1.0 Title of Experiment Experiment 1: Measurement of Illuminance 2.0 Objective of the Experiment Learning Outcome: To determine the luminous intensity of (2x36W) batten type light fittings. 3.0 Equipment 1. Luminous meter 2. (2x36W) batten type light fittings 3. Laser distance measure. Figure 4.1: Luminous meter & laser distance measure Reference Standard: IES Lighting Handbook (1968) Light 1 Ceiling Y Lux Meter Given the Illuminance Formula (or Cosine Law of Illuminance) is: E= 𝐼 × 𝑐𝑜𝑠𝜃 𝑑2 Where, E= Illuminance (or density of luminous flux) reaching a surface (lm/m² or lux) Light 2 I= Luminous intensity or strength of a light source (candle power or candela, cd) D= Distance between light source and surface (m) Find the luminous intensity of the lights. Conversion: 1 candela = 12.57 lumen 1cd/m² = 12.57 lm/m² (lux) 4.0 Precaution 1. Care must be taken to ensure that light incident on the sensor is not obstructed by the operator or any objects that are not part of the measurement such as shields for reflections. 2. Check the zero setting on the scale when the sensor is fully covered. 3. Check the condition of the battery in the instrument. 4. The artificial light source (fluorescent lamps) should be switched on for about 15 minutes before the measurements are taken in order to allow for the lamps to be completely warmed up. If the luminary (light fitting) is of the fully enclosed type, a longer stabilization time is needed. Note: E (artificial light) = E (Lights ON) – E (Lights OFF 5.0 Experiment Procedures 1. Luminous meter was placed in the middle path between 2 light fittings as shown in Figure 1. (b must be equal distance) 2. Distance a is measured vertically downwards to working plane where the lights measurement is taken. 3. d is calculated using Pythagoras Theorem. 4. The illuminance (lux) from the luminous meter is calculated. Substitute into the equation given and solve to determine the luminous intensity. 5. The experiments are repeated at various spots n different rooms in the building laboratory with the lights on and off.) 6.0 Experimental results Location a (m) b (m) d (m) Theta, Horizontal 2.967 on floor 1.805 3.47 31.31° Horizontal 2.36 on chair 1.805 2.97 37.41° Vertical on floor 2.967 1.092 3.16 20.21° Vertical on chair 2.36 1.092 2.60 24.83° 7.0 Discussions Horizontal on floor E (artificial light) = 52.3 (Lights ON) – 21 (Lights OFF) = 31.3 lx 𝐼 E = 𝑑2 ×𝑐𝑜𝑠𝜃 31.3 = 𝐼 3.472 ×cos 31.31 ° I = 441.12 cd Horizontal on chair E (artificial light) = 48.3 (Lights ON) – 15.3 (Lights OFF) = 33 lx 𝐼 E = 𝑑2 ×𝑐𝑜𝑠𝜃 33 = 𝐼 2.972 ×cos 37.41 ° I =366.47 cd Vertical on floor E (artificial light) = 45.1 (Lights ON) – 7.8 (Lights OFF) =37.3 lx 𝐼 E = 𝑑2 ×𝑐𝑜𝑠𝜃 37.3 = 𝐼 3.162 ×cos 20.21 ° I = 396.90 cd Vertical on chair E (artificial light) = 39.8 (Lights ON) – 7.9 (Lights OFF) = 31.9 lx 𝐼 E = 𝑑2 ×𝑐𝑜𝑠𝜃 31.9 = 𝐼 2.602 ×cos 24.83 ° I = 237.61 cd Hew Kian Lock (17WVD03975) Individual Introduction Good lighting plays an important role in safeguarding health at work by enabling employees to perform their work comfortably and efficiently. It also allows employees to read clearly labels and safety instructions (such as those affixed to chemical containers) to ensure compliance with safety measures for the prevention of hazards. Accordingly, there should be an appropriate level of the light falling on the surface on which employees are working. Excessive contrast, strong glare and light flickering in their fields of vision are also inappropriate. Measurement of illuminance is a common parameter in a lighting assessment. In order to perform this measurement, light is measured by using a lux meter which is used to measure the intensity of light falling on a surface. In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye. intensity is the candela (cd), an SI base unit. Individual Discussion 1. Explain the following terms: a) Light – Light is energy in form of electromagnetic radiation. b) Luminous intensity – Luminous intensity (I) is the power of a light source or illuminated surface to emit light in a particular direction. c) Luminous flux – Luminous flux (F) is the rate of flow of light energy. d) Illuminance – Illuminance (E) is the density of luminous flux reaching a surface. 3. Compare the results of illuminance, E (lux) obtained from your experiments in the various rooms with values obtained from standard lighting requirements. What are some typical values of service illuminance for (a) street lighting (b) hallway (c) home (d) classroom (e) office (f) shop display? Comment on your findings. a) b) c) d) e) f) Street Lighting – 100~200 lx Hallway – 100~200 lx Home – 150~300 lx Classroom – 300~500 lx Office – 300~750 lx Shop Display – 300~750 lx Generally, factors that affect the effectiveness of illumination are quantity and quality of light, amount of flicker, amount of glare, contrast and shadows. Each factor must be adjusted differently to optimize illumination in emergency, safety, operations, and security situations, for instance. Lighting Standards also serve to address the plethora of other concerns associated with the design, placement, installation, and minimum energy requirements and efficient allocation of illumination in different locations with different purposes, as well as the efficiency, durability, cost, and maintainability 4. Discuss some considerations affecting lighting design in buildings. Light quantity: Depends on the nature of the task & the light output of lamp & luminaire. Natural light : May be used as a complete source of light or to supplement artificial light sources. Colour quality: Depends on the requirements of the task & the colour rendering properties of the source. Glare: Depends upon the brightness & contrast of light sources & surfaces, & the viewing angles. Directional quality: Depends on the three-dimensional effect required & the nature of the lamp & luminaire. Energy use: Depends on the electrical efficiency of the lamps & the use of switches. Costs: Depend on the initial cost of the fitting; the cost of replacing the lamp ( including labour); & the electricity consumption of the lamps. Physical properties: Include size, appearance & durability of fittings. Individual Conclusion The number of lamp in a classroom, office or other place is very important for the person who stay there or doing the work at there. It is because if too many lamp in that place, the luminous intensity at there will high this will cause the person working at there felling unsatisfactory and inappropriate. If too less lamp also will cause the worker unsatisfactory and inappropriate. So the lighting standards are important to design the light in that place cant too high and cant too low must appropriate. In conclusion, this experiment has improve my knowledge about Illuminance. Thus, good lighting plays an important role in safeguarding health by enabling people to perform their work in good efficiency. References Labour Department, A Simple Guide to Health Risk Assessment - Office Environment Series - Lighting in Offices, Viewed 27 Nov 2017 Mcmullan, R., (2007). Environmental Science in Building. 6th Edition. New York: Palgrave Macmillan , Viewed 27 Nov 2017 Smith B.J,, Phillips G.M. and Sweeney M.,(1982). Environmental Science. New York: Longman, Viewed 27 Nov 2017 Wikipedia 2017, Luminous intensity, Viewed 27 Nov 2017 <https://en.wikipedia.org/wiki/Luminous_intensity> n.d., Illuminance - Recommended Light Level, Viewed 27 Nov 2017 <http://www.engineeringtoolbox.com/light-level-rooms-d_708.html>