Lighting Design - The Basics of Good Lighting Design

Visual History 

Just as the physical strength decreases as one age, so does the impairment of vision occurs. The eyes continually exhibit age-related performance as one reaches the 60s and above. Some of these age-related performances include presbyopia, which is the normal loss of the ability to focus near objects ( Arth et al., 2017) . For instance, patients experience difficulties in seeing small print clearly as well as the text messages displayed in technological devices such as mobile phones. Under normal circumstances, the information of vision travels in separate pathways for each of the visual fields in the primary visual cortex. The cortex is made up of each half comprising of the right and the left thalamus, which forms the visual fields. When light enters the eye from the right hemifield, it hits the left section of the retina on the rated surface of both the left and the right eye ( Simon et al., 2015) . Combination of the inputs from each eye takes place at the optic chiasm, where the light travels to the left lateral geniculate nucleus located in the thalamus. 

The light then travels to the primary visual cortex of the left hemisphere ( Bellia et al., 2011) . Once the light has entered the eye from the left hemifield, it strikes the right half of the retina, which perceives the signals and sends them to the right visual cortex and then to the right half of this cortex ( Laughton & Say, 2013 ) . Deviation from the normal may be caused by muscular degeneration, glaucoma, myopia, and hyperopic, which are the primary defects that occur as one age. The figure below displays the interaction between the primary visual field and the eyes in the creation of a visual field under normal circumstances. 

Figure 1: Anatomical and Physiological characteristics 

Visual defects such as muscular degeneration occur in the deterioration of the central portion of the retina, which is located in the inside back layer of the eye. In this case, the retina is impaired in terms of recording images that one sees, where it is unable to send these images via the optic nerve from the eye to the brain ( Cochrane, 2014) . The macula is the central portion of the retina that is responsible for carrying out functions such as focusing of the central vision in the eye in as much as it controls the ability of the person to read, drive a vehicle and differentiate colors and objects in their fine details. As one age, there are two types of muscular degeneration that occur, which include the dry and the wet eye degenerations. The difference is that the wet eye degeneration occurs when there is a leakage in blood to the serum as one age, while the dry type of macular degeneration does not involve the leakage of blood to the brain ( Bellia et al., 2011) . Instead, the dry macular degeneration involves the formation of the yellow deposits known as drusen at the lower surfaces of the macula. 

On the other hand, myopia is a shortsightedness defect that results from the elongation of the eyeball or the steep cornea. In this case, the rays of light are focused in front of the front side of the retina, which causes visualization of distant objects as being blurred. The elongation of the eyeball is associated with aging, while it can be corrected by the use of concave glasses, where they spread the light out before reaching the convex lens of the eye, which lets the image focus to occur directly on the retina. On the contrary, hyperopia is an eye defect that results in light being focused on the retina, which results in the vision of blurred objects in the near distance. The condition occurs when the eyeball is shortened as one age ( Simon et al., 2015) . The condition can be easily corrected by the use of the convex lens, where they refract the light. The convex lens bends the light rays inwards, where they end up on the retina. 

The other defect of the eye that is experienced as one age is the development of cataracts. Cataracts are caused by the clouding of the clear lens of the eye ( Hsiao & Tsai, 2015) . Such people visualize cloudy lenses as though they are looking through frosty or fogged-up windows. At an early stage, cataracts cannot disturb the functionality of the eyesight, where they become severe as one age. The cataracts are histologically characterized by the formation of the anomalous bladder cells that lead to the formation of the aberrant lens fibers ( Arth et al., 2017) . The substance in the lens metamorphoses, leading to the formation of the eosinophilic balls, which may macrophage in response to the eye. As one age, the liquefied cortex leaks out of the lens, leading to the microphage response in the eye. While the microphage response is being experienced, the retained nucleus that is not liquefied fall to the lower layers of the capsular envelope, which constitutes the morgagnian cataract. Correction of the development of cataracts may involve corneal refractive surgery such as LASIK. 

Refraction 

The law of refraction is governed by the behavior of light rays propagating across a sharp interface created by two transparent dielectric media. The law states that light traveling from one medium to the other medium bends or is refracted ( Laughton & Say 2013 ) . The law can be used to find the amount of bend of light as it propagates through two different media. Just like the case of reflection, refraction involves the angles of propagation of light, including the incident and the refracted ray with the normal ray lying to the surface of the point of reflection. It should be emphasized that unlike reflection, refraction is dependent upon the media through which the rays of light travel. The dependence is made explicit by the law of refraction through the refractive indices, which are the constants for a given media ( Hsiao & Tsai, 2015) . In analyzing the law of refraction, consider a light ray that is incident on a plane of surface separated by two transparent dielectric media 1 and 2 as depicted by the figure below. Considering the law of refraction, the incident, the refracted and normal rays to the interface will all lie in the same plane. This can be shown by: 

In this case, θ 1 is the angle subtending the incident ray and the normal ray to the interface, while θ2 is the angle subtending the ray of refraction and the normal ray at the interface. The refractive indices n1 and n2 are for the first and second media respectively. This implies that the law of refraction can predict that a ray of light will always deviate more towards the normal in the medium that is optically denser ( Bellia et al., 2011) . This implies that the law of refraction can be used in the atrium of a public building, where the light rays will always deviate towards the medium having a higher refractive index. It should be noted that the refractive indices of the second medium (n2) are greater than that of the refractive index of the first medium (n1) as shown in the figure below. The law of refraction holds for interfaces that are non-planar, for as long as the normal to the interface at any given point is considered to be normal to the localized tangent plane of the interface at the point of consideration. 

