Lighting Systems in Buildings Consume

CHAPTER 1

1.1: Study Background

Climate change is rapidly increasing in our environment due to an increase in gases such as carbon dioxide and methane produced by humans and animals in the Earth's atmosphere. As humans we have a moral responsibility to control and save the environment. The built environment is one of the major impacts towards greenhouse gas emissions. Designers are now pressured to design sustainable buildings that have less impact on emissions that damage the environment. The term sustainability means to save natural resources for future generations. Many buildings indirectly use resources such as fossil fuels which are converted into energy.

Lighting systems in buildings consume some of this energy. "Lighting accounts for around 15% of the energy bill in most homes, and around 25% in commercial buildings. It is supplied by electrical power plants using fossil fuels, and is responsible for a significant percentage of carbon dioxide emissions" (Marshall 2009) To help combat how we as consumers use electric lighting an alternative can be achieved via sustainable lighting. Sustainable lighting can be defined as, "Lighting that meets the qualitative needs of the visual environment with the least impact on the physical environment."

Light is an electromagnetic radiation, which means it is partially electric, magnetic and radiates.A  Light starts off from atoms (electrons that orbit the nucleus). When energy is absorbed by an atom the electrons shift up to a bigger orbit. When the atom loses the energy the electrons shift back down to the original orbit, while the electrons shift back down they emit light in the form of electromagnetic radiation. This document will review material on lighting systems in the office environment. The document will start with a brief history of the light bulb and then go on to how humans interpret light. The document will discuss how LED technology would be utilised more in offices and discuss the importance of migrating to LED lighting systems in offices for a more sustainable environment. The thesis will include three known case studies on LED lighting installed in offices to gather and compare data in order to evaluate how LED lighting would suffice in real life environments.

1.2: Brief History

The history of modern lighting starts off with the invention of the arc light in 1810 by Humphrey Davy. This worked by connecting a battery to a strip of charcoal using two wires. The strip of charcoal was charge with electricity and glowed. 

In 1820 Warren De La Rue used a piece of platinum placed inside a tube. A current was passed through the tube and the platinum lit well but the bulb did not go into production because platinum was very expensive. A chemist and physicist Joseph Wilson Swan produced a workable electric light in 1860 which he patented as an incandescent light bulb with a filament made from carbonised paper within a partial vacuum. J. W. Swan improved on the invention in 1875 he changed the filament to a compressed and carbonised fibrous cotton thread filament. 

An inventor called Thomas Alva Edison bought Josephs Swan's patent from a company who owned the patent.A  Thomas Edison worked on the light bulb to increase the life span. In 1880 Thomas Edison invented his Bamboo fibre filament lamp which lasted for 1200-1500 hours. (Jacks 2003) In 1903 Willis Whitnew invented the tungsten filament lamp (commonly used today). The tungsten lamp had a carbon filament with a metal-coating. This stopped the problem with the bulb turning dark as Thomas Edison's bulb did. (Jacks 2003) Technology today has advanced to new methods of lighting. Light emitting diode (LED) technology is now at the centre point of attention as LED lighting has many advantages with being very energy efficient, long lasting and produces less heat compared to standard incandescent or halogen bulbs.

1.3: Dissertation Structure

The dissertation is divided into a sequel of five chapters. The first chapter focuses on climate change and the need to for a more sustainable built environment, a brief history into the light bulb, aims and objectives of this dissertation and the logic behind the dissertation. Chapter two is a detailed literature review which focuses on the effects of lighting on building occupants followed by government legislation, then comparing different types of lighting and leading onto research on LED technology. The information gathered is sourced from websites, government documents, books and scientific journals.

Chapter three follows on from the literature review. This chapter focuses on the structure for the dissertation; firstly explaining the reason for using a literature review and then drawing on three major case studies have been chosen and all cases deal with LED lighting systems within office spaces. From the case studies the author has analysed and interpreted information.A  The primary data gathered will be in the form of a qualitative questionnaire sent to lighting experts (via email) who have been involved with the case studies. The Answers have been analysed and compared to get a wide knowledge from accredited professional opinions. The fourth chapter researches into the three chosen case studies, all case studies are analysed and compared to give an overview of how effective having an LED lighting system is in an office environment.

The fifth chapter discusses the results gathered from the findings. This would give an overview to the dissertation and show the key findings into answering the key questions. The final chapter will draw up conclusions as to the impact of LED lighting in office environments. The chapter addresses the original research question in the context of the findings and provides final conclusions on LED lighting and making use appropriate references where necessary.

1.4: Aim and Objectives

The author has chosen sustainable LED lighting as the subject area in this dissertation. The question the author would like to propose will be: "Why aren't there enough office buildings using LED lighting systems? Also what effects do LED lighting have on users working in an office environment; would LEDs be beneficial for health and comfort on a psychological basis?" To address the question the author will explore this main aim:

The aim of this study is to research into the sustainability of LED lighting systems and how lighting can affect building users within an office environment. The author will aim analyse case studies on LED lighting systems in offices. What are the advantages and disadvantages? How would an LED lighting system be best suited for the office environment in terms of efficiency, comfort, reliability and short & long term costs? The author will interview people from case studies drawn to gather primary qualitative information to reach a final conclusion. The actions the author will take to help answer the research question are listed below:

• Literature review, take into account of the building regulations, effects of artificial lighting on building occupants, types of artificial lighting and researching into books, case studies, reports, journals and websites related to LED lighting and other sustainable lighting systems.
• Research case studies on LED lighting systems that have been installed in offices. This would give the author an insight on how LED lighting systems have been successful in a real life environment.
• Interview researchers from case studies. Ask questions about how LEDs are designed to fit in a working office environment. Any issues that have occurred within the buildings.

1.5: Hypothesis

In the United Kingdom there are very few offices if any that use an LED lighting systems to light up an office space. This could be due to lack of awareness, economic climate, social environment and lack of technology available to solve prob lematic conditions.

1.6: Key questions

1. How does light effect building users in terms of health?

2. How would LED lighting benefit offices and the environment?

3. Why isn't there many offices using LED lighting systems?

4. What is the current market like for LED lighting? Would there be a future for more LED lighting in offices?

CHAPTER 2

2.1: Introduction

This chapter researches into the effects of lighting on buildings occupants, legislation, different types of lighting and LED technology in detail. The aim for this literature review is to obtain information on how light is transcribed in the circadian system and the effects of light on human health. Legislation is a key issue for lighting. it regulate on the amount of light required for the appropriate tasks usually attained in different buildings, by learning legislation it would give the author an understanding into what requirements an office would need for "good lighting".

