Discuss About The Mechanical Electrical Equipment Buildings.
Describe how the differences between the rods and cones in the human eye affect our vision. Explain how these differences affect lighting design for different tasks.
In human eye there are two types of receptors namely rods and cones. Rods are involved at scotopic vision (low level) that’s why we see everything in grey shades at night. They have low vision acuity and they are not able to see color. Cones are involved at photopic vision. They have high vision acuity. Cones are active for fine detailed work. Cones are of three types S cones, M-cones, L-cones. Rods are more photo pigment while cones are less. Rods have long integration time and cones have short integration time (Guyton, Arthur & Hall 2006).
All three types of photoreceptors in retina contribute in response of the eye at high level of light (daytime). All the tasks like wood machining, general office work, and casual seeing require high level of light. Mostly in all these tasks contribute cone receptors. For very fine details works like jewelry making, watch making and assembling of electronics require high level of light. Rods, cones or mixture of rods and cones involve in visual performance of driving at night.
Acceptable light levels are dependent on the nature of the task being undertaken. List five distinct considerations that may influence the required light level in a workplace situation. Explain these factors with diagrams
Adequate lighting is very important at work place for the worker. Sufficient lighting is responsive for the good production. There are many factors that should be considered for the required light level in a workplace.
Luminance is the factor that require for level of light. Luminance is the intensity of the light on the surface. Factors affecting luminance are distance from the light source. The light is decreases as the square of distance. Distance does not affect intensity of light.
Orientation is the second factor to be considers. When the surface is tilted away from the source of light, the larger area is covered by the light. If the plane is inclined to the direction of light, the intensity of light decreases.
Flux distribution of the luminiare is the other factor to be considered. The level of light on the workplace is affected by the relative proportion of upward and downward light. High proportion of downward light increases the illumination on the workplace.( McGuinness, William & Stein 1955).
Configuration of the room is other important factor. Small spaces reflected back more light on the surfaces of walls while large rooms have little bounce lighting.
Reflectance of the room surfaces is factor to be considered while achieving required level of light. The surrounding surfaces affect the amount of light that falls on the light. Ceiling should be of light color to spread more light.
Explain how you would decide what light levels are required on a work surface for particular workplaces. Give at least five examples of different visual tasks and state the range of illuminance that is acceptable for that task
There is some factor that should be considered to gain required level of light on the different work spaces. Luminous flux, intensity, illuminous and cd/m2 are major consideration for required level of work (McMullan, Randall 2002).
The light spread all over the direction by a particular light source is known as luminous flux. The quantity of the light falling on the surface is known as illuminous. Working spaces can be too bright and too low, and these are dependent on the task to be done. Fine detailed works like jewelry making, watch making and electronic assembling require bright work spaces. For casual office work, cable tunnel work normal natural light is required (Gordon, Gary & Nuckolls 1995).
Characteristics of task
Wire works in tunnel,
Fine details are not required
Office works, gardening, shops.
Interior with adequate demand for vision.
Electronics works, drawing in offices.
Interior with moderate demand for vision.
Fine detailing assembling of electronics, drawing and drafting, super marts
Interior with high demand for vision.
Hand sewing, very preside assembling, assembling of tiny mechanism.
Interior with demand of highest level for vision.
List at least five important factors that affect the amount of natural light falling on a work surface inside a building. Using diagrams explain how this works.
Daylight inside the building is very important according to physiologically and psychologically. Natural light is more effective source of light than the artificial light. Fenestration is the collective term of the windows in building. Natural light is entered inside the building through windows. The more the windows the more natural light enters the building. Big windows in building provide deep natural light penetration. More natural light is achieved by providing many windows. Fenestration impacts on the ease of workers; fresh air enters the building and ventilation of air. The quality and amount of natural light inside the building is affected by many factors. The natural light depends on the brightness of sky. The quantity of light in building also depends on the shape, size and position of the windows in the building. The light after external obstruction arrives at a point in a room is externally reflected component. The light after reflecting from internal surfaces arrives the point is known as internally reflected component (Rea 2000).
The position of sun changes the quantity of natural light. There are two types of variation according to the sun, daily variation and seasonal variations. At sunset and sunrise, day light is low while at solar noon, solar illumination is high. According to the seasons, sun changes its path. In the southern hemisphere, the sun rises and sets;
To the south in summer
Name and describe the two different causes of glare which may cause disability or discomfort depending on the magnitude of the effect. With diagrams describe what measures can be used to reduce glare in buildings
The difficulty in seeing due to the excessive and uncontrolled light is known as glare. There are generally two type glare, discomfort glare and disability glare. Intense light sources reduced the visibility at workspace; this glare is known as disability glare. Excessive bright sources develops the sensation of nuisance; known as discomfort glare.
Glare can be reduced by reducing the luminance of the source. The brightness of the background light can be reduced by tilting the windows and screening lights. Shiny surfaces cause glare so it should be avoided.
As luminance of the surrounding area increases, glare is decreases. Light color paints should be used on the surfaces around the workspace so that brightness of the light source does not seem so bright.
If the angular displacement of light source increases, it reduces the glare problem in the building.
Guyton, Arthur C. & Hall, John E. (2006). Textbook of Medical Physiology. 11th edition. Elsevier Saunders, Philadelphia, UWS Hawkesbury, 612/1.
Gordon, Gary & Nuckolls, James L. (1995). Interior Lighting for Designers. 3rd edition. [John Wiley & Sons] New York: UWS Nirimba, 729, [28/5]
McGuinness, William J. & Stein, Benjamin (1955). Mechanical and Electrical Equipment for Buildings. 5th edition, [John Wiley & Sons], New York.
McMullan, Randall (2002). Environmental Science in Building. 4th ed. Macmillan, Basingstoke, Hampshire.
Rea, M.S. (2000). IESNA Lighting Handbook: Reference and Application. 9th ed. New York: Illuminating Engineering Society of North America.