Figure 2: Law of Refraction 

Recalling that the refractive index is the square root of the dielectric constant, the formula is defined by

Here, n is the refractive index, while K is the dielectric constant. The law of refraction holds if the speed of propagation of light through a dielectric medium decreases with the increase in the refractive index of the medium. In this case, the speed of propagation of light is inversely proportional to the refractive index of the medium. In the case of the atrium of a building, the light incidents through the normal achieve the angle of zero, which implies that the angle of refraction is zero ( Laughton & Say, 2013 ) . In this case, the law fails considering that the surface of separation of the 2 media is normal. 

Considering the case of the atrium of a building, the internal light shelf can improve the way light becomes uniform in a room and provide the solar shading without significantly increasing the illuminances at the back of the room. By consideration, the light shelves work best in a room having external obstructions, where they are known to increase the illuminances by more than 15% as the case of a story building having an atrium ( Arth et al., 2017) . The atrium of the building is the best top-lighting strategies. In this case, the strategy involves provision of light in a horizontal or slanted opening in the roof of the building, which is designed in such a way that it captures sunlight when the sun reaches the highest levels and diffuses its light from to the Zenithal area of the sky vault, where it introduces the light into the portion of the room under the skylight. This penetration pattern is controlled by the law of refraction. 

Question 2: Chromaticity and the Color Wheel 

Chromaticity 

The blackbody is a physical body absorbing all the incident electromagnetic radiation, where it does not depend on the frequency or the angle of incidence. At thermal equilibrium, a black body emits blackbody radiation, in which case, the temperature is constant. The human eye has three types of sensors responding to different ranges of wavelengths as shown in the chromaticity diagram above. On the contrary, the concept of color is only divided into two parts comprising of brightness and chromaticity. The chromaticity specifies the quality of color regardless of the levels of luminance ( Cochrane, 2014) . The chromaticity above has two parameters that can be specified as the hue and the colorfulness, where the colorfulness is the level of saturation. Since the concept of color is divided into the brightness and the chromaticity, colors such as white are considered to be bright, while color grey can be considered to be the less bright version of the same white color ( Prado-Gotor et al., 2015) . This implies that the chromaticity of the white and grey color is the same while their brightness is different. In the diagram above, the Y parameter is the measure of luminance of a color. On the other hand, the chromaticity of a color is specified by deriving the x andy parameters, where two of the three normalized values become the functions of the three tristimulus values represented by X, Y, and Z as shown below. 

The figure above depicts that the outer curved boundary is the spectral locus, where the wavelengths are represented in nanometers. The diagram specifies how the human eye experiences light with a specific spectrum ( Arth et al., 2017) . The major setback is that it cannot specify the colors of objects bearing in mind that the chromaticity that is observed while viewing an object is highly dependent on the source of light. The diagram is a representation of the chromaticities that are visible to the human eye. They are depicted in the form of color in the gamut region of the human vision. The gamut of all visible chromaticities as shown in the CIE plot is tongue-shaped. The curved age of the gamut represents the spectral locus, where it is equivalent to monochromatic light with each point representing a pure hue of a single wavelength calibrated in nanometers. The straight edge as shown in the lower section of the gamut is the line of purples. The colors do not have counterparts in monochromatic light even though they are on the border of the gamut ( Hsiao & Tsai, 2015) . The colors that are less saturated appear in the interior of the gamut with the white color shown at the center. This implies that the visible chromaticities correspond to the values of x, y, and z that are greater than zero. This means that selecting two points of color on the chromaticity diagram will mean that the colors lying in a straight line between these two points can be found by mixing these selected colors. It then follows that the gamut of these colors forms a convex shape. 