All information collated are from secondary and tertiary sources; for this literature review the information is found in books, journals, web pages, and government documents.

2.2: Effects of lighting on building occupants

Lighting affects all building occupants on the way they perform tasks. There are different levels of lighting in different environment; the colour of light used in offices would tend to have a blue-white colour to promote concentration and light used in public areas would be a warmer yellow colour so building occupants would feel more relaxed in this type of environment. Too much light can cause health problems such as increased stress levels, headaches and higher blood pressure to the building occupant. stated that "Most apparently visual tasks have three components; visual, cognitive, and motor. Every task is unique in its balance between these components and hence in the effect lighting conditions have on task performance."

Also stated that "Lighting conditions can affect task performance throught three systems, the visual system, the circadian system, and the perceptual system. the impactA  of lighting conditions on the visual system and hence on visual performance is determined by the size, luminance contrast, and colour difference of the task and the amount, spectrum, distrbution of the lighting." The point that makes is that light sent to the visual system affects the performance of the information relayed in the brain. Stated "The optical system of the human eye focuses an inverted image onto the retina, shown in Figure 1. This image is constantly changing with movements of the head and the scanning movements of the eyes. It is often said that the eye is like a camera, but the only similarity is that it forms a focused image in which, for every pixel, there is a corresponding element in the luminous environment."

"The distribution of luminance and colour that comprises the retinal image is modified by light losses that occur in the optical media of the eye, and these losses are not constant as they increase significantly with age." (Cuttle, 2008) Both books express points about how light is interpreted in the human brain differently but they both correlate how light can affect a building occupant. They both state how light is interpreted in the visual system.

A research journal on "Light - Much More Than Vision" written by Mark. S. Rea (Ph.D.) Discuses how lighting can affect the circadian system in building occupants. The journal questions if offices, school and homes are providing "good lighting" practises. The journal begins with an abstract on the impact of light on the circadian system "The amount of light, its spectral composition, spatial distribution, timing and duration needed for vision is so different from that needed for circadian functioning, that generalizations about "good lighting" will have to be assessed by two very different sets of criteria in the future."

The journal continues on how light is interpreted in the human circadian system "Light is presently and formally defined as optical radiation entering the eye that provides visual sensation. An international system of photometry has been developed and institutionalized to quantify, measure and communicate the properties of light as it affects the human vision." (Mark. S. Rea, 2007) This statement explains how light is communicated in human vision.A  Practical sources of light allow humans to read material, move around spaces, drive cars, create social interaction between other users and allow user to do other activities.

Under spatial distribution the journal states "Through optical refraction by the cornea and lens in the eye and by neural-optical enhancements by in the retina, the spatial distribution of objects and textures in the environment can be processed by the visual system. Arguably accurate rendering of the spatial distribution of light in our environment by our retina is essential to our survival because patterns of light and dark provide information needed by the visual system" The journal concludes with "So, Are we providing healthy light in our offices, schools and homes? Probably the answer is "No, we are not." Certainly we are not providing or specifiying the ideal lighting technologies and applications for the circadian regluation" (Mark. S. Rea, 2007). This would bring on the question as to wether LED lighting would provide the answer to "good lighting". LED has been evolving for years, they have been specifically modified to provide comfortable lighting levels for which a user could carry out certain visual functions.

2.3: Legislation

The Kyoto agreement is a protocol made by the United Nations Framework Convention on Climate change. This main aim of the protocol is to stabilise greenhouse gas emissions. There are four greenhouse gases that the protocol focuses on (carbon dioxide, nitrous oxide, methane, sulphur hexafluoride). The United Kingdom Government is legally tied to the Kyoto agreement and has set out targets to meet emission rates.

A document on "The Kyoto Protocol" by British-Energy states "The UK's commitment under the protocol is for a reduction in greenhouse gas emissions of 12.5% from 1990 levels by 2008-2012. This implies an 8% reduction in CO2 emissions over this time period. The UK governirational target for itself of a 20% reduction of CO2 emissions by 2010, demonstrating the importance of this issue for the current government."(British Energy, 2009) Offices contribute towards the CO2 emissions given off around the planet. A lot of the energy used in offices is mainly caused by office lighting. The new advancements in LED lighting could reduce the amount of energy used because LED lighting is the most sustainable type of artificial lighting. This could help aid the efforts of the Kyoto Protocol and help meets emission targets.

Approved Documents Part L of the building regulations is split up into four documents. Part L1A and L1B focuses on conservation of fuel and power in domestic buildings, part L2A and L2B focuses on conservation of fuel and power in non domestic buildings. As of 6th April 2006 the revised Building Regulations Part L Conservation of Fuel and Power came into effect. The updated regulations would improve energy standards by 40 percent from that of the 2002 Building Regulations.

There are four approved documents published by the Office of the Deputy Prime Minister (ODPM, 2006):

• Approved Document L1A: Conservation of fuel and power (New dwellings) (2006 edition)
• Approved Document L1B: Conservation of fuel and power (Existing dwellings) (2006 edition)
• Approved Document L2A: Conservation of fuel and power (New buildings other than dwellings) (2006 edition)
• Approved Document L2B: Conservation of fuel and power (Existing buildings other than dwellings) (2006 edition)

L1 - Domestic buildings

• Conservation of fuel and power in dwellings.
• Limiting heat loss through fabric of dwelling from hot water pipes used for space heating.
• Limiting heat loss through hot water vessels and service pipes.
• Use control systems on space heating and hot water systems so that energy can be used efficiently.
• Use control systems on lighting systems so that energy can be used efficiently.

L2 - Buildings other than dwellings

• Conservation of fuel and power in non domestic buildings.
• Limiting heat loss through fabric of dwelling from hot water pipes used for space heating.
• Limiting heat loss through hot water vessels and service pipes.
• Use control systems on space heating and hot water systems so that energy can be used efficiently.

Providing lighting systems with sufficient controls so that energy can be used efficiently.

• Limiting exposure to solar heat gains.
• Use control systems on air conditioning and mechanical ventilation systems so that energy can be used efficiently.
• Commissioning the building engineering services so that they make efficient use of energy and recording their performance.

Approved Document L2A: Conservation of fuel and power highlights what is required for lighting efficiency in offices, industrial and storage areas in all building types. The document states "For the purposes of this Approved Document, office areas include those spaces that involve predominantly desk-based tasks, including classrooms, seminar rooms and conference rooms, including those in schools.

