In general, we tend to take light for granted. However, a great deal of work goes into the installation of a lighting system, and illuminating a given space in the best possible way is not an easy task!
The principles of lighting technology guide us in the selection of appropriate lighting systems and a suitable setting that will illuminate a given space to perfection. These principles represent the set of techniques used to install light systems that produce optimal visual acuity and create a pleasant atmosphere.
Here then, is a summary of the principles of lighting technology.
For lighting to be effective in a given space, a number of variables must be taken into account, namely: human requirements, spatial architecture as well as the existing economy and specific surroundings.
Moreover, proper lighting must necessarily comply with a number of codes and standards. In Canada, we must adhere to that of the Illuminating Engineering Society (IES) standards as well as the Canadian Occupational Health and Safety Regulations.
A preliminary analysis is indispensable prior to choosing the most suitable lighting system; to that end, the following questions might be helpful:
- What are the underlying needs that this lighting system installation will address?
- Who will benefit from the installation of this lighting system?
- What activities or tasks will be carried out in this space?
- How does the environment affect the space that needs to be fitted with a lighting system?
- What are the maintenance requirements of the lighting installation?
Measures related to lighting technology
A number of additional factors and criteria come into play when selecting the most suitable lighting system and illuminating a given space in the most optimal fashion. Following is a list of some of these factors and criteria:
Brightness and illumination
The above two characteristics refer to the link between the fluctuation of light, the function of the space through which light travels and the thickness it penetrates. Both brightness and illumination are calculated using the Beer-Lambert Law, a mathematical formula that recognizes changes in light intensity based on distance light has travelled in a transparent environment.
Luminance of the sky
Luminance of the sky is merely the light that naturally shines on us at a given moment. We gather that this luminance is continuous whatever its course.
The luminous factor
We also need to take the luminous factor into account. It reflects the connection between light intensity level dispersed in one direction and the apparent surface of the light source in the same given direction. This factor is expressed in candela per square metre (cd/m2).
Glare prevents us from seeing clearly. It might be caused by a blazing, inconsistent or even by a poorly projected light source.
The amount of glare that originates directly from a luminaire can be calculated using the UGR method (Unified Glare Rating); it gauges the degree of discomfort caused by glare based on background luminance. The rating may vary from 10 to 30; the latter number determines the highest glare level.
The utilization factor
In the field of lighting, the utilization factor corresponds to the ratio of luminous flux consumed versus the total amount of luminous flux originating from a given light source.
Growing environmental and economic concerns compel us to prioritize the energy efficiency of our lighting systems and make a concerted effort to reduce energy consumption with the installation of a cost-efficient, well-adjusted lighting system.
Artificial light sources
As we all know, light originates from natural as well as artificial sources.
First, let us look at a number of artificial light sources:
- Incandescent lamps
- Fluorescent lamps
- MH systems (metal halide, sodium, and mercury)
- Induction systems, LED and plasma, etc.
- Ballasts as well as type circuits
Faced with this assortment of lighting types, it might be difficult, at times, to select the one best suited for our needs. Fortunately, there are several variables at hand to help make the best choice.
We need to select the proper bulb format. Should it be the standard form bulb, the spherical-shaped, flame or spot bulb? The articles entitled Bulbs in all their Shapes as well as Lamp Bases in All Shapes and Sizes offer useful information.
Additionally, there are lamp features to consider; information in this regard is usually found on the packaging. You might also wish to examine the guidelines in our article entitled How to Read Lighting Product Labels.
Colour temperature specifies the colour of a light source; it is measured in Kelvin and fluctuates from warm colours for a cozy atmosphere to cold colours that suit a contemporary style.
On this topic, read the article Colour Temperature.
Colour Rendering Index
The Colour Rendering Index allows us to determine the ability of a light source to accurately generate the colours of a given object. It is usually represented as a number that varies between 0 and 100, 100 being the natural source that renders all colours most accurately.
Read our article What is the Colour Rendering Index.
Efficiency is identified in Lumens per watt (lm/W) and corresponds to the ratio of luminous flux of a light source to the light power it consumes. The need for energy efficiency varies according to the activities carried out in the space. For more information, read our article How to Measure Light.
Light depreciation curve of the flux and lifespan of a lighting system
The light depreciation curve of the flux indicates the useful lifespan of a lighting system while the mortality curve indicates its total lifespan.
Thus, while a lighting system might still diffuse light, it may not be sufficient, in the long run, to correspond to existing needs. This is what is called the light depreciation. For more information, read our article Luminaire Dirt Depreciation
The mortality curve is the point in time when the luminous flux no longer operates.
Controlling light source
It is also important to examine the means to control a light source in terms of illumination time, dimming capacity as well as the compatibility of a given light source with various communication protocols (DALI, DMX, etc.).
Natural light sources
Above all, we need to understand that any natural light that comes to us pours down from the sky, be it a clear blue sky, a cloudy day, a clear day without sun or a clear day filled with sun. The amount of available natural light will vary not only according to the time of day and existing weather conditions, but also according to obstacles that are present in the space.
From this perspective, we need to acknowledge the factor known as light of day. This factor identifies the ratio between an exterior light source and available light inside a given space.
Moreover, natural light brings together two forms of light. The first is light that irradiates from the sun and the second is light diffused from the sky.
- Direct sunllight is simply luminosity that comes to us directly from the sun. Although this is an important light source, it is cannot be used at all times; it can also glare too brightly on the occupants. It needs to be considered accordingly.
- Sky diffuse light is the luminosity that comes to us quite naturally without any sun. It causes little to no glare; however, it might be insufficient, at times, to provide adequate lighting.
In the end, the amount of natural light that illuminates a given space may be affected by the environment and by the architecture of that given space.
Influence of the environment
The amount of light that a building receives depends on the environment that surrounds the building, such as the lay of the land, other facilities in the vicinity of the building, or even the landscape. For instance, a tree planted directly in front of a window will prevent light from shining through.
The influence of architecture
The intrinsic architecture of a building may also affect the amount of available natural light.
For example, the location of windows will redefine the natural light that shines into a room. Windows need to be installed in such a way as to maximize the input of sunlight. In this context, spaces that require morning light should be eastbound while other spaces that are occupied during the day should face south and rooms that are used in the evening should face in a westerly direction.
Read our blog sections entitled Lighting Application Recommendations to learn more about your application.
In conclusion, we have come to realize that the principles that underscore lighting technology are both numerous and somewhat complex. In the process of looking for and installing a lighting system that produces optimal visual acuity and creates a pleasant atmosphere, nothing can be left to chance.
It is essential to call upon our experts to ensure perfect lighting of your space and your buildings. STANDARD’s Project department is building energy audits to give an evaluation of the current lighting situation in their applications along with a solution to improve it.