Tips for choosing light intensity
Generally speaking, Luminous intensity is translated as the ability of a light source to illuminate a specific direction. It is one of the 7 photometric quantities that form the basis of all measurements in terms of lighting. However, these quantities are often the subject of confusion.
In this context, Some clarifications on the characteristics of the main photometric quantities which are frequently confused with luminous intensity are necessary. Before determining how to choose the right light intensity for a light fixture, discover the different lamp technologies and in particular, the specific features of the LED lamp.
Understanding light intensity
Luminous intensity is generally confused with other photometric quantities, notably luminous flux, illuminance and luminance. It is then necessary to distinguish between these notions.
What is luminous intensity?
Expressed in Candela (Cd), luminous intensity measures the quantity of light diffused by a light source in a specific direction. Derived from a Latin word, this unit of measurement mainly means " candle " In this context, a candela is the equivalent of luminous intensity or the amount of light diffused by a candle in a horizontal direction.
This quantity does not take into account the observation distance of the directive source, but the quantity of light emitted by it. This implies that whatever the distance separating the latter from its observer, the value of the luminous intensity of the lighting remains the same.
What is the difference between luminous intensity and luminous flux? ?
Luminous intensity expresses the quantity of light emitted by the light source in a specific direction. Expressed in Lumen (lm), the luminous flux, for its part, represents the quantity of light diffused by the luminaire in a global manner.
There " shine » or the brightness of a bulb increases as the luminous flux, or number of lumens, increases.
Clearly distinguish between light intensity and illumination
Expressed in Lux, illuminance represents the quantity of light received by the illuminated location. It quantifies the number of luminous fluxes per square meter, that is to say the amount of Lumens per square meter (1 Lux = 1 Lumen/m²).
Unlike luminous intensity, illuminance varies according to the distance between the light source and the illuminated area. When the light source approaches the illuminated area, the surface area of the latter decreases and the amount of light it receives increases, and when it moves away from it, the opposite phenomenon occurs. In this case, the illuminated surface increases and the amount of light it receives decreases.
Luminous intensity and luminance : not to be confused
Luminance is the only photometric quantity that humans can perceive. Expressed in candela/m², it quantifies the glare of the luminaire. Just like the luminous intensity, the observation distance has no impact on its value.
However, the apparent surface, that is to say the area perceptible by the observer, can vary depending on the position of the latter. The latter can see the entire apparent surface when he stands in front of the luminaire. If he stands next to the luminaire, this surface decreases and consequently the number of luminous fluxes as well.
Good to know : luminous intensity and luminous power are two very distinct concepts.
Luminous power and intensity are two different concepts that you should not confuse either. The luminous power is expressed in Watts and represents the energy consumption of the bulb. Furthermore, it is in the interest of investing in LED bulbs like the LED 95 Milky distributed by Hoopzï . With a luminous power of 8W, it diffuses a luminous flux of 930 Lumens. With an incandescent bulb, a luminous power of 75W is required to obtain such brightness and 65W with a halogen bulb.
The different lamp technologies
On the market, you can find a wide selection of lamps that develop different characteristics. You should know that there are several lamp technologies divided into 4 distinct categories.
Standard incandescent lamps
Invented in 1878, the standard incandescent light bulb was the first light bulb to use electrical energy to operate. Filled with inert gas, the glass body of the bulb encloses a tungsten filament.
Although it offers very good color rendering, it has major drawbacks due to its uneconomical nature.
This model has a very limited lifespan compared to other lamp technologies, i.e. 1 000 hours against 2 000 hours for a halogen lamp. The incandescent bulb can quickly heat up and become hot. Therefore, it cannot be replaced immediately if it is burned out. Wait until it has cooled down before handling it.
The luminous efficacy of an incandescent lamp depends on several factors, including its state of wear and the mains voltage. In addition, it decreases over time.
Good to know : apart from decorative models, incandescent lamps no longer exist on the market. In application of a European directive, their importation and manufacture have been prohibited since the beginning of 2013.
Halogen lamps (halogen incandescent lamps)
The halogen lamp also includes a tungsten filament, but unlike the classic incandescent model, the bulb does not contain only gas. It consists of inert gas and a halogenated component.
Thanks to this halogenated component, this type of lamp benefits from higher brightness and longer life than those of the classic incandescent lamp.
The main drawback of the halogen lamp is its energy consumption. In addition, some models have been withdrawn from the market because they consume a lot of energy. However, it is possible to find halogen lamps that develop better energy performance.
Good to know : Halogen tubes are not very recommended for domestic use. Generally, they are available in high power, i.e. greater than 100 W. However, such light power is not essential for domestic use.
Compact fluorescent lamps
This type of lamp is an alternative to the classic incandescent bulb. It stands out above all for its good lighting capacity and its low energy consumption.
This low-energy lamp is nothing more than an improved version of the fluorescent tube to adapt to domestic use. It generally has the shape of a fluorescent tube folded on itself.
The compact fluorescent lamp is available in different models and can take the form :
- From a classic light bulb,
- From a tube bulb,
- From a spiral bulb,
- From a globe bulb.
However, this type of lamp has certain flaws that you should not take lightly.