The concept of the blackbody radiator is governed by the Wien’s law of displacement, which states that there is a positive correlation between the increase in the temperature of the blackbody radiator and the overall energy radiated, where the peak of the radiation curve shifts to the shorter wavelengths when there is an increase in the temperature as shown in the chromaticity ( Kirillova et al., 2015) . The inverse is also true that when the temperature of the blackbody radiator reduces, the overall energy radiated will also increase, which will, in turn, lead to the shift of the radiation curve towards the longer waves as shown in the diagram above ( Prado-Gotor et al., 2015) . In this case, the product of the wavelength of the peak and the temperature is considered as the constant in the Plank radiation formula given by: 

In this case, the wavelength of the peak of the blackbody radiation curve results in the measure of the temperature. The radiation curves as shown in the chromaticity model, the increase in the intensity of light increases with the temperature, while the decrease in the peak wavelength is as a result of the decrease in the temperature. This implies that the wavelength of the peak of the blackbody radiation curve will always decrease as a linear function of the increase in the temperature. The correlation is not evident in the model represented above since the intensity is depicted to increase with the fourth power of the temperature. This implies in the model depicted the nature of the peak wavelength change can be more evident if the plot is made to the fourth root of the intensity. 

The human eye that has a normal vision is considered to have three kinds of three cone cells that are sensitive to light, where they have peaks of spectral sensitivity in the short, middle and long wavelengths ( Bellia et al., 2011) . The short wavelengths range from 420-440nm, while the middle spectral sensitivity is achieved at 530nm-540nm. Moreover, the long spectral sensitivity is achieved at 560-580nm wavelengths. These kinds of cone cells underlie the perception of color in environments with medium and high brightness ( Hasegawa et al., 2015) . This means that in dim light, the color vision is diminished, while the monochromatic receptors that dominate the rod cells become effective. The model shows that there are three parameters that correspond to the levels of stimulus belonging to the three kinds of cone cells, which also explain the color sensation in human beings. 

Munsell Color Wheel 

The Munsell color wheel below consists of three independent dimensions that are depicted in the form of a cylinder in the X, Y, and Z plane as an irregular color solid. The hue is measured in terms of the degrees around the horizontal circles, while the chroma is an outward radial measure from the neutral or gray vertical axis. Consequently, the value is a vertical measure from black to white. The determination fo the spacing of colors along the said dimensions is carried out by measuring the human visual responses. It should be emphasized that in each dimension, the Munsell colors are nearer to perceptually uniform as one can make them, which means that the resultant shape would be irregular. an example of Munsell notation is that of the “Pigment Color System and Notation,” where he finds out that the desire of fitting a chosen contour such as a pyramid, cone, cylinder or cube coupled with improper tests has resulted in many distorted statements of color relations, where it is evident when physical measurements of pigment values and chromas are investigated, where no regular contour will serve. 

The hue circle was based on the conception that complementary colors having red at 12.00 0’clock position should be followed by orange, yellow, and green. This conception was based largely on the scientific principle of the visible spectrum ( Cochrane, 2014) . In the hue circle below, any three colors that are separated by 120 degrees form a complementary trio as depicted by the colors red, green, and blue. 

The color wheel takes a step further as it is segmented into units in which primary colors are ten units apart. The wheel shows that the red and yellow colors are separated by ten units and in between at the five units, one can easily find orange/yellow. The other ten units that are the separate yellow color from the green color in the when at five units between yellow and green is green/yellow. The circle goes on with the depiction of how the segmented units show that primary colors are ten units apart. Since he considered the color as a three-dimensional family, Munsell went ahead to depict the value and the chroma. 

Munsell considered the value or lightness of the color, where it varies along with the color solid from the black (0) at the bottom to the white (10) located at the top ( Hasegawa et al., 2015) . The wheel shows that the neutral grays are located along the vertical axes in the middle of black and white. On the other hand, the chroma is measured in a radial position from the center of each slice, where it is a representation of a color that is related to the saturation, while the lower chroma is less pure. The wheel does not depict an intrinsic upper limit to chroma. The wheel shows that each area of the color space has a different maximal chroma coordinates ( Bellia et al., 2011) . The best example is where the light yellow colors are shown to have considerably more potential chroma as compared to the light purples, which is a consequence of the nature of the eye and the physics of stimuli of the eye. The wheel depicts a wide range of possible chroma levels including the high 30s for the combinations between the hue and the value. 

The major setback is that it is not possible to make physical objects in colors having high values of chroma, while they cannot be reproduced by the current technological displays. This implies that the solid colors do not exceed the range of 8 ( Kirillova et al., 2015) . The color wheel is useful as it specifies the color of choice by listing the three numbers for the hue, value, and the chroma in an orderly manner. For example, a purple medium lightness and fairly saturated would be depicted as 5P 5/10, where 5p is the notation of the color in the middle of the purple hue band, while 5/ is the medium value or the lightness. Consequently, 10 is the chroma just as the digits on the watch are placed. 

Question #3: Project 

Background 

Architectural lighting design is critical in any building because it stipulates the interior lighting including electrical lighting as well as the natural lighting or both of the office rooms to serve human needs ( Muhamad et al., 2010) . The lighting design of abuilding depends on various factors which include the nature of human activities for which lighting is needed, the amount of light required in the room, the color of the light required because it affects the environment as a whole, and the effective lighting system to the user ( Arth et al., 2017) . Finally, lighting design for an office building depends on the distribution of light in the space to be lighted whether indoor or outdoor. The main idea of illuminating the office or lighting the room is to enhance a human to see clearly without discomfort.

