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17. Energy efficient and effective lighting

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Nobody really notices lighting until there's something wrong with it. It's too bright? It's too dark? Maintenance bills have gone through the roof? Paradoxically, because it is more visible to users than many other building services, it is often the first thing that they think about when considering energy saving and carbon emissions.

In this issue of Intelligent Energy Insights our Lighting Consultant Kristina Allison BA (Hons) MA AMSLL AMILP explains how to achieve the benefits of energy efficient and effective lighting.

She covers the following topics:3450_kristina - - becky

  • The lighting revolution
  • Designing new lighting schemes
  • The energy effective methodology
  • Steps to energy effective lighting
  • The colour of light
  • Retro-fit, renew or refurbish?

Click here to see all Intelligent Energy Insight topics

John Treble, Managing Director

The lighting revolution

Legislation3450_insight17-1 - - becky relating to inefficient lamps and other poorly performing lighting products has caused the demand for energy-efficient products such as compact fluorescent lamps (CFLs) to increase and has driven the whole lighting industry to embrace other new lighting technologies to reduce energy consumption.

In 2009 a huge lighting revolution began – incandescent (tungsten filament) lamps were phased-out, starting with the common 100W. The legislation also covered discharge lamps, fluorescent and mercury, with poor efficacy operating through electro-magnetic ballasts. Now we have reached the end of the phase-out programme and in September 2013 the initiative is due for review.

Over the past 4 years the lighting industry has dramatically evolved to embrace 21st century electronic lighting in the form of light emitting diodes (LEDs). The EU chart Energy Saving vs Energy Consumption illustrates how successive technologies have driven down energy consumption until, for LEDs, it is less than 20% of that of incandescent lamps.

A recent article by the US Department of Energy (DOE) predicted that by 2030 LEDs will represent 75% of all lighting sales and Philips Lighting predicts that 503450_insight-17-2 - - becky% of their sales in 2015 will be of LED products as shown by its graph.

LED lighting is a new and exciting technology; its energy saving benefits and design flexibility have created interest from high profile retail brands to domestic users. It is crucial that a new light source is understood in order to get it right – the first time. For example, an LED solution can provide fantastic energy savings of anything up to 95% in some cases but can be totally inappropriate for other applications regardless of the energy savings made.

Designing new lighting schemes

A new lighting scheme should provide an upgrade to the existing lighting and not be perceived as a down-grade because unsuitable energy efficient products have been used. This outcome can be easily avoided by understanding the key principles when buying lamps in order to identify suitable luminaires with minimal energy waste and by recognising the requirements to successfully light the application: light the application, not the space. This means selecting the correct light level or illuminance (measured with a light meter in Lux or lumens per m2). We often see vast areas of unoccupied carpet blasted with bright light when task lights on desks would be more efficient.

Often excessive numbers of light fittings (also known as luminaires) are installed in much the same way as many other building services are over specified. In some cases this is because the product selected is poor at delivering light – ie it has a low lighting output ratio (LOR), a term used to describe how much light produced by the lamps actually gets emitted from the luminaire. A low LOR of about 50% is evidence of a poor performing luminaire, and a clear indicator of inefficiency and wasted energy. A luminaire with a LOR of 75% or more can be considered as acceptable. The higher the LOR the better.

The energy effective methodology

“Energy Effective Lighting” is a phrase coined by David Matyus-Flynn. The thing that makes this methodology stand out among others is its practical relationship to the application.

It’s a simple principle, but what most people forget, or do not understand, is that while being energy efficient is good, the lighting also needs to be effective in order to be successful. It is essential to get it right the first time, and avoid having to go through unnecessary trial-and-error processes. For example, if you choose the most energy efficient lamp available and fit it in a luminaire with a 50% LOR, you will still be wasting energy.

Fundamentally there are three main things to consider when creating a lighting specification:

  • lamp type
  • luminaire
  • effectiveness for the application

Breaking these points down into practical terms and combining the theory of practical use and energy performance will help you on your way to creating a successful energy efficient and effective lighting scheme.

Steps to energy effective lighting

The first aspect is design – no-one wants an ineffective lighting scheme. Second is maintenance – leaving maintenance staff to deal with real maintenance issues instead of changing lamps. Third is energy – energy efficiency is not much use if the first two are neglected. The fourth point is lighting controls. Specifying lighting controls, typically reduces energy consumption by a further 30%. These might be passive infrared (PIR) for presence detection, automatic dimming for daylight compensation or involve an “all singing all dancing” system with a digital addressable lighting interface (DALI).

The colour of light

No 3450_insight17-3 - - beckydiscussion of lighting is complete without a mention of colour. Correlated colour temperature (CCT), in degrees Kelvin, quantifies whether a light source appears “warm” at 2700-3000K or “cool” at about 4000K. The former tends to be used in domestic situations and the latter in office environments.

Colour-rendering index (CRI or Ra) is a measure of the ability of a light source to show the colour of an object as it would appear in daylight which is deemed to have a 100% CRI. Thus, the higher the CRI, the less colour distortion. Restaurants and supermarkets tend to get it right but the food on offer in some canteens can look less appealing!

The additional suspended luminaires in the supermarket photograph use a warmer white, with a high colour rendering lamp to enhance the appearance of the fruit and vegetables on the shelves.

Retro-fit, renew or refurbish?

Various options may be available to you depending on the state of your existing lighting scheme and the size of your budget.

If the luminaires are in good condition, replace the existing lamps with T8 eco fluorescent or LED lamps. If the existing luminaires currently use switch-start ballasts, by replacing the existing fluorescent tubes with T5 tubes using T5 retro-fit electronic adaptors can reduce energy consumption and improve lamp life.

Luminaires that use the old type of inefficient switch-start ballasts could be upgraded by replacing the excisting ballast with an electronic ballast. Renewing luminaires using this method will provide up to 90% energy savings.

If this solution is considered, a simple luminaire should be sent to a testing facility such as the Lighting Industry Association to ensure that the electrical safety of the luminaire has not been compromised.

It is, of course vital to compare the energy consumption of the system as a whole – not just the light sources – with that of proposed new systems.

Whatever maybe the best solution for your organisation it is well worth having an independent professional assessment of the opportunities for you to reduce energy consumption and improve the environment for the people that occupy your buildings.

Your Independent RISK FREE Solutions

A Green Consultancy Lighting Health Check will identify and prioritise opportunities for improving your lighting systems and reducing energy consumption and carbon emissions. When you have decided to upgrade your lighting and/or its control, we will be pleased to provide a detailed Lighting Feasibility Study or Design.

For more information click the above links or call John Treble on 01761 176300, or email John@GreenConsultancy.com

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