Module 2: Lighting Design Principles PDF

Module 2: Artificial Illumination and Daylighting Topic 2: Lighting Design Principles The significance of lighting in building architectural. Lighting is the foundation of architectural buildings. It can change the perception of space, the shape, textures of materials and improve their aesthetic fe...

Module 2: Artificial Illumination and Daylighting Topic 2: Lighting Design Principles The significance of lighting in building architectural. Lighting is the foundation of architectural buildings. It can change the perception of space, the shape, textures of materials and improve their aesthetic features. It also plays an important role in ensuring the comfortability of occupants. When it comes to artificial lighting in architectural design, they are commonly planned at the later stages when the design is completed. There is no problem implementing artificial lighting ideas this late. However, it also means that the design is far from its ideal. Lighting Design “Design” is the science and art of making things useful to humankind; and lighting design is the application of lighting̲--including daylight when it is specifically used as a source of lighting–to human spaces. Like architecture, engineering and other design professions, lighting design relies on a combination of specific scientific principles, established standards and conventions, and a number of aesthetic, cultural and human factors applied in an artful manner. Basic Lighting Analysis Lighting Fundamentals To choose the best energy-efficient lighting options for your home, office etc., you should understand basic lighting principles and terms. Light Quantity Illumination The distribution of light on a horizontal surface. The purpose of all lighting is to produce illumination. Lumen A lumen is a measure of visible light energy. As reference, a 100-watt incandescent lamp emits about 1600 lumens. Watts Watts are a measure of energy consumption. When we pay our electric bill, we pay for the number of watts we use. A 60-watt bulb consumes 60 watts of energy. Footcandle A measurement of the intensity of illumination. A footcandle is the illumination produced by one lumen distributed over a 1-square-foot area. For most home and office work, 30– 50 footcandles of illumination is sufficient. For detailed work, 200 footcandles of illumination or more allows more accuracy and less eyestrain. For simply finding one's way around at night, 5–20 footcandles may be sufficient. Quantity of Illumination Light Output The most common measure of light output (or luminous flux) is the lumen. Light sources are labeled with an output rating in lumens. For example, a T12 40-watt fluorescent lamp may have a rating of 3050 lumens. Similarly, a light fixture's output can be expressed in lumens. As lamps and fixtures age and become dirty, their lumen output decreases (i.e., lumen depreciation occurs). Most lamp ratings are based on initial lumens (i.e., when the lamp is new). Light Level Light intensity measured on a plane at a specific location is called illuminance. Illuminance is measured in footcandles, which are work plane lumens per square foot. You can measure illuminance using a light meter located on the work surface where tasks are performed. Using simple arithmetic and manufacturers' photometric data, you can predict illuminance for a defined space. (Lux is the metric unit for illuminance, measured in lumens per square meter. To convert footcandles to lux, multiply footcandles by 10.764.) Brightness Another measurement of light is luminance, sometimes called brightness. This measures light "leaving" a surface in a particular direction, and considers the illuminance on the surface and the reflectance of the surface. The human eye does not see illuminance; it sees luminance. Therefore, the amount of light delivered into the space and the reflectance of the surfaces in the space affects your ability to see. Light Quality Glare The excessive brightness from a direct light source that makes it difficult to see what one wishes to see. A bright object in front of a dark background usually will cause glare. Bright lights reflecting off a television or computer screen or even a printed page produces glare. Intense light sources -- such as bright incandescent lamps -- are likely to produce more direct glare than large fluorescent lamps. However, glare is primarily the result of relative placement of light sources and the objects being viewed. Color Temperature The color of the light source. By convention, yellow-red colors (like the flames of a fire) are considered warm, and blue-green colors (like light from an overcast sky) are considered cool. Color temperature is measured in Kelvin (K) temperature. Confusingly, higher Kelvin temperatures (3600–5500 K) are what we consider cool and lower color temperatures (2700–3000 K) are considered warm. Cool light is preferred for visual tasks because it produces higher contrast than warm light. Warm light is preferred for living spaces because it is more flattering to skin tones and clothing. A color temperature of 2700–3600 K is generally recommended for most indoor general and task lighting applications. Color Rendition Color quality, or