This report is about the codes, regulations, guidelines, and best practices that are required for the illumination of an office building. The report has been prepared to support design efficiency, and quality control and provides the kind of information that the architectural designer will need to ensure effective design of lighting systems in the office building. The building with which the lighting design is needed was built in 1972 and it is a typical office building with the cast-in-place concrete frame, curtain wall system of the main floor, and the precast congregate panel skin with punched windows on the upper five floors. The dimension of the building includes a rectangular footprint 30X 42 meter in size and comprised of 6 by 6-meter bays ( Bellia et al., 2011) . Furthermore, all the elevations are uniform on all the sides. The building needs recapitalization because it requires complete renovation. This report, therefore, seeks to provide the guidelines and best practices for the architectural lighting design that would meet the client's requirements for LEED Gold certification, high level of energy efficiency, optimal workplace environment for office workers, increased penetration of daylight to interior spaces, and reduced operating costs. The report will include the design of electrical lighting to ensure that there are appropriate lighting quality and quantity in the building.

Office lightening design considerations 

The design is the science and the art of making things become more useful to mankind. Therefore, lighting design of office illuminance design is the application of lighting both electrical and natural/daylight to human spaces ( Hasegawa et al., 2015) . Like many other engineering professions, lighting design relies on the combination of particular scientific principles and guidelines, established standards and conventions and the number of aesthetics and other human factors employed in an artful manner ( Karlen, Spangler, & Benya, 2017) . Lightning design in the recent times struggles with two major aspects of efficiency and lighting quality. In all the lighting design the quality of light and energy efficiency are critical. Therefore, any lighting design work must put into consideration lighting efficiency and quality to the benefit of the client.

Lighting engineers or designers initially faced the problem of choosing between attractive and well-designed spaces and spacers that used a minimum of energy. Therefore, the pursuit of more energy efficient lighting domna5ed the greater part of the last decade enabling the designers to develop some important guidelines and codes that must be followed to ensure effective lighting of the office building to meet the human needs ( Karlen, Spangler, & Benya, 2017) . The advanced lighting guidelines codes and bests practices describe the technology that is needed to encourage the designers to provide quality of lighti8ng with reduced environmental impact. To enhance energy efficient and quality lighting, the illuminating engineering society of North America (IESNA) described the best guidelines and practices that would promote proper interior and exterior lighting for all kinds of buildings. The recommended procedures for lighting design s are described in section 3.3.4.

Lighting in the workplace best practices 

Several lighting aspects must be considered to ensure that there is suitable and sufficient lighting in the office or the workplace. They include but not limited to lighting design; type of work; the work environment; health aspects; personal requirements; lighting replacement, maintenance or disposal; and emergency lighting. In designing the illuminance for the office building for the client, our company intends to follow the needed guidelines, lighting design codes and bests practice ensuring that all interior and exterior lighting contain lamps, luminance, and efficient control systems ( Karlen, Spangler, & Benya, 2017) .

Interior and exterior installations 

The amount of lighting affects the ability of people to see. Thus, the finer the details the higher the illuminance is needed. It is required that both the inner and the exterior lighting meet the required reasonable and uniform illuminance in all the appropriate working places ( Muhamad et al., 2010) . The illuminance in any of a given task placer musts is uniform to enhance good vision. The CIBSE code of lighting gives further information about the uniformity of illuminance. The lighting design must take into account the effects of the shadows cast. The light sources must be positioned incorrect places to minimize the effects of shadows. For example, it is a bad practice to illuminate machinery from below because the shadows may lead to confusions and lead to an accident ( Karlen, Spangler, & Benya, 2017) . Typically, the type of lighting installations needed or chosen depends on various factors which may include the following the suitability for use, the size of the area covered, the purpose of the light, the physical constraints of space and use safety.

Interior lighting guidelines 

Lighting guidelines 

Interior lightening is divided into three main categories which include general, localized, and local. General lightening normally provides uniform illumination in the entire working place/space and does not provide any limitation of the work. Localized lighting offers different levels of illumination in various parts of the same working place. This lighting category aligns the level of illuminations with the needs of particular tasks ( Bellia et al., 2011) . Local lighting is usually the lighting systems that comprise of the background lighting and luminaire near the actual working place. Local lighting category is used in illuminating the workplace when a higher level of illumination is needed, flexible dictatorial lighting is required, general lighting is impossible to install due to the layout of the working area.

