General information, optic specifications, index

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L952D953_SRC.QXD 11-03-2004 08:21 Pagina 12.14 Information – Lighting technique However, the luminous intensity graph in the cartesian intensity diagram gives a much better indication of the beam shape.The luminous intensity in the cartesian diagram is given in absolute candela values.Along the horizontal axis the -values of the C-plane are given, while the vertical axis shows the absolute intensity values in candela. Utilisation factor table Room Index k 0.60 0.80 1.00 1.25 1.50 2.00 2.50 3.00 4.00 5.00 0.80 0.50 0.30 0.43 0.51 0.57 0.63 0.67 0.73 0.77 0.79 0.82 0.84 0.80 0.50 0.10 0.41 0.48 0.53 0.58 0.61 0.65 0.68 0.69 0.71 0.72 0.70 0.50 0.30 0.42 0.50 0.56 0.62 0.66 0.71 0.75 0.77 0.79 0.81 0.70 0.50 0.20 0.41 0.49 0.54 0.59 0.63 0.68 0.71 0.72 0.75 0.76 0.70 0.50 0.10 0.40 0.47 0.53 0.57 0.60 0.65 0.67 0.69 0.70 0.71 0.70 0.30 0.10 0.36 0.43 0.49 0.54 0.57 0.62 0.65 0.67 0.69 0.70 0.50 0.30 0.10 0.36 0.43 0.48 0.53 0.56 0.61 0.64 0.66 0.68 0.69 0.50 0.10 0.10 0.33 0.40 0.46 0.51 0.54 0.60 0.63 0.65 0.67 0.68 The Utilisation Factor table enables the lighting designer to determine the number of luminaires required, or to calculate the illuminance realised with a certain lighting installation.Although a lot of calculation work has been taken over by computer, the Utilisation Factor table is still a handy tool for lighting designers.The Utilisation Factor (UF) of a lighting installation represents the percentage of the luminous flux of the lamp(s) that reaches the defined working plane in the room, which has to be seen as the efficiency of the lighting installation.The Utilisation Factor depends on: - light distribution of the luminaire - luminaire efficiency - reflection of ceiling, walls and floor/working plane of the room - room index k The room index k represents the geometrical ratio of the room, and can be expressed as: 0.30 0.30 0.10 0.35 0.42 0.48 0.53 0.56 0.60 0.63 0.65 0.67 0.67 0.30 0.10 0.10 0.33 0.40 0.45 0.50 0.54 0.59 0.62 0.64 0.66 0.67 0.00 0.00 0.00 0.32 0.39 0.44 0.49 0.53 0.58 0.60 0.62 0.64 0.65 k = L x W Hwp ( L + W) Where: L = length of the room (m) W = width of the room (m) Hwp = height or vertical distance between the luminaires and the working plane Lumen method: The UF can be looked up in the table for a range of values of the room index k and a number of reflection value combinations.After determining the UF for the specific layout for a luminaire, the number of luminaires for a specific illumination level can be calculated with the formula: E x A N = x UF x MF Alternatively, knowing the number of luminaires, the resulting illuminance can be calculated with the formula: x N x UF x MF EAV = Reflectances (%) for ceilings, walls and working plane Recessed mounted A 12.14 GENERAL INFORMATION, OPTIC SPECIFICATIONS, INDEX Where: N = required number of luminaires EAV = specified average illuminance in lux n = nominal lamp flux per luminaire (lumen) UF = utilisation factor MF = maintenance factor A = surface area of the room (m 2 ) Quantity estimation diagram Number of luminaires hroom: 2.8 m Reflectances: 0.70, 0.50, 0.20 60 Maintenance factor: 1.0 Recessed mounted 45 30 15 750 lx 500 lx 300 lx 0 20 60 100 140 2 180 (m ) The quantity estimation diagram gives a quick insight into the number of luminaires that will be needed to reach the desired illuminance in a room. The diagram gives the number of luminaires of one type needed for different lighting levels, as a function of the area to be illuminated.Three different diagrams exist.They are based on three fixtures' mounting heights (2.8, 6 or 9 m, depending on the typical application,) and are made for fixed reflection factors, as indicated in the diagram.The quantity estimation diagram should only be used when the luminaires are placed in a regular pattern, in, on or suspended from the ceiling. For calculation purposes the space to be illuminated is considered to be rectangular. The example shows that if 750 lux is required in an area of 100 m 2 ,32 luminaires have to be installed.The information from this diagram should be considered as a guideline. For exact figures, the lumen method or computer calculations are required.The maintenance factor used for this diagram is 1.0 but in practical situations a real maintenance factor has to be taken into consideration. Unified Glare Rating diagram (UGR) hroom: 2.8 m Reflectances: 0.70 0.500.20 Ceiling mounted : viewed endwise : viewed crosswise : Parallel to viewing direction The Unified Glare Rating is an indication of the direct glare perceived in a certain space illuminated by artificial lighting. According to CEN (European Committee for Standardisation) the Unified Glare Rating (UGR) should be determined according to the CIE tabular method.
