Lighting System Monitoring - Literature review Example

Occupational and Environmental Hygiene Lighting System Monitoring 1. Executive summary Monitoring of the lighting system was done for over 7 hours running consecutively from 11am to 7pm on 22nd November 2012. During the monitoring period, the report has considered public library of Parramatta City Council as it was the designated area of operation chosen for the monitoring. The report has also considered this venue for purposes of estimation of average illuminance and effectiveness of task lighting. The lighting system monitoring or the survey had an objective of determining compliance of the lighting system which is in accordance with standards that have been proposed by the AS/NZS 1680 series. With such in mind, the determination of the compliance of the lighting system was done on a given space. The report will factor in the average illuminance which was measured through series of items. First, there was measurement of illuminance at of the series of points chosen and set out in a regular pattern. Secondly, there were calculations and determinations of mean of the values that had been measured through series of the items. In order to divide the task area or the chosen venue into equal number and thereafter determining minimum number of measurement points and position respectively, there was usage of room index equation. Giving the figures of the room which stood at (18×7=126 m2) and the Room Index Formula (RIF) which could as well represent the calculation method, the report considered 70 points so as to facilitate measurement of the average luminance. While measuring the illuminance levels within the library room, a model 407026 Light Meter was used. Also done in the room was the measurement of illuminance which was done through the aid of designated stray light and electric lighting system from the surrounding rooms within the library and through exit doors and windows. Important to mention is that the monitoring considered minimising space within the library room for effectiveness and such was done using curtains. The Standards Australia/New Zealand Online (2008) has set modern maintained illuminance standards specifically for public libraries. With this in mind, the report has considered comparison of such standards with the result the monitoring survey obtained. And as a result, the comparison shows that on average, the library room illuminance was considerably above the occupational level that has been recommended (320 lx) if reading, training and other educational activities need to take place in the library. In other words, such comparison grants that light monitoring survey carried out in the library provided the illuminance that can be considered suitable for carrying out visual related tasks with levels of difficulties differing significantly. Such difficulties ranged between moderately difficulty light related tasks to difficult light related tasks with what the report can term as small detail measured between 3-5 min arcs or with low contrast. Index Executive summary……………………………………………………………………………………………………………………1 Introduction……………………………………………………………………………………………………………………………….4 Methodology……………………………………………………………………………………………………………………………..6 Results……………………………………………………………………………………………………………………………………..10 Discussion………………………………………………………………………………………………………………………………..12 Conclusion and Recommendations………………………………………………………………………………………….13 References……………………………………………………………………………………………………………………………..14 Appendix…………………………………………………………………………………………………………………………………15 List of Table Table 1: Number of points for measuring illuminance……………………………………………………………..8 Table 2: Estimation of room index & illuminance measurement grid……………………………………..10 Table 3: Summary of Light Monitoring……………………………………………………………………………………11 2. Introduction Researchers have continued to show significance of lighting especially where physical related works are involved. American Conference of Governmental Industrial Hygienists (ACGIH) (2007) for instance highlights that proper lighting at working areas has positive impacts on the worker as such enables an environment where workers will be guaranteed of protection, safety and welfare in cases where such work is expected to run for a long time. On the other hand, Perkins (2008) writing on Modern Industrial Hygiene believes that when areas of work are well illuminated then we are guaranteed of a protected eye besides prevention of occupational accidents that have been witnessed in busy and poorly illuminated working areas. It therefore stands that when planning to install lighting systems in a working environment; public library for this case, lighting system should be designed in a manner that the intended users will be able to carry out their physical activities in an area that not only provides safety but visual environment for the intended purpose. Explaining workability, the report has adopted regarding the design of the interior walls of the library, the Standards Australia/New Zealand Online (2006) published has comprehensive standards that should be followed while lighting interior of rooms. The standard further explains that while lighting a given space with relation to the target users of that particular space then priority should be the provision of visual environment. However, American Conference of Governmental Industrial Hygienists, Perkins and Australia/New Zealand Online note that in as much as institutions endeavor to provide needed lighting facilities in the working area, such is dependent on other factors. Australia/New Zealand Online for instance argues that for efficient lighting over a given period of time within a working environment, there need to be distribution of light which should be there throughout the working