Lighting Quantity 

The determination of the lighting level is critical. It is important for the lighting designer to choose levels of lighting that is needed for appropriate lighting ( Hasegawa et al., 2015) . The recommendations for the quantity of light are provided with the assumption that the viewer is day adapted ( Muhamad et al., 2010) . Notably, the human eye is highly adaptive so that the illumination level is not critical. Increasing the illumination levels by generally 00 percent by design or by addition of daylight will make small improvements in visual performance. The factors to take into consideration when determining the quantity of light in the office include the adaptation levels of the viewer, the age of the viewer because the natural aging of the human eye reduces the visual acuity and increases sensitivity to glare ( Arth et al., 2017) . Therefore higher levels of light levels help in visual acuity when the glare is controlled. For seniors, it is advisable to choose light levels at the top level and lower levels for the young and energetic people ( Karlen, Spangler, & Benya, 2017) . Furthermore, the visual size of the task is needed to be considered. Very small tasks may require higher lighting levels while larger tasks require lower levels of light. The current project will require medium lighting levels because the lighting will be needed for normal office lighting. The federal government used the offices for normal daily operations and administration that requires general lighting only.

Finally, the quantity of lighting depends on the interaction of tasks in which jobs involving computers and paperwork need different categories of lighting or dimming controls to attain the acceptable compromise. The advanced guideline for the light level section includes the design of the lighting systems that are dynamic rather than a static model of vision and natural light/ daylight. It is advisable for the designer to vary the electric light to achieve potential energy savings and other beneficial effects ( Bellia, Bisegna, & Spada, 2011) . The ability to modulate the lighting levels, proper electric light can be used all the time keeping the necessary minimum light level and thus the necessary lighting energy consumption. For example, an office facing a south-facing window may require no electric light because of sufficient daylight energy. The office exceeds the IESNA recommended 30 foot-candles for the average paperwork. However, on a dark cloudy day and sunset, it is advisable to maintain the task light normal through electric lighting ( Laughton, & Say, 2013) . Towards the evening a lower task light levels may be needed and by the time people arrive to clean the offices. Most importantly, when the office is vacant it is advisable to keep the electric light turned off to maintain efficiency.

Illumination level needed based on the lighting spectrum must comply with particular conditions under which the light source spectrum is needed to be considered. The first thing the lighting designer must consider is the optics of human vision. The diameter of the eye's pupil is set by the response of the rods at typical interior light levels. When designing the illuminance level of the interior light level, it is vital to consider Berman's ratios called the Scotopic/Photopic ratios or the S/P ratios. The ratios are independent of the light levels and show the property of light or lamp spectrum and the extent to which a lamp favors the scotopic effects. For the office that the company needs to illuminate, the designer should consider the following scotopic/photopic ratio for indoor lighting Application ( Karlen, Spangler, & Benya, 2017) .

Apparently, as an advanced illumination guideline, S/P ratio can be sued to determine the relative sense of brightness from various sources and in particular, situations to predict acuity and the depth of the field benefits ( Cochrane, 2014) . Moreover, the lighting designer should consider using the lumen correction factor of between 1.2 and 1.4 for the current mercury-arc white light sources as compared to high-pressure sodium light sources.

Quality of Lighting 

Lighting greatly affects human reactions to the environment. In building illumination, human reaction range from emotional responses and a dramatic beauty of an illuminated landmark. It is therefore important for the illumination designer to consider important aspects of light quality to ensure that the building is light properly to sever the needs of office use. Architectural lighting is known for its ability to intuitively and artfully provide high-quality lighting for office tasks. Lighting quality plays a dominant role in lighting quantity ( Muhamad et al, 2010) . The design procedure provided in the night edition of the IESNA lighting handbook is based on lighting quality. Therefore, it is critical for the designers work hard and design the interior and exterior lighting that is capable of meeting the lighting quality. Achieving the lighting quality needed is not an easy task because often designers are faced with the problem of achieving good lighting because of various obstacles ( Hasegawa et al., 2015) . Therefore, during design, it is critical for designers to categorize lighting into three main quality categories. The categories include bad lighting in which lighting systems suffer from a quality defect, indifference lighting in which the lighting systems suffer from quality defects, and good lighting in which lighting is technically corrected and meets the needed of the viewer ( Kirillova et al., 2015) . The distribution of the lighting in the office musts meets the needed of the office. In particular, ambient requirements are needed. In this case, the light designer can design ambient lighting that illuminates the majority of the space to about 1/3 the task illumination level. In offices where the spaces are subdivided, it is important to ensure that the effects of partition are considered. Typically, office partitions reduce the average ambient illumination by 30-35%.

Therefore, ambient lighting design that provides nearly 30 foot-candles average illumination in an empty room is recommended ( Laughton, & Say, 2013) . The final guideline for the illumination of the office is the use of lighting that meets the requirements of the task. It is critical that the lighting designer provide task lighting that is under control all the time. Installing the task requirement lighting is vital because every work has a particular degree of specularity. Therefore, the ability to see the work is affected by the direction of the incident light.