Reasonable provision would be to provide lighting with an average initial efficiency of not less than 45 luminaire-lumens/circuit-Watt as averaged over the whole area of these types of space in the building." (ODPM, 2006 pp. 19)

LED lighting has the potential to excel past the average guide for initial efficiency of 45 lumens per watt. A breakthrough from the lighting company CREE states "LED efficacy test results that set a new benchmark for the LED industry. Cree reported results of 131 lumens per watt white LED efficacy, confirmed by the National Institute of Standards and Technology in Gaithersburg, Maryland. Tests were performed using prototype white LEDs with Cree EZBrightâ„¢ LED chips". (CREE Inc, 2009)

The CIBSE Lighting Guide 7: Office Lighting gives a guidance of how to layout lighting systems within an office to give the maximum efficiency of lighting and how much light is required for different types of office spaces. The guide states "There are many ways to light an office space: with direct light down from above, from indirect light bounced from the ceiling, or from a combination of both. Many factors will dictate or influence the choice of which technique to use."A  (Ruffles, 2005 pp. 7)

There are many different building types and each office would need a lighting system that is individually specified. There are different types of lighting systems that give off different light intensities.

The lighting guide states that a typical office space would need 500 lux (illuminance) for building users to take on paper-based or mixed tasks comfortably and 300 lux for any screen-based work. (Ruffles, 2005)

Figure 2 shows the required amounts of light need for building user to work within different types of offices spaces, taken from the office lighting guide.

The figures suggest that each typical office space would need 300 lux for screen based tasks, normal meetings and reception administrative tasks and 500 lux for more intense tasks such as paper-based, reading documents and writing. In a more deep-plan area the office space is required to have 500-750 lux throughout to perform multiple tasks comfortably. This is due to the fact that deep-plan areas are more towards the middle of office spaces or more than six meters away from windows; they would require a more constant flow of artificial light.

This is where LED lighting may be at best because of the amount of electricity LED lighting systems take are very minimal and could deliver the required amount of light depending and the type of fixture. In normal deep-plan areas artificial lighting systems are on for longer periods because natural lighting coming in from windows would not penetrate throughout the office spaces.

The corporation Philips suggests that a higher powered LED light would deliver up to 220 lumens. This type of LED would typically consume four watts. A typical deep-plan office space would require three high powered LED lights to deliver a comfortable amount of light for a user to perform various tasks, which would still consume less electricity compared to other office lighting systems.

2.4: Types of lighting

There are many types of lamps that are currently used in different environments. These lamps include the incandescent lamp, compact fluorescent lamp, fluorescent lamp, halogen lamp, metal halide lamp and light emitting diodes.

Incandescent lamps

An incandescent lamp is a glass (See figure 3) bulb containing a thin filament. A current is passed through the filament, which heats up the filament until light is produced.

(Philips, 2000 pp.49-50) stated "The earliest filament lamps as developed by Swan in the United Kingdom and Edison in the United States had a short life of only 150 hours and a low efficiency of 2.5 lumens per watt, but they were thought of as a magic light source to replace gaslight. Filament lamps were clean, had greater flexibility, better colour and, with the development of available sources of power, better long-term economics. Now, a century later, the light bulb is still the preferred lamp for domestic use due to its cheap cost.

Phillips (2000) continues to state that "The life of a filament lamp depends upon its light output, with a greater output giving a shorter life. A life of 1000 hours with a light output of 12/14 lumens per watt was established as being a reasonable compromise and one which has stood the test of time."

(Bean, 2007 pp. 139) explains that a compact fluorescent lamp is "the introduction of smaller diameter tubes using high efficiency triphosphors bought with it the posibility of folding the tubes to produce compact single ended lamps. A 12W compact fluorescent lamp gives the same output as a 60W tungsten GLS lamp".

Fluorescent Lamps

(Fielder, 2005 pp. 28) states that "Fluorescent lamps are built using a tubular glass envelope coated on the inside with a mix of phosphors. Inert Gas and a small amount of mercury is introduced into the tube to provide the atoms for photoluminescence. the tube is slightly pressurized, and the ends of the tube are capped with electrodes, which contain a cathode to generate and arc."

Fluorescent lamps are 8 times more efficient than incandescent lamps and have a long life span, but fluorescent lamps contain mercury shown in figure 5. Mercury in lamps is harmful for the environment if not disposed of appropriately.

Halogen Lamps

The Interior Lighting for Designers book articulates that "The tungsten-halogenA  (or halogen)A  lamp is an incandescent lamp with a selected gas of the halogen family sealed into it. As the lamp burns, the halogen gas combines with tungsten molecules that sputter off the filament and deposits the tungsten back on the filament"A  (Gordon, 2003 pp. 73). Figure 6 below shows an example of what a typical halogen lamp looks like.

Metal Halide Lamps

"Metal halide lamps produce white light of a good colour quality and are available in many sizes, from compact lamps that can be used in track lighting and table lamps to huge lamps for lighting stadiums. Standard metal halide lamps tend to have a colour temperature of 3700 to 4100K and appear cool and slightly greenish. Their CRI is 65 to 70. Standard metal halide lamps typically are used where colour is not critical, such as sports arenas, parking lots, landscape lighting, and building floodlighting." (Benya, 2004 pp. 9-10)

Light Emitting Diodes (LEDs)

An LED is a semiconductor device that emits light when a voltage is surged through the semiconductor.A  LED solid-state lighting is becoming more in use because of the energy saving benefits and long term costs.

The main types of light bulbs used in offices are fluorescent lamps, incandescent tungsten filament (halogen lamps) and metal halide lamps. Fluorescent lamps are the main types of light sources used in offing lighting; the table states that the fluorescent tubes has a lamp efficiency of 32-86 Lm/W (Lumens per watt) this has a higher efficiency compared to incandescent tungsten filament lamp which have an efficiency of 7-14 Lm/W. Also fluorescent lamps can last more than ten times longer than incandescent tungsten filament lamps, but the tungsten filament lamps has a colour rendering index of 99 which means that the light intensity is much higher and would provide light that is closer to natural daylight compared to fluorescent lamps. Tungsten lamps are mainly used for executive offices to give an office a more professional looking environment. Metal halide lamps are used for desk lamp for more detailed important task where more light may be required for analytical reading and writing/complex drawing tasks.

2.5: LED technology

LED technology is a fast growing lamp replacement solution in the lighting industry. LEDs contain semiconductors which are atoms of arsenic, phosphorus, germanium or other elements found in the periodic table. When electricity passes through the semiconductor visible light is emitted. Placing a number of LEDS side by side increases the increases the strength of the brightness. LED lights are also dimmable so the user could control the light intensity in a given area.

