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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.” (Service Lamp Corp. 2001)
Light is an electromagnetic radiation, which means it is partially electric, magnetic and radiates. 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. (Sarlina 2009)
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. (Jacks 2003)
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. (Jacks 2003)
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. (Jacks 2003)
An inventor called Thomas Alva Edison bought Josephs Swan’s patent from a company who owned the patent. 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. 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.
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?
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. (H.E.S.E, 2009)
(Boyce, 2003 pp. 160) 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.”
(Boyce, 2003 pp. 160) also stated that “Lighting conditions can affect task performance throught three systems, the visual system, the circadian system, and the perceptual system. the impact 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 (Boyce, 2003) makes is that light sent to the visual system affects the performance of the information relayed in the brain. (Cuttle, 2008 pp. 5-6) 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.” (Mark. S. Rea, 2007)
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. 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” (Mark. S. Rea, 2007)
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.
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 government also has an aspirational 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 (ODPM, 2006).
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 EZBright™ 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.” (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.
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”.
(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.
The Interior Lighting for Designers book articulates that “The tungsten-halogen (or halogen) 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” (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. 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 to 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%. 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
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