Street lighting meter administration and PECU arrays
In October 2009, Government published its response to the Consultation on the Draft Order to Implement the CRC Energy Efficiency Scheme (CRC). The inclusion of unmetered supply that is a dynamic supply is classified as a CRC supply and reportable for the purposes of CRC qualification or footprint and annual reporting and qualifies for the Early Action Metric benefit.
Unmetered supply is split into three categories, known as dynamic, passive, and non-half hourly, depending on the method used to calculate electricity consumption for billing purposes.
A passive supply allocates the un-metered consumption across the half hourly periods by a mathematical relationship of annual burning hours to the daily time of sunrise and sunset. As of February 2010 this will not be included for CRC submission for April 2011. The methodology used to calculate passive supplies is generally less accurate, because it does not account for the actual switching times (e.g. the times that street lights are switched on and off) but uses an inventory based algorithm. This definition covers electricity consumption where the amount of electricity supplied is not necessarily measured by a meter.
A dynamic supply allocates the un-metered consumption across the half hourly periods by reference to the operation of a number of representative Photo Electric Cell Units (PECU) in an 'array' or by making use of actual switching times reported by a Central Management System (CMS). The CRC definition for pseudo half hourly measured supply captures dynamic measured supplies and is the most common form of pseudo half hourly measured supply. The fact that the consumption is calculated in relation to actual switching times makes it more robust.
The Central Management Systems, also known as telemanagement, is a system to remotely control street lighting. Using a CMS the operator can choose exactly when to switch each individual street light on or off and/or by how much to reduce the lamp power.
This allows any number of switching events and/or dimming levels, which can result in lower costs and carbon reductions. Alternatively lighting in town centres can be raised for peak periods and then lowered after shopping closures maintaining safety levels but taking away the excessive levels associated with conflict areas. However, the capital investment required using a CMS is often a barrier to this type of street lighting capability.
For information on street lighting, potential efficiencies and its relationship under the Carbon Reduction Commitment Energy Efficiency Scheme, please see our street lighting fact sheet Opens in a new window, and the Elexon website Opens in a new window.
