Daylight saving – energy saving or demand management?


Quito, Ecuador — (METERING.COM) — October 16, 2008 – Does daylight saving – when the time in a country is adjusted during the summer months so that the greatest number of hours occur during daylight – result in a saving of energy?

This is the question posed by energy efficiency consultant to the Latin American energy organization OLADE (Organización Latinoamericana de Energía), Mentor Poveda, in a feature in the organization’s latest bimonthly bulletin.

Reminding that daylight saving was used during the First and Second World Wars to conserve fuel by reducing the need for artificial lighting, Poveda says that at the equator there is no variation in daylight hours during the year, while in the torrid zone at 20o N between April and October the number of daylight hours varies from 12,18 hours to 13,20 hours. However, this is small compared with the variation from 12, 58 to 16,12 hours that occurs during the same months at 50o N – the latitude of Paris – and thus significant differences will result in applying the principle of energy saving in these locations.

In the case of the member countries of OLADE the majority are situated within the torrid zone, except Argentina, southeast Brazil, Chile, northern Mexico, southern Paraguay and Uruguay.

Recalling the experiences of daylight saving in Ecuador and El Salvador, Poveda comments that the load was transferred from the evening to the morning as people were then getting up in the dark and obviously turning on lights. Thus even though the evening peak demand was reduced, there was no energy saving overall.

In both of these countries a sacrifice was demanded of the population in waking in the dark, which would not be the case in countries further to the north or to the south as at the time of getting up the day is already well illuminated, writes Poveda.

“It is for this reason that in English the change of hour is named daylight saving, because one may use to best advantage the additional hours of daylight that are available during the season in which the hour is changed.”