L952D953_SRC.QXD 11-03-2004 08:21 Pagina 12.15 UGR is given in 5 classes (UGR= 16, 19, 22, 25 and 28; the lower the UGR, the less direct glare is perceived from the total of the luminaires in the installation).As the CIE tabular method does not give a quick insight into the UGR characteristics of a specific installation, Philips Lighting has developed the UGR diagram. For each installation with one type of luminaire, the UGR value to be expected in the application can be determined from this diagram. Note that the UGR values are given for two viewing directions to the luminaire, endwise and crosswise, and that the UGR might vary depending on the size of the space under consideration.The highest UGR value determines the quality of the installation. In the UGR diagram the UGR is represented for the specified height and reflection factors. Visual ambience diagram g h(m) 1 2 3 4 5 800 400 200 100 Eh (lx) 1 2 3 4 5 luminaire spacing (m) Downlights are often used for general lighting.Applying downlights, very attractive lighting with high contrast can be realised, but also diffuse uniform lighting.This very much depends on the light distribution of the specific downlight. The visual ambience diagram gives information on: - The spacing between the downlights required to obtain a certain average illuminance level at a specific mounting height. - The uniformity of the chosen lighting solution for different horizontal planes. Spacing: At the horizontal top axis, the average horizontal illuminance level is given (800, 400, 200, 100 and 50 lux). For each illuminance two curved lines are visible in the diagram: - the left curve is valid for a small room with 4 x 4 luminaires in a square arrangement. - the right curve is valid for a large room with 10 x 10 luminaires in a square arrangement. For narrow-beam luminaires the differences between the small-room luminaire arrangement and the large-room installation are minor, resulting in one curved line only. The distance between the luminaire and the reference plane, on which the average horizontal illuminance is calculated, is indicated on the left vertical axis. The luminaire spacing to obtain the selected horizontal illuminance at the specified distance from the ceiling can be found on the lower horizontal axis. Emin Emax 0.1 0.3 0.6 Uniformity: The resulting uniformity for the selected spacing can be read from the diagram for various horizontal planes.The uniformity is defined as Emin /Emax.Three straight sloping lines in the diagram indicate three uniformity values: 0.1, 0.3 and 0.6.The uniformity determines the lighting effect that will be obtained: -Emin /Emax > 0.6 (in the diagram below the 0.6 uniformity line).The arrangement of downlights creates diffused, uniform lighting, and so a ‘functional’ lighting ambience. - 0.1 < Emin /Emax < 0.6 (in the diagram in between the 0.6 and 0.1 uniformity lines).The arrangement of downlights creates a lighting ambience that varies from lively to very contrasting. -Emin /Emax < 0.1 (in the diagram above the 0.1 uniformity line). The arrangement of downlights results in a non-uniform horizontal illuminance.The effect of the individual luminaires is clearly visible on the horizontal surface. In practice, it is important to check uniformity not only on the working plane, but also at different heights, for example at eye level. If the resulting uniformity is not in accordance with to the requirements of the application, another type of luminaire should be selected. Isolux diagram h(m) 1 /2E0 o 2 x 22 Ehor (lx) 1 / 2Imax o 2 x 29 h (m) E0 (lx) d(m) 1 1 /2E0 /2Imax 1.0 1.0 674 0.81 1.11 500 1.5 299 1.21 1.66 2.0 200 2.0 168 1.62 2.22 2.5 108 2.02 2.77 3.0 100 3.0 75 2.42 3.33 3.5 55 2.83 3.88 4.0 50 4.0 42 3.23 4.43 5.0 4.5 33 3.64 4.99 3.0 2.0 1.0 0.0 1.0 2.0 3.0 (m) The isolux diagram shows the illuminated area for rotationally symmetrical light distributions by means of isolux curves. The horizontal illuminance is indicated in relation to the distance (vertical and horizontal) to the luminaire. The shape of the isolux curves is dependent on the beam spread of the luminaire. 1 / 2 E 0 and 1 / 2 Imax indicate this in the graph.Additionally, the connected table offers the user information on: - the resulting illuminance at the beam centre. (E 0) - the diameter of the area in which the illuminance is better or equal to 50% of the illuminance E 0. - the diameter of the area in which the luminous intensity is better or equal to 50% of Imax, the intensity in the beam centre. GENERAL INFORMATION, OPTIC SPECIFICATIONS, INDEX 12.15
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