Early this week, Spanish government announced the plan on energy saving which shall be approved today. Among the rashly announced measures, one about replacing city lights for more efficient ones raised economic controversy among local governments and town councils: the central government does not allow them to increase debt but instead forces to invest in more efficient technology!
Minister Blanco went further by setting the example of replacing lighting devices in tunnels by LED lighting saving 40% energy cost. Based on his statement, it is difficult to say whether politicians base their decisions on facts. It might well be that they have data on the lighting sources across spanish towns and data indicates there is room for improvement, but could they cite it?! Let’s be more precise: when Blanco says “LED lighting reduces 40% energy cost,what is he comparing LED to? Do you know? Does he know?
Regarding lighting efficacy, I found out an interesting document from 2009 by EnergyLab which summarizes some data. First, let’s take a look at the relative source of electric expense in Spain, which in the public sector looks relatively low compared to heating/cooling:
Second, let’s look at some relevant indicators regarding light sources: Luminous efficacy measured in lumens (amount of light observed by the human eye) per watt (electrical power consumed by the device) and half-life (in hours, given a population of devices the time at which 50% of them stop functioning):
Clearly the top performers seem to be LED and sodium low pressure. A closer look reveals that the two tables are contradictory or mix different data sources: The first table rates LED efficacy to 55 and up to 100 (considering prototypes, I understand not commercially available) but the second table reads 80-120 for LED efficacy. Also, the first table does not include low-pressure sodium lamps that (from second table) outperforms LED.
Anyway, assuming data consistency inside each table and focusing our attention to the second table (best case for LED), still sodium low pressure lamps seem to be the best option nowadays. Aren’t they mainly used in towns and roads, Mr. Blanco?