how colors appear when illuminated by a light source. Color rendition is generally considered to be a more important lighting quality than color temperature. Most objects are not a single color, but a combination of many colors, and certain light sources may change the apparent color of an object. The Color Rendering Index (CRI) is a 1–100 scale that measures a light source's ability to render colors the same way sunlight does. A light source with a CRI of 80 or higher is considered acceptable for most indoor residential applications. Light Uses Ambient Lighting Provides general illumination indoors for daily activities, and outdoors for safety and security. Task Lighting Facilitates particular tasks that require more light than is needed for general illumination, such as under-counter kitchen lights, table lamps, or bathroom mirror lights. Accent Lighting Draws attention to special features or enhances the aesthetic qualities of an indoor or outdoor environment. Energy Consumption Efficacy The ratio of light produced to energy consumed. It's measured as the number of lumens produced divided by the rate of electricity consumption (lumens per watt). Lumens to Watts Conversion Chart Lumens Incandescent Watts Halogen Watts LED Watts 100 7 6 2 375 25 20 4 450 30 25 5 800 60 45 9 1100 75 60 12 1600 100 90 17 2600 150 145 27 3000 200 175 32 Determining Target Light Levels The appropriate type and quantity of lamps and light fixtures may be selected based on the following:  fixture efficiency  lamp lumen output   the reflectance of surrounding surfaces the effects of light losses from lamp lumen depreciation and dirt accumulation  room size and shape  availability of natural light (daylight) 8 Lighting Design Principles Lighting can be simple or part of your design plan. Lighting can also support your goals of energy efficiency and saving money. 1. Focus your effort on rooms used most. Improving the lighting in these rooms will make a lot of difference. 2. Replace existing fixtures. Most rooms have incandescent or fluorescent fixtures. Replace them with dedicated, LED bulbs. 3. Layer lighting for maximum impact. To produce dramatic effects, design ambient, task and accent lighting. Ambient lighting provides general room illumination and may reduce the need for additional portable lighting. Task lighting helps occupants see better where they need it. Accent lighting adds sparkle by focusing on an architectural detail such as a fireplace or on photos or artwork. 4. Consider the room's function and form. No matter where you start, consider which activities are most important for the room. 5. Use concealed light sources. Occupants will notice the illuminated floors, walls and ceiling of the room instead of the light bulbs. Concealed light sources help eliminate direct glare from lamps. 6. Use LED bulbs. LED lights produce the same amount of light quality and light output as traditional fluorescent and incandescent bulbs but consume only a fraction of the power. Statistically speaking, LED lighting consumes 18% electricity compared to conventional fluorescent lamps and up to 85% less lighting when compared to traditional incandescent light bulbs. Thus, offering massive energy savings.  7. Limit the number of different light sources. Use only three: 5-, 9- and 15-watts LED lights. This makes it easier for occupants to replace the lamps. 8. Consider controls. Controls such as photo sensors, occupancy sensors, dimmers and remote controls may help to reduce energy by ensuring that lights are only used when needed. 10 Lighting Design Considerations 1. Light Distribution and Brightness Daylight is a fantastic resource, but think about how it will interact with the artificial light inside your building. One study conducted by Alan Hedge of Cornell showed that workers in office environments with optimized natural light saw an 84% decrease in symptoms of eyestrain, blurred vision and headaches. These are all symptoms that detract from productivity. Windows are definitely a worthwhile design choice, but you also have to account for the adverse effects of natural light. These include:  Varying amounts of cloud cover or inclement weather that reduce the amount of light available  Unwanted heat driving up the temperature in certain areas, causing inconsistency throughout the office and “thermostat wars”  Glare on computer screens or workspaces, making it difficult or uncomfortable to get work done One approach is to install optimized windows that can adjust tint and adapt to reduce glare. These windows offer the satisfaction and productivity benefits of natural light while combating the issues that make it challenging to use in an office space. 