The advantages of using LEDS are that they have a 50,000 to 100,000 hour life span, they consume very little electricity, they instantly light up, LED lights do not emit UV rays, they are durable toA  vibrations they do not contain any mercury and LED emits light from any part of the light spectrum.

The disadvantages of using LED lighting are that light is distributed directly instead of evenly compared to incandescent and fluorescent bulbs; it is very expensive to buy LED lights, they could cause light pollution in an environment because LEDs produce a lot of white light and LEDs are sensitive to heat.

LED lighting is still currently being researched today to find out better methods to utilise the light from LEDs. An article from The Independent newspaper states "The Indian government hopes to remedy this situation, which affects 112,000 rural villages across the country, over the next decade. The solution is a combination of light-emitting diodes (LEDs) and solar power. The former are more efficient than light bulbs - the power required to light one conventional 100W bulb can now light an entire village - and the latter allows electricity to be stored in batteries and provides lighting where there is no grid supply. Both LEDs and solar panels can also take the rough and tumble of village life: having few moving parts, they are very durable." (Independent, 2006)

It is evident to see from this statement that the progress of utilising light from LEDs is positive; however this is not something that can be generalised to a greater population at this current time due to economics.

A journal published from the Philips Research Centre shows an experiment on LED light sources and modelling for practical control systems for LEDs. (Subramanian Muthu, 2002) states "The recent improvements in high-power light emitting diodes (LED) technology with 100+ lumens per LED chip and efficacy exceeding that of incandescent lamps brings the solid-state lighting close to a reality. An LED light source made of Red, Green and Blue (RGB) LEDs can provide a compact light source with unique features such as instant colour variability. In this paper, we highlight the issues that introduce the variability in the colour point and present feedback control schemes to overcome these problems." (Subramanian Muthu, 2002)

The journal concluded with: "RGB-LEDs have enormous potential in lighting applications. The major issue to be resolved is control and maintenance of the white point. This issue arises from the variation in LED wavelength and lumen output with temperature, drive current and time. Further complications arise due to the wide spread in the performance parameters of nominally identical LEDs. In this paper we have presented solutions to these issues using electronic feedback control of the light output of the LEDs." (Subramanian Muthu, 2002)

A journal on Fundamental Analysis for Visible-Light Communication System Using LED Lights states "LED is more advantageous than the existing incandescent in terms of life expectancy, high tolerance to humidity, low power consumption, and minimal heat generation lighting. Our group has proposed and optical wireless communication system that employs white LEDs for indoors wireless networks (8)-(11)." (Nakagawa, 2004)

The journal concludes "In visible-light communication system, the LED lights are distributed within a room and the irradiance of light is wide for function of lighting equipment. Therefore, the intersymbol interference depended on the data rate and the FOW of receiver."  (Nakagawa, 2004)

A technical report on "Energy Savings Estimates of Light Emitting Diodes in Niche Lighting Applications" from the U.S. Department of energy focuses on the energy performance of LED lighting systems within different sectors such as, residential lighting, traffic lighting, retail lighting and office under shelf lighting. the document states that "A type of task lighting, LED office undershelf lighting systems have been introduced on the market as replacements for T12 and T8 fluorescent products used in the commercial offices. LED office undershelf lights have the potential to save 1.37 TWh/yr if the entire market shifted to 2007 LED technology, equal to 14.8 TBtu/yr of primary energy consumption. This amounts to about 20% of the annual consumption of one large (1000 MW) electric power plant or the annual electricity consumption of one hundred thousand U.S. households."(U.S. Department of Energy, 2008 pp. 50)

The report also states that fluorescent lamps, T8s, and T12s are the types of lamps that are commonly used in an office environment. These fluorescent lighting systems have a fixture efficiency of less than 40%.A  This follows on to the average number of hours artificial lights operate for. "Office undershelf lighting systems operate for an average of 2000 hours per year, amounting to about 5.5 hours per day or 8 hours per work day." (U.S. Department of Energy, 2008 pp. 51)

This would bring on maintenance costs for the building owner due to bulb replacements. The life span of LED lighting systems is far greater than fluorescent lamps, which in turn would reduce regular maintenance.

The annual energy comsuption for 53 million office undershelf lighting systems consume 3.43 TWh/yr of electricity in the U.S. At the moment LED lighting systems are still new to the market and have not penetrated the market enough to calculate the actual energy savings; however LED lighting systems have the potential to save 1.37 TWh/yr of electricity if LED lights completely replaced fluorescent lighting systems. (U.S. Department of Energy, 2008 pp. 52)

(DiLouie, 2006) Points that LEDs are solid state devices that produce light by passing a current through semiconductor chips which are housed in a reflector, which is encased in an epoxy lens. "The lens converts the LED into a multidirectional or unidirectional light source based on specification".

(Dilouie, 2006 pp. 246) states the benefits of using LED lighting vs. traditional light sources:

• Very small size, increases flexibility to build lumen packages into fixture designs and extends ability to light tight spaces.
• Greater reliability, with no filaments or moving parts; durable and resistant.
• Greater energy efficiency, with 70 percent less energy being consumed.
• Safer and environmentally friendly operation, with less waste and no mercury, and no UV energy and little infrared.
• Colour-changing, ability to mix colours to generate millions of potential colours.
• Directional light source, which simplifies fixture construction.
• Ability to integrate into architectural materials and to be used to edge-light glass and plastic panels.
• Increased quality, colour and strength of light.
• Ability to start at temperatures as low as -40oC.

LEDs are slowly following major trends within the lighting market, in which there is a strong demand for lighting equipment that is more efficient, smaller, longer life span and colourful. (DiLouie, 2006) states "engineers consider energy efficiency and long service life to be the most influence attributes in their decision-making to specify LED lighting equipment." engineers are certain about specifying LED lighting in the upcoming future and could see a few obstacles to specification, but are more conservative for the use of LED technology less willing to work with the new versus traditional lighting suppliers.

Below shows three tables on the LED lighting market. This shows what the current market share are for LED lighting applications and also shows future predictions for the use of LED applications. These table are taken from the book 'LEDs for Lighting Applications' by Patrick Mottier

The LED market for LED consumption in Europe is worth $1.2 billion. The LED lighting market now is starting to become more of a commodity market where there are few European companies that are active, although companies in Europe can capitalise on semiconductors in order to lead the market in optimised performance LEDs. Asia and Japan produce the most amounts of LEDs where the market shares are worth $1.2 billion for Asia and $2 billion for Japan; these parts of the world have capitalised the market for the production and distribution of LEDs showing growth in LED applications.