space. American Conference of Governmental Industrial Hygienists and Perkins on the other hand concur that a factor that should be considered is the choice of the colour for the intended room. Such also goes hand in hand with the relevant reflecting surfaces. Anchoring the significance of the choice of colour while designing lighting system of the room, Cherrie et al. (2010) explain that poor choice of a colour for the room significantly affects light reflection and when a worker is exposed to such environment for long time then s/he is likely to have the eyes fatigued which ultimately leads to accidents and or inefficiencies. Cherrie et al. add that a room that fall short of the recommended lighting standards and recommendations has been a common problem contemporary workers face. It is however paramount to mention that among the factors that have been mentioned above, the Standards Australia/New Zealand Online (2006) has proposed two factors that supersede the above. Such are the Task Performance Potential and Task Performance Attitude which has been seen to dictate performance of individual’s performance. Still with Standards Australia/New Zealand Online (2006), the task visibility can easily determine elements that are seen to be difficult and can be detected and recognised while performing some tasks. It is also important to note that reports continue to suggest other factors that are able to affect a critical detail. Ignacio and Bullock (2006) mention luminance and color between the detail under observation and its background as an example of such factors; McPhee (2005), researching on Practical Ergonomics suggests contrast in luminance or adoption luminance as another factor. Among the factors mentioned above, luminance of the surrounding (for this case library) and luminance of the task still stand out to be undisputed factors (Standards Australia/New Zealand Online 2006). Cherrie et al. (2010) also suggest a factor in regard to what constitutes a critical detail. According to them, though provision of sufficient illuminance should be regarded as a key factor, task visibility also depends on how the available light has been applied. With all these factors under considerations, the report carried a comprehensive analysis and average calculations of illuminance as one of its considered factor which affects the task visibility in the library. When carrying out light monitoring in a place, it is fundamental to derive average measurement so as to enable determination of compliance of the lighting system in the designated areas (Standards Australia/New Zealand Online, 2006). Furthermore, calculating average illuminance has been used as a foundation for the purposes of ascertaining how to modify or replace existing lighting system or for maintenance of data. And for this case, the lighting monitoring at the public library aimed at coming up with the measurement of average illuminance so as to check whether there is compliance with minimum recommendations that have been proposed for the task. And with respect to that, considerable measurements were supposed to be done in the library so that average illuminance value that acts as a representative could be obtained. Having ability of estimating average illuminance and the effectiveness of the task lighting, this report has considered working with the public library. The library has standard measurement that is required by Standards Australia/New Zealand Online (2006). Being rectangular in shape, with its length 22 m and width 12 and height of its ceiling at 2.5 m, it can be realised that an individual working in the library has a working plane of over 0.85 m which is above the level of the floor. More to this, the library has a total of 35 fluorescent lamps situated at key points. The library room also has reading fixed chairs placed one meter way from each other with reading tables. Since workers or members of public taking studies in the library work with fixed tables, there is a localised general lighting system in the room that was installed specifically for such task areas so that there is adequate provision of the required task illuminance in the designated reading areas. With the help of lumen method that the library also adopted, individuals in the library working from fixed chairs do not strain. 3. Methodology 3.1. Illuminance measurements There has been a proposal regarding how effective light monitoring activities should measure average illuminance is a space. This include; determination of the calculation of mean of the values that had been obtained in terms of illuminance and secondly, measurement of illuminance at a given points within the library (Standards Australia/New Zealand Online, 2006). The data obtained by following Australia/New Zealand Online standard has been useful in two ways; a. Estimation of the relative location of the library points with respect to actual uniformity of the luminaries and illuminance available b. Estimation of the uniformity points which will be based on the accuracy estimated from number of points and the spacing of the measurement the library has On estimation of data based on the standard set, Ignacio and Bullock (2006) also add that even though the two above points have been crucial in illuminance measurement, light measurement accuracy within the interior areas of the library also depends on the number and arrangement of measurement points. 