Digital Billboard Energy Use in California

Billboards are outdoor signs typically large in size (14 feet by 48 feet to as large as 20 feet by 60 feet) and located along highways and busy surface streets. Traditional or “static” signs are comprised of paper panels lit at night with HID, fluorescent, or LED flood lamps. Digital billboards (DBBs), on the other hand, are comprised of hundreds of thousands of LEDs that display pixelated content on a continual basis. The main appeal of DBBs is that they allow for dynamic, bright, eye-catching advertisements that can notify drivers of targeted opportunities or real-time information and alerts. Unlike traditional static billboards, advertisements on DBBs can change easily and frequently, and can be tailored to the season, day of the week, time of day, or even to the minute.

DBB sales and installations in the United States have increased dramatically over the past decade. The rise in DBB sales is partly driven by the significant increase in revenue generated by these products over static billboards, as owners of DBBs can sell to several different advertisers simultaneously in a given month, compared to static billboards which only display one advertisement at a time and therefore can only sell space to one advertiser at a time.

Since DBBs are comprised of hundreds of thousands of power consuming LEDs, most of which are illuminated 24 hours a day, it is important to better understand the significant energy impacts of DBBs in California. Previous reports studying the energy use of DBBs present up to a six-fold difference in annual energy use (AEU), ranging from around 50,000 to over 300,000 kilowatt-hours per year, among equipment from different manufacturers installed around the country. However, DBB efficiency has improved as LED technology has matured, and today, annual energy use of new products is likely to be on the lower end of that range. Nevertheless, even among products manufactured today, there is a large range in performance between different manufacturers. Understanding what accounts for this wide variation in energy use, as well as identifying strategies to improve the overall efficiency of DBBs, will be examined in this report.

To characterize the energy use of DBBs for this report, information was obtained from primary and secondary sources to understand the basics of the technology, major market actors, installation trends, and market drivers, focusing on California when appropriate. Primary research included interviews with four out of the five major DBB manufacturers in the U.S., as well as one of the largest outdoor advertising companies in California. Secondary research was comprised of reviewing existing studies, news articles, and information from manufacturer and sign owner websites.

Through our research it became clear that energy measurement methods and references to energy consumption are not uniform. In this report, we outline the different metrics commonly used to characterize DBB energy use and propose a possible method for standardizing energy consumption reporting based on area and brightness levels. Incorporating some key assumptions about brightness levels, operating conditions, size, and display content, we calculated a typical, current generation DBB (14 feet by 48 feet) to use between 29,000 and 94,000 kilowatt-hours per year. Based on our estimate of 250 to 300 DBBs installed in California, this corresponds to a range in statewide energy use of between 7 and 28 gigawatt-hours per year, with a potential to increase significantly based on increased installations.

By focusing on the two energy saving measures that offer the greatest potential, high quality LEDs and tighter brightness control settings, we estimate that power reductions of up to 85% are possible, between the best and worst products. This translates to potential annual energy savings of around 80 megawatt-hours per sign, or up to 1.36 gigawatt-hours savings per year for the installed base of DBBs in California, based product performance data provided by manufacturers.

These estimates relied on several assumptions that could be refined through additional research. In order to more accurately characterize DBB energy use, the following future research opportunities are outlined at the end of the report: field monitoring, teardown analysis, utility data analysis, cost analysis, scope expansion to cover on-premise signs, and test procedure development.