What is a lighting fixture?
Lighting fixture, also known as “Luminarie” or "Light fixture", is a devise that projects, defuses and alerts the lights of the given lights source. Therefore, the main purpose of a lighting fixture is to direct light to the appropriate locations: be it a necessity or an element of décor. So, what does it actually take to choose a suitable lighting fixture for your project?
Choosing the right architectural lighting fixture
There are so many different factors which architects and lighting designers should take into account while choosing a suitable lighting fixture for the design. Lighting fixtures can be classified by various manners such as light distribution, application, the light source as well as the mounting method. Additionally, certain specifications such as color temperature, dimming, photometrics and CRI are also essential factors to consider. In this post we will discuss all of these lighting fixture classifications and specifications one by one.
The light source
Light source is the part of the luminarie which produces light. Examples of the light sourse include LED, incandescent lamps, fluorescent lamps and HID lamps. However, LED is the most modern solution which currently exists on the market and thus worth our attention. LED stands for light emitting diode. Its functionality is based on electricity that passes through its electronic components and as a result, light is produced. Some of the advantages of LED lights include longer life span, energy efficiency, cost-efficiency in the long run, little amount of heat produced as well as environmental benefits.
One of the main purposes of lighting fixtures is to direct light where it is needed to be directed. The chart below shows different types of luminaries based on the destination of the light.
UFF stands for upward flux ratio and determines how much light is directed upward. In turn, DFF stands for downward flux ratio and represents the percentage amount of lights distributed downwards.
UFF – 0-10%, DFF-100-90%
In these types of lighting fixtures, almost all the light is directed downwards. Good examples of direct lighting are troffer and downlights. These types of lights are recommended to be used in applications where light plays an essential role (e.g. hospital, office, kitchen).
UFF – 10-40%, DFF – 90-60%
The distribution of light in semi-direct light is primarily downward. However, a small upward component enables to make shadows softer. Semi-direct light can be used in places where strong light is not needed (e.g. storage, hallways, shopping malls).
UFF – 40 – 60%, DFF – 40-60%
In general diffusing light, the downward and upward components of lights are roughly equal and spread the light around the area. In turn, this enables a soft dispersed light and almost no contrast between light and shadow.
UFF – 60-90%, DFF – 40-10%
The distribution of light is mostly directed upward with a small downward component. This lighting solution is most often used for indoor decoration purposes, not as the main source of light.
UFF – 90-100%, DFF-10-0%
The light is fully directed upward and bounces off the walls, ceiling or floor. By using indirect light, it is very difficult to have a fully illuminated area.
Luminaries can be also categorized by the used application. In a broader sense, light fixtures can be divided into two major categories: outdoor and indoor. Indoor application can include pretty much any application inside - office, retail, school, hospitality and industrial among many others. Outdoor luminaries can include parking lots, landscape lighting, facade pathways and stairs. While some of the outdoor luminaries can be used inside, the reverse is not possible, as indoor luminaries are not sealed against moisture and adverse climatic conditions can destroy the light.
Lighting fixtures differ by their mounting method. Architectural lighting fixtures can include surface-mounted, recessed-mounted, wall-mounted, pendant-mounted as well as track-mounted. Obviously there are many other categories as well as subcategories, but those are the most commonly used lighting fixtures in architectural design.
Recessed-mounted fixture is a lighting fixture that is mounted in a hollow opening in a ceiling in a way that the lighting fixture itself is inside of the ceiling, while a glass panel distributes the light in the space. Troffer is a good example of a reassessed light.
Surface-mounted fixture. A surface mounted lighting fixture is simply attached to the surface. Unlike in a recessed mount, in surface mount the lighting fixture is not mounted in a hollow opening, but simply attached to the ceiling or wall.
The following types of lighting fixture follow the same type of mount as they are attached to the surface and therefore can be defined as surface mounted lights:
Ceiling-mounted fixture is a lighting fixture which is attached to the ceiling. This type of light is suitable for ambient lighting of the space.
Pendant-mounted fixture. A light fixture attached to the ceiling and hangs down from the ceiling on a rod or cord. Pendant lighting is not only a great decorative addition to the interior, but also an excellent lighting source.
Wall-mounted fixture is a lighting fixture which is installed to the wall. This type of light is most commonly used for exterior illumination.
Track-mounted light is the type of light where a lighting fixture is attached to a track. This type of light is mainly used for accent lighting.
Color temperature of the lighting source
Color temperature describes the light appearance perceived by people. It is measured in Kelvins (K) and the scale ranges from 1000 to 1000 K. The higher the Kelvin, the whiter the color temperature is. The main types of color temperatures are: warm-white (2700K – 3000K), Bright White/Cool White (3500K – 4100K), and Daylight (5000K – 6500K). The first one creates a cozy and welcoming atmosphere, the second one is mostly used for commercial applications, while the third is suitable for industrial use. If you want to know more about color temperature, view one of our earlier articles.
Dimmers are devices that enable the premise users to control the brightness of a light fixture. Today, there is a great amount of different dimmers which vary from basic wall-mounted dimmers to more advanced software systems.
Photometrics or sometimes informally called light output is a term which describes the quantity and distribution of the light produced by a lighting fixture. In other words, it describes the amount of light needed to illuminate a certain space. Photometrics is measured in lumens.
CRI or the Color Rendering Index measures the rendering of colors of objects in the space, compared to daylight. In other words, CRI measures the light source’s ability to show the colors of objects realistically. CRI is measured on a scale from 0 to 100; the higher the CRI, the more “accurate” the color rendering is. Light sources which have CRI between 80 and 90 are considered to be most acceptable for the majority of applications, while CRI greater than 90 should be used in applications where accurate color rendering is required.
We hope that this article will help you to make your first step in selecting suitable lighting fixtures for your project. Also, to make browsing, selecting and installing the lighting fixtures in Revit easier, Winled’s IT-department together with BIM-specialists created LIGHTS add-in for Revit. LIGHTS is a full LED luminaire library from Winled featuring always up-to-date luminaires.