3.2. Determination of Illuminance measurement points Determination of illuminance measurement points has contributions from scholarly articles. For instance, Cherrie et al. (2010) believe that to achieve accurate assessment of the average illuminance, two things need to be done; ensuring sufficient number of measurement points as well as sufficient number of arrangement points. Other than the idea of Cherrie et al., ACGIH (2008) while writing on Control Banding believes that achieving accurate assessment of the average illuminance also depends on selected measurement areas which should cover the selected space intended to be measured at the same time ensuring that physical environment is represented. It is important to note that to come up with minimum number of measurement points and the respective position, there need to be a determination of index equation of the library room so that the task can be divided in equal number. Having the measurement of the library as 18×7=126 m2 and with Room Index Formula (the calculation method), the report realises that there was at least 50 points needed in order to measure the average illuminance. As suggested by Standards Australia/New Zealand Online (2006) that measurement area in the library needs to be at least square, based on the measurement of the library room, coming up with even number of squares was not possible thus making an increment to the points to 14x5 or 70 paramount. Table 1 below comprehensively shows how new figures have been adjusted. While determining illuminance measurement points, the report considered that sometimes there could be considerable errors increasing especially if the grid of the measurement points coincides with lighting fittings. To curb the irregularities or errors witnessed, the report monitoring programme considered increasing number of measurement points so that there is avoidance of disturbance that might arise. Lastly, within the library, there was a calculation of the distance between points along the length of the library and points across its width. Table 1: Number of points for measuring illuminance Room index Minimum number of measurement points For ± 5% accuracy For ± 10% accuracy RI < 1 8 4 1 < RI < 2 18 9 2 < RI < 3 32 16 RI > 3 50 25 3.3. Floor Plan Measuring of the illuminance levels at a public library of Parramatta City Council was necessitated through the use of a modern Light Meter of Model number 407026 and Version number 23. The model was preferred as it had other advantages over the previous versions. For instance, it can be able to offer data record and relative display mode as well as selectable lighting types. Using the 70 equal squares that had initially been divided, light meter was thus used to facilitate calculation of illuminance within the center of each area thereafter determining mean values. During monitoring, fluorescent tubes were selected as the preferred lighting type while LUX as the desired unit to be used in the library. Therefore using LUX for that purpose, it meant that it needed to be adjusted to 2000LUX range. Stray light and electric light system were used in the measurement of illuminance through the surrounding rooms and the external windows of the library. Curtains were also used to minimise space so as to enhance efficiency. It was realised that with the fluorescent tubes chosen, they could take time before their actual light is realised immediately they are switched on. To avoid the error in recording, the tubes were given over one hour so as to stabilize their output before actual measurement commences. Moreover, before using the light meter, all lumps that were to provide light in the library were cross-checked to ensure they are neither stained nor dirty. In accordance with the Standards Australia/New Zealand Online (2009) on Interior Lighting, buildings whose floors are larger than 100m2­ should be treated differently. It adds, “Such areas where the design is of a consistent or repetitive basis, measurements need not be conducted for the entire space” (p. 10). Bringing this interpretation to library floor, there was a need to prevent localised effects of individual luminaires; something that could be done by availing typically repeated patterns of luminaires as well as relatively close spacing of measurement points. On the other hand, Standards Australia/New Zealand Online, (2006) explains that if there is measurement of a single large area then the result will be enormous yielding quantities of repetitive data that is likely to ensure accuracy of result especially if the spacing between the measurement points chosen to minimise the amount of data is also very large. It therefore means that for accuracy, there need to be concentration of one or even smaller measurements points within the room rather than doing the same with large or the entire library. Basing the conclusion from the design public library of Parramatta City Council, task areas and non task areas are equally illuminated. And therefore it was prudent making calculations of the average illuminance on the task area. 4. Results The table below shows the summary of the light monitoring results Table 2: Estimation of room index and illuminance measurement grid 1 A B C D 2 Equation to be used in column C Value Unit 3 Date 22nd November 2012 4 Time of measurement 11-19 5 Room identification  Public library of Parramatta City Council  6 Type of activity Reading, writing, consultations, group discussion and borrowing of materials 7 Number of lamps 32 8 Length of room 18 m 9 Width of room 7 m 10 Floor area C8×C9 126 m² 11 Height of the luminaires above the plane of measurement 1.35 m 12 Room index C10/(C11×(C8+C9) 3.73 (Result was rounded to 4) 13 Number of illuminance measurement points taken 70 Table 3 Summary of Light Monitoring A B C D Equation to be used in column C Value Unit 14 Average room illuminance Eav = E1+E2 +E3 + .....+ En /N 640 lux 15 Measured/estimated circuit power 1280 W 16 Watta per square meter C15/C10 10.15 W/ m² 17 Installed Lighting Efficacy C14/C16 63.05 lm/W/ m² 18 Uniformity of illuminance 0.66 lux 19 Illuminance ratio between adjacent spaces Read More