The market share for various types of LED applications. The chart shows a continuous trend of LED applications increasing at a high rate. The growth of high brightness (HB) LEDs and ultra high brightness (UHB) LEDs are the main inclines shown in the chart. It is estimated that in 2010 the market share for high brightness LEDs will be worth $10.5 billion; (Mottier, 2008) states that the main applications for high brightness LEDs are mobile devices, displays and automobiles. "Today the market share of LED in general lighting is around 6%, likely to reach 10% in 2010." Even though there have been major scientific breakthroughs in LED lighting the figure could be optimistic due to changes in legislation, economic environment, awareness of LED lighting, cost and production.

2.6 Conclusion

To summarise on LED lighting it is interesting to find research into LED technology as there are many LED applications being tried and tested to find out any solid-state lighting systems that would be used in future. LED lighting has not yet peaked into mass produced lighting systems for commercial and residential use. There are still many possibilities to research into LED lighting systems that would maximise the potential of gaining more light and increasing the spread of light coming out of the LED bulbs. LED lighting is the way forward for sustainable lighting as it already has been shown that LED bulbs save more electricity and has a high efficiency rating.A  If LED lighting systems were to become less expensive then it would attract more users to invest in this technology.

The advantages of using LED lighting are far greater than using incandescent and compact fluorescent lighting, but LED lighting does lack in providing higher levels of light and would be hard to get a multidirectional light source although there are companies currently undergoing research and development projects for ultra high brightness LEDs for other office lighting applications.

CHAPTER 3

3.1: Introduction

This study researches into lighting for offices. The effects that light has on health on building users, legislation that effects the regulations set for office lighting, the types of lighting used in general and how LED lighting works and research into sustainability and consumptionA  of LED lighting.

Drawing on the literature review, the author aims it use a case study strategy to gain an insight into LED lighting systems within office environments; the author has used qualitative information to build an understanding of the scenarios. Three reliable case studies were drawn out to find out the impacts of LED lighting in office environment and to verify if the LED lighting systems actually provide efficient quality lighting and also energy efficient as claimed by manufacturers.

Lighting experts are drawn from the case studies and have been sent interview questions via email. These questions will give the author an in depth knowledge taken from the professional opinions of researchers which is used for qualitative primary research. The author is able to draw out conclusions from results and analyse qualitative data to back up information in case studies. This would show How LED light can be sustainable and work in a particular environment.

3.2: Literature Review

The review of literature is important for researching into a topic because it analyses and evaluates previous research that has been done in order to help find an answer or part of the answer of a specific topic. (Fellows,1997) states that "the review of theory and literature must provide the reader of the research report with a summary of the 'state of the art' - the extent of the knowledge and the main issues regarding the topic which inform and provide rationale for the research".

The author has reviewed books and websites which are sources of secondary research and journals and government documents which are sources of primary qualitative research. All information found in the sources were based on lighting systems and LED lighting application to find out information on health effects of lighting on humans, how office lighting is being regulated, researching bulb types showing how different bulbs function and research into the functionality, sustainability and growth of LED lighting.

3.3: Case studies

Case studies provide key information for a chosen topic in a real life environment. This is a form of primary data that can be used to analyse and compare data between other case studies to gain structural knowledge to implement conclusions for a final answer. (Gillham, 2000) states that "case studies allow room for the use of quantitative and qualitative research". The study focuses more on using qualitative research methods to apply answers to the research question.

The author had decided to use case studies in relation to office LED lighting systems. This would gave a firsthand basis for which data from real life environments could be analysed, questioned and compared to draw out key information based on how LED lighting systems had been successful in the office environments and help define a conclusion on the need for more LED lighting systems in offices based around the world.

There are three case studies based on LED lighting systems that are installed in offices. The first case study is on an office space in a building called Tower 42 which is located in the city of London; the company that was involved with providing the LED lighting solution is Philips Lighting. The LED lighting equipment had just recently been installed in February 2010. The new LED lighting equipment is expected to save 40% more energy compared to a typical fluorescent T5 installation. Philips Lighting is a major corporation in the lighting industry; Philips is recognised by ENERGY STAR as the leader in technology, design and style in the lighting market.

The second case study is on the Arrow Components office based in Mexico. The newly located office had decided to convert all the office lighting to LED lighting as part of a cost-saving initiative that began in late 2007. The LED lighting came from the sister company Arrow Electronics. The office building has a 4,500 square-foot office space which the LED lighting system covers.

The third case study was on the CREE Headquarters office based in North Carolina, USA. The Office had converted its fluorescent lighting systems to state of the art LED lighting systems. All parts of the CREE site had converted to using LED lighting in car parks, entrances, lobbies and conference rooms. The building had save 48% on energy since the replacement of the fluorescent lighting system. CREE is also recognised by ENERGY STAR for its best-in-class LED downlights.

3.2: Interview questions

In order to answer some of the key questions it will be essential to gather information from the views, opinions and knowledge base from lighting professionals with academic knowledge on LED lighting systems.

It was decided that structured interviews over the internet via email would be carried out with a small number of key opinion leaders to gather qualitative information. The data that the author has used is primary data in the form of short questions to lighting experts from Philips Lighting, Arrow Electronics and CREE. This data is expected to be reliable because the information would be given out by someone of authority with prior knowledge and a deeper understanding of LED lighting within offices making them 'elite' to study.

The first interviewee chosen was Dr. Hans Huiberts from Philips lighting - Philips Research, Cambridge. Dr. Hans Huiberts is the head of Philips Research and has a technical background as a device physicist in Polymer LEDs. His knowledge would give key information to answering the author's questions towards the dissertation. He would be a vital professional to gain opinions and technical knowledge on LED lighting in offices. The author had phoned Philips Research to ask of permission to interview Dr. Hans Huiberts via email (refer to appendix for email sent and interview questions attached to email). Unfortunately Dr. Hans Huiberts had been busy and was not able to contact back with answers for the dissertation on time.

The second interviewee chosen was Xavier Gonzalez from Arrow Electronics. Xavier Gonzalez is a regional lighting specialist at Arrow Electronics. Xavier knowledge of LED lighting would help answer questions based on the case study for the Arrow Components office in Mexico. His opinions would help give a more reliable source of data on LED lighting systems in offices. The author phoned Arrow Electronics to ask of permission to interview Xavier Gonzalez via email (refer to appendix for email sent and interview questions attached to email). Unfortunately Xavier Gonzalez was not prepared to fill out interview questions due to timescale and sensitive information was not allowed to be given out.