Exterior Lighting design 

The exterior lighting is also critical for the building because it also adds to the room illuminance. Typically, the exterior lighting will be installed such that it achieves uniform illuminance on all the relevant work areas, and avoid glare to the users of the officer and the surrounding people ( Muhamad et al., 2010) . The department of environment, food and rural affairs and CIBSE provide further guidelines on how to design lighting that does not affect others and the surrounding environment. When designing the exterior lighting, the designer musts ensure that the lighting recommendations are consistent with the lighting suggested in the lighting manual. It is recommended to place the luminaries close together to avoid excessive contrast in illuminance ( Laughton, & Say, 2013) . This is usually important in security lighting where the variation of light levels may cause security threats/ risks.

Furthermore, the fact that the lighting space is large, the lighting design chosen will be based on the degree of obstruction, and whether the luminaries are needed on the horizontal or the vertical planes. On lighting the periphery of the lighting, the wall-mounted fittings must be used ( Muhamad et al., 2010) . They must are placed or fitted to ensure that uniformity and glare are reduced for people entering or leaving the building. It is critical for the building to have an emergency lighting system. Emergency lighting systems installations should be made similar to permanent lighting systems, but additional strength should be provided for the emergency lighting due to wear and tear of the equipment.

Lamps and luminaires 

In the market, there is a wide range of commercially available lamps. Different lamps provide different degrees of light and lighting properties ( Kim et al., 2017) . Therefore, the choice of lamps must depend on factors such as the type of workplace and the luminous efficiency. For this project, the lamps and luminaires must support and protect the light source, provide safe electrical connection, safe for installation, and remove the harmful level of radiation ( Muhamad et al., 2010) . The lighting designer musts use the guideline on luminaire types to ensure that the correct lamps are selected because each luminaire is designed for a particular light or range of lights.

Design considerations for effective lighting 

For energy efficient lighting, the designer musts use efficacious sources in many applications as possible. Color appearance is critical in office lighting, and it has been a significant long-term issue in office lighting design ( Hasegawa et al., 2015) . The most crucial aspect of light is to design energy efficient installations that can either be full-size fluorescent, compact fluorescent and HID lamps to create spaces balanced at differing temperatures to eliminate incandescent bulbs. Light fixtures come in a variety of styles and various functions ( Laughton, & Say, 2013) . The most critical light fixture is the luminous efficacy which means the amount of light emanating from there fixture per energy. It is measured in lumen per watt. The table below provides the preferred color temperature ranges.

Design Calculations 

Question1; 

To determine the number of fixtures, the formula used is: 

For question 1; the CU= 0.7, LLD= 30% for the select 54 W lamp; LDD= 0.92; and BF=1.02

Number of fixtures= 4.5X1.2 X150/(2X 0.75X 0.71X0.3X 0.92X 1.02)= 810/0.2998=270

The number of fixtures is, therefore, equal to 270 given the specifications provided in the equation. The coefficients are selected based on the lamps selected for installation in the building.

Question 2: 

Determination of illuminance is needed when designing the correct lighting for a workplace. Normally, the lumen formula is used to calculate the illuminance. Therefore, for the provides specifications, the illuminance can be given by the formula below:

Whereby;

LLD= Lamp Lumen Depreciation

LDD=Luminaire Dirt Depreciation

CU=Coefficient of Utilization

BF=Ballast Factor

Replacing the values in the formula provided; the illuminance will be given by:

Illuminance (Lux)= (10X2X 0.915X 0.71X 0.3X 0.92X1.02) ÷ (3.6X 4.5) = 3.6577/16 = 0.2286

Question 3 

The total light loss for the first scenario is given as below:

TLL=LLDXLDDXBF

=0.71X0.92X1.02

=0.6662

The total lighting loss for both scenarios is the same because the building is the same and the dimensions are chosen are the same. The rooms have similar partitions and the illumination is basically the same due to the selections of the same lamp types.

Question 4: 

The room cavity ratio is calculated by the formula;

For the first scenario

RCR= 5(3.0) (4.5+1.2)÷ (4.5X1.2) =85.5/5.5p 1.53

For the second scenario; the height of room cavity is 4.5 m, length of the room is 7.2 m and width is 3.6 m.

Therefore, RCR= 5(4.5)(10.8)÷(3.6x7.2) = 0.938

The ceiling cavity ratio for the scenario is given as follows:

Whereby:

Hcc= 0.915, L=7.2 and W= 3.6 

CCR= (0.915X 10.8)/ 25.92 = 0.38 

from the calculations, it is clear that one cannot use a particular ratio because of the differences in the building dimensions. The ratios depend on the space, and the bigger space, the higher the ratio. 

I t should be noted that the report has provide d the best practices, guidelines, and codes that are needed for an office illuminance. The lighting designer must be keen on the selection of the fittings and utilizing daylight during light design for a building ( Dubail et al., 2016) . T he most impost aspects that must be put into considerations include the lighting quality and quantity. Proper design requires that the designer considers cost because it dramatically affects the budget for housing illuminations. For the current project, the company will ensure it follows all the stipulated lighting principles and guidelines.

