Metrology for Solid State Lighting – Exhibition stand

The EMRP project Metrology for Solid State Lighting has produced a portable exhibition stand to encourage consumer acceptance of solid state lighting (SSL) products. The stand provides a comparison between SSL products and existing lighting technologies, such as incandescent and compact fluorescent lamps.

Based at the National Physical Laboratory (NPL) in the UK, the stand illustrates many of the key issues involved in choosing energy efficient lighting. These include; light output, energy consumption, colour, lifetime and labelling. This will help to raise the profile of solid state lighting and the important work of the project, which is funded by EMRP Call 2009 – Energy.

Solid state lighting uses light emitting diodes (LEDs) to produce light and can be ten times more energy efficient than traditional light bulbs. However, people’s perception of light is very important to the eventual public approval of any new lighting technologies, and solid state lighting is no exception. Some types of energy efficient lighting have been criticised in the past because they have different characteristics to traditional incandescent bulbs, whether having different colour properties or taking longer to turn on or off. It is therefore vital for the success of LED lamps that these types of characteristics are understood by the people who buy the products.

The new exhibition stand consists of four identical boxes that each feature a light fitting and a power socket with a power meter that displays the amount of energy used by the lamps.

The boxes are painted inside with a matte white finish and are deep enough to give a reliable impression of what the light would look like in a normal room in someone’s home. Unlike the majority of light boxes, these are designed so that the entire lamp is visible within the box, as the form of the lamp itself can be an influencing factor when choosing a lighting product.

The variations in light emitted by the different types of lamp, and by different individual products, can be seen in the boxes with the naked eye, but by wearing special glasses, which act like a prism splitting the light into its component parts, people can see for themselves the spectral characteristics of each light. This allows the public to interact with the lights in a new way and understand how the spectral characteristics reflect their overall perception of the different lamps. These spectral characteristics influence not only how well lighting reproduces the colour of common items such as food and textiles, but can also be used to assess the health benefits and effectiveness of lighting for different applications.

The power meter display, which is visible in each of the boxes, can show not only how much electrical energy each of the lights is using, but also the power factor – the ratio between real power and apparent power in an AC electric system. This is an important measurement because a lower power factor means more current drawn into the circuit and more wasted energy. The electricity supply therefore needs to work harder to supply the power. This leads to energy losses in energy distribution, which can result in additional costs to the user. Certain lighting technologies, e.g. compact fluorescent bulbs (CFLs), naturally have a lower power factor than others, but this also varies from product to product.

While the stand can demonstrate light perception and the energy efficiency of the different technologies, there are other factors that would need to be imparted by the exhibitors themselves. Sustainability issues may arise from the use of certain materials such as mercury, which is present in compact fluorescent lamps, or aluminium, which is used as a heat sink in LED lamps to keep them at their best operational temperature. The lifetime of the lamps is also important, as this relates to cost efficiency, and conservative estimates suggest that modern LED lamps, although initially more expensive to purchase, last around 25 times longer than incandescent bulbs. These issues will all contribute to the discussion around lighting technologies and it is important to give a complete picture so that informed choices can be made.

The stand has been used at various events hosted at NPL, including the Protons for Breakfast science course covering light and energy. It is intended that the stand will be used at the euroLED 2012 event and it will be made available for each of the EMRP project partners to demonstrate the range of lighting technologies available in their regions. The stand was used at the recent NPL Open House event where over 2,500 visitors saw for themselves how far energy efficient lighting has come in the past few years and how the Metrology for Solid State Lighting project is contributing to this progress.

Contact: Paul Miller (

Project Website:


Select your area of interest