How Efficient - LED Lighting

Alan Turvey, Technical Engineer at ELECSA looks at energy efficient lighting and the different options available to contractors installing them. In Kyoto in 2009 an agreement was reached, by the majority of countries who attended the summit, to reduce greenhouse gasses emissions by reducing energy usage. The member states of the European Union agreed a series of dates to work towards. This is being implemented in England and Wales through the Building Regulations via the Approved Documents L1, in Scotland by Section 6: Energy, of the Technical Handbooks and in Northern Ireland by Booklet F: Conservation of Fuel and Power. This article will concentrate on the energy efficient lighting in dwellings, which has been estimated to account for 7% of domestic energy usage. It is worth noting that the Domestic Building Services Compliance Guide applies these regulation requirements in both new build and renovation circumstances. With the production and sale of general purpose non-clear and clear non-energy efficient lamps phased out since 2009, compact fluorescent lamps (CFL) initially became the “alternative of choice”. It is now estimated that LED technology lamps will corner 40% of the market by 2016. Lamp manufacturers have invested heavily in research and design to produce new products, such as the CFL and the light emitting diode (LED) energy efficient lamps to replace the tungsten filament general lighting service (GLS) lamps, which have been in use for over 100 years. During this time GLS lamps have become available in many styles of glass envelope and range of connection caps. The majority of these are available as LED products. The inclusion of the starter gear within the base and the fluorescing tube has a limiting effect on the variety of styles and sizes of lamp available. By virtue of their smaller light source, LED lamps are now available in many sizes and styles of envelope. Some LED lamps are designed for direct application for operation at 230 V whilst others are designed for 12 V operation. All LED lamps require a driver, which may be incorporated in the lamp for use at 230 V, or be a separate device for lamps operating at extra low voltage – typically 12 V d.c. Where a dimming capability is required then care must be taken to ensure the selected lamp and dimmer are suitable for this function, as early dimmer controls do not function with devices having low power demand. Manufacturer’s guidance should always be sought where dimmer control is desired. Lamp lumens per circuit watt Information on the packaging of energy efficient lamps includes the watts and lumens for the lamp. Dividing the lumens by the watts will give the lamp ‘lumens per watt’. This is also known as the ‘efficacy’ of the lamp and is an indication of how efficient the lamp is at converting electrical energy to light energy. For example an 11 watt 1055 lumen LED lamp will be rated at 1055/11 = 95 lumen per watt. The Building Regulations requires lamps specified as energy efficient to have a minimum efficacy of 45 lumens per circuit-watt. The aim for compliance with the building control approved document recommendations is for a dwelling’s living accommodation to have 75% of energy efficient lamps, graded on the labelling as A or B to be installed. These will be typically CFL or LED whilst some fluorescent luminaires are also compliant. Understanding the labels It is important to understand the labels that are applied to lamps. The EU energy efficiency label - The energy efficiency label on many items of equipment, such as lamps, provides a ready reference for comparing similar products. These ratings range from say E (although other minimum values may also be used) to A++ (or even higher). Lamp output colour - Once we move beyond the basic installation of luminaires and desire to create an effect by the use of light, the design of any lighting system will inevitably become more complex. Factors which will have to be considered will include, amongst other things, what type of work is to be carried out, the response desired from the person seeing the location and the like. Often the effect is to elicit a feeling rather than to highlight one aspect in particular. One effect to be considered is the lamp colour output. Lamps are available with different colour output for use with different applications and, although not an energy efficiency requirement, should be considered for its aesthetic effect. A general purpose lamp in a domestic location would have, typically, a warm white output equivalent to 2700 K to 3500 K. Candle light is typically at 1800 K whilst sunlight can be over 5000 K. Particularly where energy efficient lamps are replacing or being installed adjacent to existing lamps of a different type, the client should be consulted as to their preferences to ensure adequate account has been taken of the differences that lamps colour output. Cost /saving Although energy efficient lamps are more expensive to buy than the traditional tungsten filament lamp, when considering the reduction in energy cost and the extended life claimed by manufacturers, energy efficient lamps will provide a considerable overall cost saving to the consumer. Typically the savings are 75% of energy consumption along with the lifetime comparison as below: Incandescent tungsten filament Compact fluorescent (CFL) Light emitting diode (LED) Lifetime hours 1000 10 000 25000 Energy watts 60 11 7 Relative cost (£) 0.3 2 9 Lumens per watt 10 54 86 Cost for 50 000 hours (£) 465 93 70 Caption: Comparison of performance and costs for GLS, CFL and LED lamps Information on energy efficient lighting may be found:- On the website for the Energy Saving Trust www.energysavingtrust.org.uk In Approved Document L available from the DCLG web site as is the Domestic Building Services Compliance Guide - DCLG Technical Handbook for Scotland at www.scotland.gov Booklet F1: Conservation of Fuel and Power may be found at www.dfpni.gov.uk Downloads and other information can be found at www.novelenergylighting.com