Next Question: The assignment 

Accommodating Margaret 

Margret’s situation is such that she has problems with tolerance to bright light. In her case, it is possible to modify or change the light fixtures and furnishing configuration, but it is not possible to change the ceiling height. The lighting system in her room involves the use of luminaires that combine direct light on the work surfaces, with an indirect light focused towards the ceiling ( Hasegawa et al., 2015) . In this case, a varying and appropriate concentration of light is distributed throughout her working station. There should be vertical light on the wall, 300lux, which provides ambient light. Indirect light on the ceiling, 300lx, also provides her with good ambient light for better performance. Direct light from the luminaires will give her 50lx on the table, to ensure that she does not have problems with visualization. Since uniformity of light is important for reading, the practical and more practical tasks will require higher sensitivities but those that do not exceed 150lux. 

Cylindrical luminance will also be an effective tool for Margaret as it affects visual communication and the ability to interpret facts, events, and objects. The standard will require luminance of 150lux since her room demands good visual communication with the visitors. The light should be adjusted after tasks. In this case, the light rendering properties of the light source will be significant while working with the design and the color. The color rendering, in general, should not be not less than Ra50, even though for photography, the value may be increased to Ra 60. 

Considering her problem with the left eye, the luminaires must be suitable for work, where the designer should avoid glare and veiling reflections. Her condition requires that she needs less light to perform the same task as a person with normal vision ( Karlen et al., 2017) . The designer may also find the need of using the Fagerhult’s Wireless e-Sense connect lighting control system. She will also need a daylight and presence detector in the workplace to adjust the lighting for all areas of the space. Once she leaves the room, the light switches off and resets automatically. 

In the determination of the units of light levels of luminance for Margret, it is vital to consider that: 

1 lux = 1 lumen/ sq meter = 0.0001 phot = 0.0929 foot candle (ftcd,fcd) 

Figure 5: Design of Margaret’s Office 

Calculations: 

Consider that Illuminance= (Lumen per lamp x Light loss x utilization)/Area 

= (10 x 0.85 x 0.69)/(3 x 3.36) 

= 0.58 

The total voltage of the fixtures = Number of lamps x each of the lamp’s watts 

= 2 x 16 = 32 

The Lumen per fixture = Lumen per watt x each fixture watt 

= 10 x 32 = 230 

The required number of fixtures = (Required lux x room area)/(LLF X UF X Lumen per fixture) 

= (150 x 3.0 x 3.6)x (0.85 x 0.69 x 3.6) 

= 9 fixtures 

The transverse spacing ebtween the fixtures = width of the the room/ number of fixtures 

= 3.6/9 = 0.4 meters 

Design for daylight and Electric Illumination for the Office Complex 

The Daylight Plan 

The form and construction of faced systems are influential on the consumption of energy of a building and the level of comfort of the occupants ( Hasegawa et al., 2015) . The plan is to come up with a double window system (DWS) that is an energy-efficient system, where a cavity between the inner and the outer layers serve the purpose of the provision of natural ventilation, control of solar radiation, while it also acts as an insulator ( Ito, 2016) . The DWS is a faced with high levels of effectiveness in reduction of energy consumed in heating and cooling. The double-skin faced defined by the DWS will also offer better thermal comfort in winter while lowering the thermal amplitude in summer. 

The double-skin facades have an advantage over the single-skin facades as they reduce the consumption of energy, especially during the hot and temperate seasons, while they do not require any form of additional energy input. During the cold seasons, there will be a system of proper shading and natural ventilation devices in a bid to reduce the levels of energy consumption ( Karlen et al., 2017). This will mean that the operations of the double-skin façade will influence the general energy performance of the building. There will also be a greenhouse effect caused by the cavity, which will increase the heat stress to the internal space, where appropriate natural ventilation control will be a requirement. The geometry of the DWS is as shown below: 

Figure 5: Geometry of the DWS 

Figure 6: Window settings and natural ventilation 

The plan of the building includes 70% open office landscape, 15% private offices and meeting rooms, and 15% common space. Since the office will be open, it will have a view both in and out of the building. It is also evident that 80% of the occupied areas in the building will have some form of daylight without glare or excessive heat gain. The Daylight Factor will be represented by the ratio between the level of illumination of a specified indoor point and the outdoor horizontal illumination level. The daylight factor for this plan is very low in the living room especially when the device is implemented in the DWS. The ration of the sensor grid when the daylight factor is more than 2 is 0% for DWS-1 with a shading device. In this plan, the shading device is set to 45 0 to enable reflection of the solar radiation outward and to reduce the cooling load from increasing as a result of the solar heat gain (Dubail et al., 2016) . The results of the daylight factor simulation depict that the double-layered window systems such as the DWS may impair visualization during the cooling period with the selected shading device. The table below shows the simulation of the daylight factor for this plan with the specific shading condition.

