Friday, February 13, 2009

INTERIOR LIGHTING, an Introduction

Lighting is an essential aspect in an interior environment. Without light, an interior enclosure, could not be visually defined and identified. Within light, an interior environment could be clearly defined by the appearance of color, ambience, its spatial size and depth. Light, in a particular intensity, will enable us to visually identify further specific detail characters of materials such as texture, pattern, transparency, glossiness and other visual related characters.

Interior lighting design involves both quantity and quality of lights. The essential functions of interior lighting are:

1. To provide visual comfort
2. To provide comfortable working environment

3. To provide particular illumination effect

Scientifically, visible light could be defined as electromagnetic wavelength (ג) within 4000 Angstrom (Ǻ) to 7000 Angstrom (Ǻ). Human eye is closely related with the appearance of light. Human eye sensitivity is depending on the wa
velength of light. Less than 4000 Ǻ, it could be defined as ultra violet light. More than 7000 Ǻ, it could be defined as infra red light. Both ultra violet and infra red lights are not visible by normal human eyes.

Placed around electromagnetic wavelength of 5500 Ǻ, are combination of green and yellow colors. These colors at this range of electromagnetic wavelength provide best level of brightness to normal human eyes. Color of lights could be differed and identified by human eyes because different ranges of its electromagnetic wavelengths. Lamps produce both visible and invisible lights. Color of light is depending on its (electromagnetic) wavelength.

Light Color spectrum is one of important aspect in interior lighting design, because it delivers particular color effects against objects. There are two types of light color spectrum: continuous and discontinuous spectrum type. Light with continuous spectrum type will radiating all colors in the range of visible light, this will enable human eye to identify object in its best color visual interpretation. Meanwhile, Light with discontinuous spectrum type not radiate all range of visible colors. Other important aspects are luminous efficiency and lamp wattage that are associated with particular functional requirements.

Lighting source for an interior environment could be diff
ered to two types of sources. Natural lighting is the first type of source and artificial lighting is the second one. Natural lighting is simply defined as lights which are coming from every kind of natural light source such as sun or daylight. Meanwhile, artificial lighting is simply defined as the opposite of natural lighting source. Commonly, artificial lighting could be simply differed into electrical type and non-electrical type. Natural lighting and artificial lighting provide different color effects to objects in an interior environment. Each of natural and artificial lighting has different color spectrums.

Basically, electrical lighting source could be differed into two types of lamp:

1. Incandescent lamp
2. Electrical gas discharge lamp

Incandescent lamp is a source of
electric light that works by incandescence, an electric current passes through a thin filament, heating it until it produces light (Wikipedia). Incandescent lamp radiates all electromagnetic wavelengths that differ in its each wavelength. This mean that this type of lamp produces continuous light spectrum. According to this type of light spectrum, it could be said that generally incandescent lamp has the best color effect against objects.

Visually, color effect produced by incandescent lamp look warm in its yellowish color. Comparing to the other type of lamp, incandescent lamp has p
oor luminous efficiency. The luminous efficiency is poor, because too much electrical energy that converted into heat.

The second type is electrical gas discharge lamp. Light that is produced by this type of lamp is coming from an electric current passes particular gas inside a kind of tube. The light is produced by the impact of electrons that radiate from electrode device against electrons of the particular gas.

Fluorescent lamp is common example of low pressure gas discharge lamp. Fluorescent lamp radiates non-continuous color spectrum. This mean that fluorescent lamp not radiate all visible color spectrum (only radiate violet, blue, green and yellow). This also mean object that washed by fluorescent lamp will only reflecting particular only and object could not be identified in its true colors.

Fluorescent lamp also produces the un-visible ultra violet light. Particular gas at the internal side of the lamp tube will then convert the ultra violet light into useful visible light. Luminous efficiency of fluorescent lamp is much better than incandescent lamp. Average life cycle of fluorescent lamp is generally much longer than the inca
ndescent lamp type. Currently, in the market we can various fluorescent product lamp types such as TL, SL and PL in many various shape and size.

Another example of electrical gas discharge
lamp is natrium lamp a type of low pressure electrical gas discharge with most efficient illumination level. This type of natrium lamp only radiates yellow color spectrum, this mean it has worse color effect because whatever the object colors, it will only be reflected as yellow objects. This type of lamp is used for street lamp.

The basic thing is, selection of lamp fixture shall comply with the type of activity in a room and particular type of visual task. In an office working space fluorescent lamp and fluorescent downlights are used because the light effect commonly soft and properly fit for average three meters offices ceiling height. In case of a lobby room with high ceiling, it could be adequate to use metal halide lamp or halogen downlight. These type of lamp fixture could provide high illumination level on the floor surface even placed at six meter ceiling height. Sometime, two different types of lamp fixtures are mixed together to achieve better light effects for example is the mixing of white light of metal halide lamp and yellowish light of halogen lamp.

Lighting control is another important issue. Light from particular light source could be controlled to minimize glare, provide particular lighting effects and create room ambience. Since currently there is a global concern on energy saving issue, it will be wise that lighting design and planning shall also consider that the energy must be explored and used in a smart and efficient way.