Mga Paktor nga Isipon sa Disenyo sa Interior Lighting

Pangkalahatan nga Interior Lighting sa Hinahon ug Kasagaran

Nabati nato ang elektrisidad sa mga panahong hinahon kung ang mga silid-eskwela, opisina, ug uban pang mga lugar sa trabaho ginlihok pinaagi sa prismatic o translucent globes. Ang mga butang ini gisulob sa techo ug naglubos incandescent lamps sa pipila ka paagi aron mobuti ang lumens sa direkta ug indirect sa plano sa trabaho. Ang pagkamodulo sa mga butang ini mahimong mao ang reflections gikan sa mga surface sa silid. Ang mga glass enclosing globes gamiton usab aron mas taas ang luminance. Busa ang lighting scheme niini nagbuhat og considerable glare sa mga mata sa mga worker.

• Sa 1930s, ang totally indirect incandescent lighting napakita kasama ang Pan shaped o concentric ring luminaires. Ang usa ka half silvered lamp gisulob sa base up sa butang sa center sa unit. Sa sistema niini, gitransfer ang lumens sa lamp sa techo. Busa, ang techo naging ang light source. Tuyom nga ang indirect units niini nagbuhat og high quality, glare-free lighting. Apan ang lighting scheme niini labi ka inefficient. Wala ang lumens moadto sa direkta sa plano sa trabaho. Mga daghan lamps ang gikinahanglan sa isang espasyo aron mobuti ang work plane Illuminance. Busa, dako ang heat (infrared) ang giprodukto nga nagresulta sa thermal discomfort.

• Sa huling bahin sa 1930s, ang pagpakita sa fluorescent lamps ang nagsugyot sa pagbag-o sa interior lighting. Ang mga lamps niini adunay mas kaayo nga luminance kaysa sa incandescent lamps. Busa, wala na kini importante ang pagpadirekta sa tanang lumens sa techo aron mobalik sa direksyon sa baba. Pinaagi sa maayong arrangement sa louvers ug lenses, ang daghang lumens mahimo mopadirekta sa baba. Ang fluorescent lamp adunay lima ka beses kaayo nga efficacy kaysa sa incandescent lamp. Busa, ang 70 foot-candela sa fluorescent lighting mahimo mobuti nga mas efficient kaysa sa 30 foot-candela sa incandescent lighting.

• Ang pagpakita sa metal halide ug high pressure sodium lamps nagresulta sa daghang pagbag-o sa interior lighting sa 1960s. Niini giaddress ang energy crisis sa huling bahin sa 1970s. Ang mga lamps niini adunay kaayo nga concentration ug high luminance sama sa incandescent. Adunay sila ng efficacy pitu ka beses kaayo o mas dako. Busa, ang totally indirect lighting sa interior spaces naging ekonomikal nga feasible usa ra design sa paggamit sa mga lamps niini. Busa, ang pagbawas sa consumption sa energy mahimo mobantuha. Sa indirect lighting niini, ang mga levels sa Illuminance gilower. Ang sistema niini, bisan mobuti og reasonably uniform nga Illuminance sa entire work plan area, daghan pa gyud ang gikinahanglan sa additional Illuminance sa mga task locations.

• Busa, ang incandescent lighting dili recommended para sa general lighting sa interior spaces diin ang Fluorescent lighting padayon namdominate sa incandescent lighting scheme. Sa interior lighting, partikular ang 4 foot-candela, 40 W rapid start lamp ang pinaka commonly used fluorescent lamp. Metal halide lamps padayon nagpakita tuig-tuig sa indirect lighting, both luminaires suspended from the ceiling and in units built into office furniture. Ang pinaka popular lamp para sa mga uses niini mao ang 400 W phosphor coated metal halide lamp. High pressure sodium lamps sa carefully designed luminaires nagdumala og some acceptance sa interior lighting apan generally recommended lang sa rooms with high ceiling and where good color rendition is not important, such as gymnasiums.

Lamps for Interior Lighting

Ang interior lighting designer pinaagi sa pagpili sa mga lamps gikan sa among the following lamp types:

• Incandescent lamp

• Fluorescent lamp

• Metal halide lamp

• High pressure sodium

Ang bawgaw type adunay iyang kaugalingon nga set of strength ug weakness. Ang mga factors nga designer should consider sa pagpili sa lamp mao ang:

1. Consideration of luminous efficacy. Luminous efficacy mao ang ratio sa lumen output gikan sa lamp sa electrical power (in watt) input sa lamp. Ang required Illuminance kinahanglan mobuti sa lamp sa pagkombinado sa lighting economically.

2. Consideration of the life of the lamp kinahanglan gibuhat sa designers. Sila usab mogamit kung unsa ang mga difficulties sa pagreplace sa burned out lamps ug kung mas maayo ang group replacement sa lamps sa economic aspect o wala.

3. Ang lumen maintenance sa lamp mao ang importante nga factor. Makapanguha ang question kung importante ba ang certain minimum level of Illuminance sa tanang oras.

4. Ang sunod nga importante nga consideration mao ang color, ang factor sa appearance. Bisag parehas ang tanang lamps listed produce “white” light, lain-lain ang ilang CCT ug CRIs. Kinahanglan buhaton sa designers ang importance sa colors sa seeing task ug its surroundings nga faithfully reproduce.

5. Auxiliary equipments required along with the lamps make a big question. As we have seen, all gas discharge light sources require ballast, where as incandescent lamps do not. The types of ballast used can affect lamp output, life, starting reliability, system efficiency and occupant comfort.

