DOE Report on Energy Consumption & Lighting

In order to plan its SSL R&D program effectively, DOE needs an accurate and comprehensive picture of the U.S. lighting market and its energy consumption. That information has been painstakingly collected and is presented in a new DOE report, the 2010 U.S. Lighting Market Characterization, which will be of considerable interest to many in the industry. Available online at www.ssl.energy.gov/tech_reports.html, the LMC is an update to a similar report that looked at the 2001 market and provides a useful comparison.

The new report looks at how many light sources of each lighting technology were installed in the U.S. in 2010, where they were installed, how much energy they consumed, and how the U.S. lighting market characteristics changed over the decade. Developed using building-lighting audit data, industry surveys, national lamp shipment data, and interviews with lighting professionals and subject matter experts, it focuses on four sectors: residential buildings, commercial buildings, industrial buildings, and outdoor.

In 2010, lighting accounted for roughly 700 TWh, or about 19 percent of the country's total electricity use (to give you some idea of the magnitude, 1 TWh = the total energy used by about 32,500 U.S. residences in a year). Nearly half of that energy use (349 TWh) came from the commercial sector, which was dominated by fluorescent lighting. Although the residential sector (175 TWh) contained far more installed lamps (nearly 6 billion, compared with just over 2 billion commercial lamps), most of them incandescent, these residential lamps saw less than one-fifth the daily use, on average, of commercial-sector lamps. The outdoor and industrial sectors each accounted for roughly 2 percent of all lamps installed but saw even more daily use on average than the commercial sector, resulting in substantial energy consumption (118 TWh for outdoor, 58 TWh for industrial).

During the period between 2001 and 2010, a number of overall trends emerged. For example, there was a notable push toward higher efficacy. The average system efficacy of installed lighting increased from 45 lm/W in 2001 to 58 lm/W in 2010 (calculated by dividing total light production by total energy use, so that lamps of very low or very high efficacy that are little-used don't affect the average disproportionately). This was mostly due to several changes spurred by investment in more energy-efficient technologies, federal and state lighting regulations, and public awareness campaigns – namely, moves from incandescent to CFLs in the residential sector, and from T12 to T8 and T5 fluorescent lamps in the commercial and industrial sectors.

The latter trend was especially pronounced, as the number of installed T8s in the commercial and industrial sectors rose from 580 million in 2001 to more than 1 billion in 2010, with T5s skyrocketing from 6 million to 107 million during that same period – while less-efficient T12s declined from just over 1 billion to 610 million. CFL use also rose considerably, with the number of installed CFLs in all sectors increasing from ~227 million in 2001 to ~1,551 million in 2010.

Increases were also observed for high-intensity discharge (HID) lighting (105 million installed lamps in 2001, vs. 144 million in 2010) and high-pressure sodium (HPS; 44 million in 2001, vs.66 million in 2010). Although there was an increase in the total number of installed HPS lamps regardless of application, the number of HPS streetlights actually decreased – from 38 million in 2001 to 36 million in 2010. By contrast, the number of LED streetlights – one of the applications for which SSL has already shown that it can compete with incumbent technologies – increased during that same period, from none in 2001 to more than 1.5 million in 2010.

There was also an increased demand for light, with the total number of lamps installed in U.S. stationary applications (that is, excluding cars and other vehicles) growing from just under 7 billion in 2001 to more than 8 billion in 2010. Most of this growth occurred in the residential sector, mainly due to an increase in the number of households (which grew from just under 107 million in 2001 to more than 113 million in 2010) and a rise in the average number of sockets per household (from 43 in 2001, to 51 in 2010).

Ranked by technology, linear fluorescent lighting was the biggest consumer of lighting electricity in 2010, at 42 percent – followed by HID (26 percent) and incandescent (22 percent). Despite solid-state lighting's growth over the past decade, its penetration into general illumination applications in the building sectors was still well below 1 percent in 2010, with its major impact over the previous decade limited mainly to niche applications such as traffic signals. The report notes that SSL technology will need continued support in R&D and market adoption to achieve significant market penetration, without which it won't fulfill its considerable potential to save energy and, ultimately, cost.

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