The final interviewee chosen was Kyle Rogers from CREE. Kyle Rogers is a Product specialist for CREE who has specialist knowledge on LED lighting systems. His opinions would address the questions in relation to the case study on CREE Headquarters in North Carolina, USA. The author had phoned CREE to ask for permission to interview Kyle Rogers via email (refer to appendix). The email was then sent out directly to Kyle Rogers with the attached interview questions. Kyle Rogers had replied back via email (see appendix) with the questions answered and also attached a useful presentation on LED lighting (see appendix). Once all the questions had been answered the interviewee was thanked and debriefed.

The data collected from the interview questions were analysed by critically reading through the information given and looked for ideas to emerge.

CHAPTER 4

4.1: Tower 42, London - Philips Lighting

4.1.1 Introduction

Tower 42 is an office and hotel tower complex owned by Tower Limited Partnership. It is currently the tallest building in the City of London and has won numerous awards.A  In January 2010 Philips Lighting had successfully converted the old lighting system to a LED lighting system in the Tower 42 9,000 square foot office space on Level 12. This is the first office space in the United Kingdom to have been completely lit by LED lighting.

4.1.2 Philips Lighting company background

"Philips Lighting is a leading provider of solutions and applications for both professional and consumer markets.

We address lighting needs in a full range of environments - indoors (homes, shops, offices, schools, hotels, factories, and hospitals) as well as outdoors (public places, residential areas and sports arenas). We also meet people's needs on the road, by providing safe lighting in traffic (car lighting and street lighting).

In addition, we deliver light-inspired experiences through architectural and city beautification projects. Our lighting is also used for specific applications, including horticulture, refrigeration lighting and signage, as well as heating, air and water purification, and healthcare.

With the new lighting technologies, such as LED technology, and the increasing demand for energy efficient solutions, Philips will continue shaping the future with groundbreaking new lighting applications."

4.1.3 Type of LED lighting system used

The LED lighting system that has been installed in the office are a mixture of Philips Fortimo LED light sources which are LED downlight modules designed for us as a functional light source that outperforms compact fluorescent bulbs and Philips LuxSpace mini LED downlights.

"The popular 600mm x 600mm Savio fittings, originally developed for use with fluorescent light sources, were adapted and optimised for use with 3 x 18W Fortimo LED light sources to create an edge-to-edge lighting appearance with a uniform and comfortable 'surface of light'.

Savio luminaires feature a patented micro-lens optic to ensure optimum light distribution and full glare control, compliant with the highest standards for office lighting. The evenness of the lighting is further enhanced by the innovative design of the Fortimo light source, which uses a combination of high efficiency blue LEDs with a separate phosphor plate to generate a bright white light with an efficiency of 62 lm/W.

The Savio fittings are complemented by 1 x 18W LuxSpace mini LED downlights in circulation areas. The compact LuxSpace fittings deliver a light output equivalent to 2 x 18W compact fluorescent lamps with a 50% energy saving." (James, 2010)

4.1.4 Advantages

• The LED lights have made significant energy savings of around 40% compared to using T5 fluorescent lighting installations.
• Maintenance costs are reduced due to long life of the LED lights.
• Improved light quality.
• Lighting is controlled by Philips Light Master Modular lighting management system. Multi-sensors are used in spaces to provide dimming to save more energy.

4.1.5 Impact to environment

• The LED lighting system uses less electricity than using fluorescent lighting. The system installed in Tower 42 has saved 40% of the energy consumption from lighting. This in turn saves on the amount of electricity that is generated from power stations which would help save on CO2 emissions.
• The LED lights do not contain any mercury which can be harmful for the environment if not disposed of carefully.
• The improved light quality gives a positive effect for the health and wellbeing of the building users.

4.1.6 Case study summary

The 9,000 square foot office space on level 12 in Tower 42 is the first office space in the United Kingdom to have been fully lit by remote-phosphor LED lights. The office space has achieved an energy saving of 40%.The combination of the LED lighting system and controls provided by Philips Lighting gave the best overall energy performance and life cycle costs. This building has set a bench mark for future generations for office to be lit by LED lighting systems in the United Kingdom. It has shown to be successful in terms of providing sufficient lighting with greater energy efficiency.

4.2: Arrow Components, Mexico - Arrow Electronics

4.2.1 Introduction

Arrow Components is an office owned by Arrow Electronics, Inc.A  In October 2009 Arrow Electronics Inc. announced that it had made cost-saving and technological improvements by installing an LED lighting system to light up the 4,500 square foot office space. This is part of a cost saving initiative that began in 2007. Arrow Components wanted to invest in a long-term solution whilst creating a showroom for LED technology for its customers and suppliers. This allows the company to use and promote the technology.

4.2.2 Arrow Electronics company background

"Arrow Electronics is a global provider of products, services and solutions to industrial and commercial users of electronic components and enterprise computing solutions, with 2009 sales of $14.7 billion. Headquartered in Melville, New York, Arrow serves as a supply channel partner for over 900 suppliers and 125,000 original equipment manufacturers, contract manufacturers and commercial customers through a global network of more than 310 locations in 51 countries and territories.

A Fortune 200 company with 11,300 employees worldwide, Arrow brings the technology solutions of its customers and suppliers to a breadth of markets, including telecommunications, information systems, automotive and transportation, medical and life sciences, industrial equipment and consumer electronics.

Arrow provides specialized services and expertise at each stage of a product's life cycle, accelerating and simplifying the journey from concept to market. Each product's journey begins with the technology innovations of Arrow's suppliers who introduce thousands of new components and computer products each month. Arrow's customers use that technology to design and manufacture products from home security systems to global telecommunications networks." (Arrow Electronics,2010)

4.2.3 Type of LED lighting system used

The Lighting system that had been installed are Dialight compact high intensity LED downlights (refer to appendix). These downlights deliver 1500 lumens of white light output in the compact LEDs which are installed in corridors, reception area and seating area. The ultra high brightness LEDs deliver 2100 lumens which are installed in the office spaces. The power consumption of the downlights is 27 watts and the life expectancy of the LEDs is 50,000 hours at 70% lumen maintenance.