2. Conservation of Energy Many older lighting design types, like incandescent and fluorescent, consume comparatively huge amounts of energy. In traditional incandescent bulbs, 90% of the energy they emit is given off as heat, making them a very wasteful option. Changing bulb types to more efficient LEDs can be one of the best ways to save energy, which is good for both the environment and your bottom line. LED stands for light-emitting diodes, and they work through a process called electroluminescence, which generates light as an electric current passe through a semiconductor material. LEDs have several benefits that make them the ideal choice for an office environment. They are:   More efficient: LEDs can use anywhere from 25 to 80% less energy than their incandescent counterparts. These savings offer significant reductions in operational costs. LED bulbs last longer than traditional incandescent bulbs. The Department of Energy reports that a 60W incandescent bulb will last for approximately 1,000 hours. You can expect a similarly-bright 12W LED bulb to last around 25,000 hours. LED light bulb uses just seven to ten watts while a fluorescent light bulb consumes 16-20 watts, an incandescent light bulb will use 60 watts typically and cost about 0.6 cents an hour to run, according to the energy use chart.  Longer lasting: LED lights also save money through replacements. They can last up to 25 times longer than traditional incandescent, which also reduces maintenance needs.  Cooler: With a lower heat output, these lights are safer and help you maintain your desired temperature without added warmth.  Dimmable: Colors are varied and flexible, allowing for lighting that can adapt to your needs. The color rendition of LED bulbs is excellent, so your office can look just how you intended. 3. The Appearance of the Space and Luminaires Lighting design types should be aesthetically pleasing and match the feel of the office space. Luminaires refer to different light fixtures and include recessed fixtures, direct and indirect pendants, under-cabinet lighting, wall wash lights, sconces, and task lighting, among others. Effective luminaire combinations can create expertly lit areas. 4. Glare There are a few different types of glares, including direct and reflective glares. Direct glare refers to the view of a light source, typically in high contrast to its surroundings. Lamps and sunlight can cause it. Reflective glare is a little more challenging to deal with, as it comes from items we work with, like glossy paper, desks, and computer screens. Reflective glare means you’ll need to consider the surface colors in the room as well as the diffusion of the light sources. Matte walls and surfaces may help to reduce reflection glare, while indirect lighting can help reduce glare from the lights themselves. 5. The Appearance of Color If you ask people what color a lightbulb emits, many of them will say “white,” but there is actually much more to the color of light than that. Warm colors, like reddish hues, are lower in temperatures, and cool colors, such as blue, are higher in temperature. Below is the typical range of color temperatures.  Warm: 2700K to 3500K. This range would include the color of a sunset.  Neutral: Around 4000K.  Cool: Above 4700K. This color resembles a bright, sunny day.  These different color temperatures can have varying physiological effects on people. Warm lights, for instance, are cozier, and often make people eat more, so they are used in restaurants, but could also work well in a break room or lobby. Cool colors, on the other hand, mimic natural daylight more closely. 6. Lighting Control and Flexibility With a comprehensive lighting system, you may need a little more than a light switch to control them all, especially if you are using smart options with sensors or automatic responses. Many modern systems can work wirelessly, which is especially beneficial for retrofitting or for buildings with hard-to-wire areas. Wireless controls can be placed almost anywhere and moved or expanded as needed. One common lighting control method is to install occupancy sensors that will automatically turn on your lights when employees are present. This approach saves energy since it turns off when not in use and even offers hands-free activation. 7. Lighting of Faces Lights influence more than just the bright parts of an office — they also affect the dark parts. Some styles of lighting increase the presence of shadows and offer themselves to dramatic lighting. Blending direct and indirect light can offer even ambient lighting with direct highlights to certain areas of the room, like a presentation space. Some places in an office need more definition than others. In a meeting, for example, it helps to clearly see the face of the person presenting and the information they need to show you. In museums, points of interest may receive up to 10 times the ambient light level to highlight the item. 8. Cost of Implementation While you consider overhauling an entire lighting system, the associated costs surely haven’t escaped your mind. Some of the costs involved include:  Equipment  Installation  Design  Maintenance  Energy  Environment 9. Installation The installation process can vary widely, but one thing is for sure — if you opt to organize your lighting system yourself, you’ll need licensed electrician and maybe a contractor too. 10. Maintenance To get the most out of your light system, you’ll need to maintain it properly. For some light options, maintenance is no more complicated than taking out a bulb and replacing it once it has become dim or gone out. You can cut down on maintenance costs by purchasing equipment that requires less work to keep up with, like LED bulbs, which have longer lifespans.