6. Designers should think about what may be the other miscellaneous, i.e. whether any other factors are present in the particular environment or not, temperature is a problem or not and whether the area must be free from stroboscopic effects or not, electromagnetic interference disturb the activities going on in the space, the fumes are present which could produce corrosion or an explosive atmosphere etc.

Luminous Efficacy Consideration

The comparison of the first three factors for the four common lamp types is shown in the above table. Let discuss the lamp efficacy first. For incandescent lamps the efficacy ranges from 12 lm/W for the 40 W standard lamp to 22 lm/W for the 500 W standard lamp. For the incandescent lamps with the design kept unchanged, the lamp efficacy increases with the lamp wattage. It happens largely because the thicker filaments of the higher wattage lamps may be operated at higher temperatures for the same life. PAR (Parabolic Aluminized Reflector) and R (Reflector) lamps have generally lower efficacy than the standard lamps of same wattage. This is because PAR and R lamps are designated to have longer lives.
The fluorescent lamps provide much higher efficacies than the incandescent lamps inspite of having ballast losses. As an example, the 40 W standard cool white fluorescent lamp emits 3150 lumen initially and its ballast consumes 12 W. Thus the efficacy are 3150/40 = 79 lumens /watt initially and including ballast lost total wattage is 52 W and hence 3150/52 = 61 lumens / watt overall. This overall efficacy rating is being used for the latter figure in the market. In the lighting design scheme the Fluorescent lamps are used to be operated in pairs with single ballast to improve overall efficacy. For example, each of the two fluorescent lamps consumes 40 W and their common ballast consume 12 W, giving an initial efficacy of 68 lumen/W overall. In case Preheat fluorescent lamps the lamp efficacies are very low. In this modern age, fluorescent lamp ballast are so designed that they are considered as energy saving lamps with the highest luminous efficacy.
Metal halide lamps have higher efficacies than the mercury lamps. It is because of the addition of halide salts into the metal halide lamps. As an example 400W metal halide lamp emits 34000 lumen initially and its ballast consumes 460 W. It is giving an initial overall efficacy of 745 lumen/W. So the lower wattage sizes give the lower efficacies.
Again in case of high pressure sodium lamp, they provide the high efficacy. But the low pressure sodium lamp having higher efficacy is not suitable for interior lighting. It is because of poor color rendering properties. As an example, the 400 W sodium lamp emits 50000 initial lumens and its ballast consumes 75 W. So whole set up consumes 475 W. Its initial luminous efficacy is 105 lumen/W. By composition, the 100 W sodium lamp emits 9500 lumens, consumes 135 W, and has an initial efficacy of 70 lumen/W.

Life of the Lamps Consideration

The second column of the above table shows the life of the lamps in hours. We always assume that the operations of the lamps are at their rated voltage and normal temperature. The lives of the lamp depend on the lamp types. The life rating of the standard incandescent lamps is of 750 or 1000 hours. Again PAR and R lamps are rated at 2000 hours. For the fluorescent lamp, their life ranges are based on 3 burning hours start where as Preheat fluorescent lamps have life ratings at the low end of the range, namely 7500 or 9000 hours. Instant start lamp is durable for 12000 hours. Again the life of rapid start lamp lasts for 18000 or 20000 hours.
The metal halides lamps life is dependent on the number of burning hours per start. Their life ratings are for 10 hours per start. As an example the 400 W metal halide lamp has the longest life i.e. 20000 hours. The 1500 W lamp has shortest life i.e. 3000 h. Again all high pressure sodium lamps have a life of 24000 hours when they are used with the specially designed ballasts. High pressure sodium lamps are used in place of mercury lamps due to less wattage and higher life span. Mercury Lamps has 12000 hours life span.

Percentage Lumen Depreciation Consideration

The percent lumen depreciation of the lamps is shown in the table.
In case of Standard incandescent lamps, it depreciates in lumen output by 10 to 22% during lamp life.
In case of the fluorescent lamps, the 100 hours lumen value is called initial lumens and the lumen depreciation is calculated from that point onward and is based on 3 hour per start.
The mean lumen factor is the percentage of the initial lumens to be expected at 40% of rated life. Lamp lumen depreciation factor is the percent of the initial lumens to be expected at 70% of rated life.
For example, the 40 W standard cool white fluorescent lamp gives 3150 initial lumens at 100 hours and 2650 lm at 70% of rated life (14000 hours). Thus its lumen depreciation factor is 0.84 or 16% depreciation in lumen output.
High intensity discharge lamps have their initial lumen ratings at 100 hours. Lumen depreciation for these lamps is given in terms of mean lumens, which is the lumen output to be expected at about 70% of rated life. Metal halide lamps show greater lumen depreciation than do high pressure sodium lamps.

Color of the Lamp Lumens Consideration

Color of the lamp lumen is the fourth factor which is always considered by the designer. To measure the color, CCT (Correlated Color Temperature) and CRI (Color Rendering Index) are calculated to provide a suitable color appearance in the lighting design scheme.
CCT or Correlated Color Temperature means the temperature of the black body at which this black body radiation color is equivalent to the color of the lamp lumens.
CRI or Color Rendering Index means degree of closeness of the color of lumens from the lamps to the standard Lumen color. Standard lamps are, as per CIE recommendation, A, B, C, D55, D65 and D75. The type A is the tungsten filament lamp at 2856 K and the type B and C are tungsten filament lamp with some filter. D55, D