4.2.4 Advantages

• The LED lights have made considerable energy savings compared to using T5 fluorescent lighting installations.
• The recessed LEDs have a lifespan of 50,000 hours
• Maintenance costs are reduced due to long life of the LED lights.
• The quality of light has improved. The building users have a more comfortable environment for which they can work in.
• The recessed LED lights are dimmable. Dimming the lights will save extra energy.
• The LEDs do not radiate heat, air conditioning expenses have been reduced which saved extra energy for the building.
• Payback period for the LED lighting system will be 2 to 3 years depending on how long the lights are on per annum.

4.2.5 Impact to environment

• The LED lighting system uses less electricity compared to fluorescent lighting. This in turn saved on the amount of electricity that is generated from power stations which would help save on CO2 emissions.
• The LED lights do not contain any mercury which can be harmful for the environment if not disposed of carefully.
• The improved light quality gives a positive effect for the health and wellbeing of the building users.
• The reduction for the use of air conditioning saves on energy generated from power stations, which reduced CO2 emissions that damage the environment.

4.2.6 Case study summary

Arrow Electronics has successfully installed an LED lighting system in its new office in Mexico for an initiative to save costs in the long term. The case study shows that the LED lighting system provides sufficient lighting for a more comfortable environment, this would improve on health and welfare of the building users, but the LED lighting system had a drawback with the cost to install the system into the building; this cost will be acquired through the payback period of 2 to 3 years. There are many advantages that the LED lighting had bought to the building such as lower utility bill, lower maintenance costs, improved lighting performance and reduction on CO2 emissions which can be harmful to the environment.

4.3: CREE Headquarters, North Carolina (USA) - CREE

4.3.1 Introduction

CREE is a company that provides solutions and sells LED solid-state lighting components. The CREE Headquarters is located in North Carolina, USA. In 2007 CREE headquarters had decided to change all the lighting fixtures to LED lighting fixtures in the car parks, entrances, seating areas, offices and conference rooms. "A study of the energy usage before and after the lighting conversion indicates that in total the new LED lights use 48% less energy than the incandescent, fluorescent and high-pressure sodium lights they replaced." (CREE Inc. 2010)

4.3.2 CREE company background

"Cree is leading the LED lighting revolution and setting the stage to obsolete the incandescent light bulb through the use of energy-efficient, environmentally friendly LED lighting. Cree is a market-leading innovator of lighting-class LEDs, LED lighting, and semiconductor solutions for wireless and power applications.

Cree's product families include LED fixtures and bulbs, blue and green LED chips, high-brightness LEDs, lighting-class power LEDs, power-switching devices and radio-frequency/wireless devices. Cree solutions are driving improvements in applications such as general illumination, backlighting, electronic signs and signals, variable-speed motors, and wireless communications." (CREE Inc. 2010)

4.3.3 Type of LED lighting system used

The office has been installed with CREE's XLamp XP-G LEDs in corridors, seating areas and reception area. The XLamp XP-G LEDs deliver 493 lumens at 92 lumens per watt and has a life span of 35,000 hours (CREE Inc. 2010). The office spaces and conference rooms are fitted with CREE's LR24 LED Architectural Lay-Ins which is designed to give high ambient lighting and consume 44W. The Architectural Lay-Ins deliver 3200 lumens and have a lifespan of 50,000 hours (CREE Inc. 2010).

4.3.4 Advantages

• The LED lighting fixtures have made extensive energy savings of 48% compared to using incandescent lighting installations.
• The XLamp LEDs have a life span of 35,000 hours and LR24 LEDs have a lifespan of 50,000 hours.
• Maintenance costs are reduced due to long life of the LED lights.
• The quality of light has improved. The building users have a more comfortable environment for which they can work in.
• The LR24 LED lights are dimmable. Dimming the lights will save extra energy used by the lights.

4.3.5 Impact to environment

• The LED lighting system uses less electricity compared to fluorescent and incandescent lighting. This in turn saved on the amount of electricity that is generated from power stations which would help save on CO2 emissions.
• The LED lights do not contain any mercury which can be harmful for the environment if not disposed of carefully.
• The improved light quality gives a positive effect for the health and wellbeing of the building users.
• The reduction for the use of air conditioning saves on energy generated from power stations, which reduced CO2 emissions that damage the environment.

4.3.6 Case study summary

CREE Headquarters in North Carolina had converted the previous lighting system and used for their own LED lighting products. The new LED lighting system had many major effects towards the building in terms of life cycle costs and sustainability. The case study showed that the LED lighting system provided a greater amount of light compared to the previous lighting system with a noticeable improved quality of light.

The building has managed to save 48% more energy compared to using incandescent lighting. The LED lighting project shows many positive outcomes such as better energy efficiency, longer life expectancy and lower electrical costs.

CHAPTER 5

RESULTS

5.1: Introduction

Drawing on the three case studies in chapter 4 this chapter analyses and compares the case studies to find out the possible trends and effectiveness of the LED lighting systems installed in the offices in relation to the research aims and objectives.

It was decided that a structured interview over the internet via email would be carried out to gain key opinions from a leader to gather qualitative information. The data that the author has used is primary data in the form of short questions to a lighting expert from CREE, Inc. This data is expected to be reliable because the information would be given out by someone of authority with prior knowledge and a deeper understanding of LED lighting within offices making them 'elite' to study. The original concept was to interview three key professionals from lighting companies and analyse and compare opinions, matters and knowledge but due to unforeseen circumstances two of the interviewees had not been able to accept the interview offer.

The interviewee that had replied back for the interview was Kyle Rogers from CREE. Kyle Rogers is a Product specialist for CREE who has specialist knowledge on LED lighting systems. His opinions would address the questions in relation to the case study in chapter 4 on CREE Headquarters in North Carolina, USA. The author had phoned CREE to ask for permission to interview Kyle Rogers via email (refer to appendix). The email was then sent out directly to Kyle Rogers with the attached interview questions (see appendix).

5.2: Case Study Analysis

The three case studies showed very positive results for energy efficiency and impacts to the environment. All three offices used different lighting brands which all gave out the same desired effect.

5.2.1 Types of lighting

The first case study Tower 42 used Philips lighting fixtures to light up the office space on level 12. The LED lighting installed was Philips Fortimo Downlights which provides 2000 lumens of light at 63 lm/W. Fortimo downlights use 32W of electricity per unit and has a life span of 50,000 hours. The Philips LuxSpace mini LED downlights use 19W of electricity and also have a life span of 50,000 hours.

The second case study Arrow Components used Arrow lighting fixtures to light up the 4,500 square foot office space. The LED lighting that was used are Dialight compact high intensity LED downlights that delivered 1500 lumens of white light. The Dialight ultra high brightness LEDs however delivered 2100 lumens which are installed in the main office spaces. The life expectancy of both the LED lighting fixtures is 50,000 hours.