Table 1: Simulation of the Daylight Factor

Architectural and Landscaping Elements 

The interior of the building should be embedded with a decorative layer. The best way of thinking about decorative lighting is the jewelry of architecture. Decorative lighting plays an important role in the interior design and the themed environments. The lighting is known to provide a desirable eye-level glow that is missing from the spaces that are illuminated by light from the ceiling ( Karlen et al., 2017) . The ambient layer will be vital as it will provide the background lighting that will help in the creation of the mood of the space. The ambient lighting will allow for visual recognition and navigation through space. It should be emphasized that the ambient light level in the space should be lower than the focal light level, where the contrast between the focal and ambient light will automatically be high and space will appear to be more dramatic. 

Figure 6: Example of ambient lighting with low-contrast 

Glazing/Wall Area 

Glazing walls will be used as they have the ability to let natural light into the facility. They will help increase the exposure to natural light. The complex office will be made of framed glass swinging doors that are meant to provide the aesthetic advantages of glazing with additional structural and acoustical performance of the full framing. The specifications of the glazing will be 1-3/4 by 4-1/8 inch metal channels at the floor, ceiling, and walls, which will dampen the system of sound transmission and add the structural definition without the impediment of sightedness ( Karlen et al., 2017) . The full framing will also accommodate uneven existing floors. The architectural finishes will be defined by unframed glass partitions that will have swinging and sliding doors with simple elegant fronts. The fronts will have extended transparent slightlinlines. The sliding door will work well especially when space is limited. There will also be a sleep top track and small guide at the sill that will allow for a smooth transition between the office and the corridor. 

The Anterior Lighting Plan 

Instead of the standard switches or dimers at the anterior section of the office, the designer will consider using the preset scene controllers. The basic scene controllers will fit within four-gang recessed boxes and will be viable for controlling up to six zones of light ( Hasegawa et al., 2015) . The system of lighting at the anterior section will be similar to that of the car radio as it will have the capability of remembering the present in such a way that it will be recalled repeatedly without the requirement of manual adjustments. The individual zones will be set at different levels as required and memorized as a scene. 

The axial spacing at the anterior will be determined by the quotient between the anterior length of the room and the number of the fixture in each row. 

= Length of the room/number of fixtures in each row 

= 6.0m/5.0 = 1.2 fixtures 

Lighting Controls 

The lighting controls for the various spaces will be integrated into the day-lighting plan. The daylight available in space will be evaluated in such a way that the opportunities of reducing the lighting will be realized early in the stage processes. In this case, the energy savings will be captured in case fixtures are reduced or controlled properly ( Karlen et al., 2017) . The daylight will be used to reveal true colors in spaces, while the building fenestrations will provide views and ventilation. Daylight will be considered to create a positive effect on people through the reduction of stress as it will encourage positive attitudes while increasing productivity. In addition, the contribution of the sun and daylight will require control to reduce glare and unwanted heat gain. 

Light Sources 

Incandescent 

The incandescent light sources can be in open office areas as they have the feature of immobility. In this case, lamps can be operated at less than full intensity, which is an energy-saving or a mood-creating model. The lamps allow for the possibility of dimming, where the user can control the amount of light that is required. 

Fluorescent 

Fluorescent light sources are best suited for private offices as they have the capability of converting more energy input power into visible light as compared to the incandescent lamps. This implies that even of the private office is enclosed; the lamps can emit light without overheating the room, which increases the comfort of the users. 

High-Pressure Sodium 

The high-pressure sodium can be used in the park and in walkways. This is because such sources of light have high efficacy levels, where they exhibit high levels of lumens per watt. Having a high efficacy does not take into consideration the directionality of the lamp, which implies that the light source can serve users from all angles. 

Metal Halide 

The metal halide lamps can be used in private offices since they have the ability to provide the crisp white light in a variety of different color temperatures that can accommodate the needs of the user ( Karlen et al., 2017) . The high-pressure sodium and mercury lamps are considered to have limitations in their color and the quality of light that they produce, which makes them excluded from use in places such as the parking area and walkways. 

Induction 

Induction light sources are commonly used in the parking areas and in walkways. They are considered to be having multiple uses as they come in three basic shape types including the line sources, the point sources, and the area sources. Each of this shape has the ability of radiating light differently and this causes unique effects especially in the dark. 

LED 

The LED light sources can be used in walkways as traffic lamps as they offer capabilities such as robustness, smaller size, and faster switching. They are considered to consume lower amounts of energy as compared to the incandescent sources. Unlike the laser, the color of the LED lamps is neither coherent nor monochromatic, while the spectrum of the light that they produce is narrow with the human vision ( Karlen et al., 2017) . This means that the light from a simply LED diode can be considered as functionally monochromatic. 

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