non-ENERGY STAR-qualified DTCs available in 2009 consumed on average 5.4 and 7.6 W in on mode, respectively, with an overall average of 6.5 W. A research team from the Natural Resources Defense Council (NRDC) and Ecos in 2010 investigated the energy consumption of various STB types, including those with additional features. Depending on specifications, the on-mode power consumption of the products was mostly in the range of 10 to 50 W although the most efficient HD digital video recorders (HD-DVRs) consumed less than 10 W (NRDC 2011). According to NCTA (2014), US ENERGY STAR Version 3-qualified HD-DVRs and non-DVR STBs consume 21 and 15 W, respectively, and STB efficiency is expected to be further improved by 10–45% by 2017 in the USA.
For the European region in 2007, a basic STB that meets the Digital Video Broadcasting–Terrestrial (DVB-T) standard and has no hard disk (i.e., a “simple” STB) was measured to consume about 4–15 W in on mode, and an STB with hard disk consumed about 14–23 W in on mode (MVV 2007). It is important to note that standby-mode power management may save significant STB electricity consumption because evidence has been reported that a majority of consumers do not switch STBs off but instead either switch to standby using remote control or leave the STB in on mode (MVV 2007). Since 2012, simple STBs sold in Europe have been required to consume no more than 5 W in on mode and 0.5 W in standby mode, with allowances for additional features such as hard disks, second tuners, and HD signal decoding (European Commission 2009).
South Korea completed its analog broadcast switch-off at the end of 2012 and adopted the Advanced Television Systems Committee (ATSC) DTT standard. Testing of seven DTC products available in 2011 in Korea revealed power consumption ranging from 3.9 to 5.3 W in on mode and 0.4 to 1.2 W in standby mode (TTA 2011). In China, GB 25958-2010, the energy efficiency standards for DTCs, requires that the power consumption of DTCs without additional functionality not exceed 5, 7, and 10 W in on mode and 1, 2, and 3 W in standby mode for Grade 1, 2, and 3, respectively (top10.cn 2014a). Energy-efficient DTC products selected by Top 10 China (http://www.top10.cn/) in 2014 showed power consumption ranging from 3 to 5 W in on mode and 0.3 to 1.0 W in standby mode (top10.cn 2014b).
Although DTCs that primarily convert digital signals to analog signals are estimated to consume less than 10 W in on mode, DTCs or STBs with additional features such as recording require more energy. For example, the additional power consumption of hard disk and HD output with DTCs in China is required not to exceed 2.2 and 3.0 W, respectively, for Grade 1 (top10.cn 2014a). Therefore, we conclude that the combination of an analog TV and a DTC (or STB) would consume substantially more energy than a typical 20- and 21-inch analog TV alone given that CRT TVs consume between 60 and 90 W in on mode (ECCJ 2010, Park et al. 2011).
Along with the DTV transition, TV screen technology has, in less than a decade, undergone a large-scale global market transition from CRT TVs to flat-panel TVs (Park et al. 2011, 2013, and 2014). LCD TVs were estimated to account for more than 95% of new TV shipments in 2014 and LED-LCD TVs to represent nearly 100% of total LCD TV shipments (DisplaySearch 2014c, IC Insights, n.d.). The rapid improvement in cost and efficacy of LED technologies has driven the adoption of LED backlights for LCD TVs and other applications. In addition to better LED performance, viable options to improve LCD TV efficiency include optimized combinations of optical films in LCDs and improved LCD panel transmittance, brightness control functions, and energy-efficient power electronics (Park et al. 2011, 2013, 2014). In particular, major TV manufacturers have been providing new types of LED-LCD TVs at lower market prices to decrease the price gap between conventional LCD TVs and LED-LCD TVs. Manufacturers have achieved price reductions by decreasing the maximum luminance level, adjusting color reproduction capability, and redesigning the LED backlight structure (Park et al. 2014).
Although market prices for similar TV models produced by the same manufacturer vary by region, energy consumption remains largely the same. For example, the regional award-winning models of Samsung and LG in the Super-efficient Equipment and Appliance Deployment (SEAD) Global Efficiency Medal competition showed similar on-mode power consumption (see Table 1).
Although the global manufacturers (Samsung, LG, Sony, Panasonic, Sharp, and Toshiba) account for more than 60% of global TV sales, China, which has the single largest TV market (more than 20% of the global TV market), has been dominated by Chinese manufacturers that represent more than 70% of China’s TV sales (DisplaySearch 2011, Park et al. 2011, 2013). It is difficult to obtain TV power consumption data measured by the same test method for all countries, but the highly globalized nature of TV manufacturing means that data available from the USA, China, and developing countries are useful.
Based on US ENERGY STAR-qualified LED-LCD TVs (84 models), recent 23-/24-inch (16:9 aspect ratio) LCD TVs consume 16 to 28 W regardless of backlight technology (US EPA 2015a). On-mode power consumption of the ENERGY STAR Most Efficient LED-LCD TVs (18 models, 15–24 in. on diagonal) in early 2015 ranged from 0.06 to 0.11 W per square inch [W/in2] (estimated to correspond to approximately 14 to 25 W for a 23-inch TV) (US EPA 2015b). The energy-efficient 32-inch TVs (8 models) selected by Top 10 China (http://www.top10.cn/) in 2015 consumed 28 to 52 W in on mode (equivalent to 0.06 to 0.12 W/in2 estimated to correspond to 14 to 27 W for a 23-inch TV).
The Global LEAP Outstanding Off-Grid TV Awards tested a number of direct current (DC) TVs designed for off-grid use to identify the world’s highest-quality and most energy-efficient and affordable off-grid TVs. The DC TVs tested were 15–23 in. on diagonal and had on-mode power consumption ranging from 0.05 to 0.10 W/in2 (Global LEAP 2014) Table 2.
Although the product groups might not be entirely comparable (specifications such as network features, luminance default mode could be different), these models represent highly efficient TVs available in the USA, China, and developing countries. We can reasonably conclude from these data that on-mode power consumption of energy-efficient LED-LCD TVs is similar across regions.
Typical 20-/21-inch (4:3 aspect ratio) CRT TVs are estimated to consume 60–90 W per unit (ECCJ 2010, Park et al. 2011). Although replacing analog TVs with recent flat-panel TVs is more expensive than adding a basic STB or DTC to analog TVs, using energy-efficient flat-panel TVs will significantly reduce energy consumption and provide consumers with much better picture quality.