The third case study CREE Headquarters used was CREE's XLAMPs which delivered 493 lumens of light with a life span of 35,000 hours. The Architectural Lay-In fixtures delivered 3200 lumens; each unit consumed 44W of electricity and had a life span of 50,000 hours.

From the data shown in the case studies each lighting product gave out different amounts of lumens which is because of each office space required different levels of light however the life spans of all the LED lights last for 50,000 hours apart from the CREE XLamps which had a life span of 35,000 hours but this is still significantly greater compared to the life spans of fluorescent lighting systems.

5.2.2 Advantages

All three case studies showed many advantages with the LED lighting systems. They all prove that LED lights have very significant energy savings, have a long lifespan, lower maintenance costs, improved quality of light and do not radiate heat which effectively lowers the energy usage for office air conditioning.

5.2.3 Impacts on environment

The case studies expressed that there are positive effect on the impact to the environment.A  The case studies had similar responses to the environment; all the LED lighting fixtures used less electricity which saves on CO2 emissions that damage that environment caused by power stations. The LED lights did not contain any mercury which is harmful for the environment when disposed of improperly. The reduction for the use of office air conditioning meant that less electricity was used and CO2 emissions given off by power stations which damage the environment would have been reduced.

5.2.4 Conclusion

All the case studies showed similar advantages and improvements. This tells the author that LED lighting systems give a positive consistency for sustainability and energy efficiency. This would set out a trend that other buildings would soon need to adapt to using LED lighting systems as they are kinder to the environment and help CO2 emission targets set by the Kyoto Protocol stated in chapter 2.

5.3: Interview Questions

1. What is an LED?

An LED, or Light Emitting Diode, is a semiconductor device which creates light when a current is applied to it.

2. What are the advantages of using LED lighting in offices?

Well made LED lighting products can provide significant gains in efficiency and longevity, over traditional lighting sources. Currently available products can be up to 10 times as efficient as incandescent and halogen lamps, or more as efficient as compact fluorescent lamps. LED lighting products can also last up to 25 times longer than traditional lamp sources. These advantages can contribute to significant cost savings over the lifetime of the LED product and reduced load on the electric grid. Also, unlike compact fluorescent lamps, LEDs do not require mercury (a toxic element) to operate, which provides an additional environmental benefit.

Certain LED technologies also provide light quality that is superior to fluorescent lighting and comparable to the "gold standard" incandescent lighting. These technologies provide an additional benefit of superior colour quality and comfort for the end users, compared to fluorescent lamps.

3. What are the disadvantages of using LED lighting in an office environment?

LED lighting is a relatively new and growing market. As with many technological advance, the initial cost of LED based products can be considerably higher than traditional technologies. This cost difference is made up in the electricity, replacement lamp and labour savings.

Also, because the market is still maturing, there are a variety of products on the market with unknown quality. While there are a few trusted manufacturers, that produce high quality, viable products, there are an enormous number of low quality manufacturers that consumers must be weary of when deciding to purchase an LED based product.

Both of these disadvantages will be solved as the market matures.

4. How is solid state lighting sustainable?

Solid State Lighting has been shown to require less overall energy in its combined production and usage than both incandescent and compact fluorescent light sources. Additionally, LEDs do not contain mercury. Many LED products are also RoHS compliant.

5. Would LED lighting fixtures meet the current standards (as stated in the C.I.B.S.E lighting guide) in offices?

Well designed LED lighting fixtures are in use around the world and meet a wide variety of lighting and efficiency standards. As with any lighting solution, the appropriate products must be used in conjunction with a solid lighting design in order to meet many standards.

6. Many offices tend to contain traditional lighting fixtures such as compact fluorescent lamps and halogen lamps. Why isn't there more LED lighting fixtures used in offices even though the technology has been available for some time?

While LEDs have be available in some form for decades, LEDs that create enough usable white light to be utilized in general illumination applications has only been available for a few years. The technology continues to advance and is making gains in market share. However, it is still a relatively new and expensive technology that often requires justification before installation.

7. Is there an issue with LED lights not being able to produce the same amount of light compared to CFLs and halogen lights? Could there be an issue with low quality LED lights in the market?

This question is very complex and requires detailed explanation. The answer to both questions are "No" and also "Yes". The LED market is quite varied. Well made LED products from high quality manufacturers should not have any deficiency in light output or light quality. However, due to the wide array of smaller, lower quality manufacturers in the market, in can be difficult for a consumer to recognize the difference between a "quality" and a "poor quality" LED product.

There are at least two programs in the United States (ENERGY STAR and LightingFacts) which are helping provide clarity for consumers, by identifying high quality products and their true performance values. These kinds of programs are invaluable in this emerging market.

8. Have there been any faults with the LED lights since they had been installed in the office space in CREE Headquarters?

I am not aware of there being any issues with the Cree LED Lighting products that have been installed at our main campus. So far the LED lighting products have been very reliable and show no signs of decreased light levels.

9. Has the quality of light improved in the office space in CREE Headquarters? Would the user be more comfortable to work in this environment?

The installed LED lighting products provided an increase in color quality, color consistency and a reduction in glare in many applications. This has lead to an overall improvement in the lighting and the feeling of the space.

10. After a certain amount of time would the quality of light given off by the LEDs decline?

Yes. While tradition light bulbs will simply "burn out", LEDs naturally experience a decrease in light output over their lifetime. The lifetime of an LED product is considered to be when its total light output has decreased to 70% of its original light output. For many well made LED lighting products, this lifetime can be up to 50,000 hours. Comparatively, traditional lamps will burn out in as little as 1,500 hours

11. Is there any beneficial health effects with the LEDs installed in the office space?

Because LED lamps do not contain mercury they reduce the risk of mercury exposure from broken fluorescent lamps.

12. How much energy has CREE Headquarters saved with the new LEDs installed?

An exact figure is difficult to account for, because the renovation has come in the form of a roll-out across our campus. However, a study that was done in 2007 showed at 48% reduction in total wattage, resulting in significant savings.

13. What are the current lighting levels in the office space measured in lux?

Lighting levels vary by application within the campus but are all designed to meet the recommendations of the IESNA.

14. Has there been a big increase in number of offices switching to LED lighting solutions? Would LED lighting penetrate the market for office lighting?

The LED lighting market has been growing tremendously over the past several years. LED lighting can provide significant benefits to the commercial lighting market. However, as with any emerging market, speculating about the future is just that, only speculation.

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