The fluorescent tube contains mercury vapor. In case the bulb breaks, you must take some precautions :
- Do not inhale mercury vapor,
- Ventilate the room immediately to dissipate the steam (minimum 10 minutes) ;
- Put on gloves before handling the broken parts to avoid cuts.
Various studies have shown that compact fluorescent lamps emit a large quantity of electromagnetic waves. However, these waves can be broadcast within a radius of 30 cm maximum. To limit any potential health risks, it is advisable to avoid any exposure to these waves. These bulbs are not suitable for bedside lamps and even less for reading lights.
LED lamps
Unlike other lamp technologies, The LED lamp is equipped with an electronic device whose main role is to transform electricity into light. It is capable of producing light, even at very low voltage, while guaranteeing very good performance.
The main advantage of this type of lamp lies in its particularly remarkable progression. Indeed, manufacturers do not stop innovating their product to provide LED lamps that meet the needs of consumers.
The special features of the LED lamp
LED lamp, a highly scalable luminaire
When we talk about light intensity, it is difficult not to mention the subject of LED lamps. Appeared In 1962, the electroluminescent diode (LED) lamp stood out above all for its low energy consumption. It was originally intended for indicator lights on electronic devices, then for road and urban signage, and finally included in the list of equipment for domestic use.
LED lamps come in several types depending on the power of the bulb (W), the color temperature (°K), the luminous flux (Lumens), the style... At Hoopzï, for example, you can find different models like the Copper mirror head LED bulb (4W and 2 000°K) or even the LED floating globe 200 lampshade bulb (8W and 2 200°K).
LED is an economical and ecological lighting solution that is gradually replacing "classic" halogen or incandescent bulbs. However, it should be remembered that this solution is only effective if you choose a model that is suited to your needs and the room to be lit. To find out if the bulb meets your needs, check the indicators on its packaging. These represent the characteristics of the product in question.
What are the characteristics of an LED lamp? ?
Light power
The power of the bulb reflects the energy consumption of the lamp. For conventional bulbs, it can also be used to assess their light intensity. However, this unit of measurement can be misleading in the context of the LED lamp which is particularly energy efficient.
In fact, the brightness of a 40 Watt incandescent bulb and that of a 3 to 5 Watt LED are approximately the same.
On the product packaging, manufacturers often indicate the equivalent of a conventional bulb to the LED lamp in terms of power. For the LED 95 Clear at the house of Hoopzï , for example, it has a power of 7W equivalent to 60W for an incandescent bulb.
The luminous flux
If it is difficult to evaluate the brightness of an LED bulb with its power, you can refer to another quantity, that is to say the luminous flux expressed in Lumens.
In this context, Please note that a 3 to 5 Watt LED bulb can emit the same luminous flux as an incandescent bulb of approximately 40 Watts, or between 300 and 500 Lumens.
The nerve
The base is the element that allows the bulb to connect to the socket. It exists in several models :
- The E27 base : it is a large screw-in model. The same type as the LED bulbs distributed by Hoopzï.
- The E14 base : it is a small screw-on model.
- The GU10 base : it has 2 studs that you can fix by making a quarter turn.
- The GU5.3 or MR16 base : it is fixed using its 2 points.
The supply voltage
On the packaging of the LED bulb, manufacturers indicate the power supply voltage that is suitable for it. Some models can be connected to 12V with direct current, others to 12V with alternating current. There are also LED bulbs that operate on 230V alternating current.
It is strongly recommended to respect the supply voltage indicated on the bulb packaging. Otherwise, the bulb may burn out as soon as it is switched on.
Color temperature
This characteristic is a determining element, because it defines the atmosphere generated by the light emitted by the bulb.
Expressed in Degrees Kelvin (°K), the color temperature varies between 2 000° K and 6 500°K. There are 4 shades of color which generate 4 different atmospheres:
- Very warm white : between 2 000° K and 2200° K ;
- The warm white enters : 2,200° K at 3 200°K ;
- Neutral white : between 3 200° K and 5 000° K (equivalent to the color of daylight);
- The intense white or cool white: more than 5 000° K (not recommended for residential lighting).
Good to know: this data is provided for information purposes only.
Particularly for the bulbs distributed by Hoopzï, they generally vary between 2 000° K and 3 000° K.
The wavelength
The wavelength expresses the color of the LED lamp (red, green, yellow, etc.). This implies that it does not apply to white lighting LED lamps.
Color rendering index (CRI)
This unit of measurement is used to determine the LED bulb's ability to reproduce the color of the surface and objects it illuminates. It refers to daylight and varies between 1 and 100. The ideal CRI is greater than or equal to 80.
This table summarizes some essential characteristics of the LED lamp so that you can get an idea of its main qualities.
Features | Values |
Luminous flux | 300 – 1 000 Lumens |
Color Rendering Index (CRI) | 80 – 100 (reference is 1 to 100) |
Color temperature | 2 700°K – 6,000° (the LED bulb can diffuse a warm or cold light, depending on the model) |
Luminous efficiency | 30 to 100 Lumens/Watt |
Energy class | A+ (the bulb has high energy performance) |
Lifetime | 15 000 – 50 000 hours |
How to choose the right light intensity for a light fixture ?
The choice of brightness for all the rooms in the house should not be made at random. In fact, each of them is assigned to a specific function and its brightness requirements depend on it.
It is then appropriate to follow the recommendations of professionals regarding the amount of lighting needed for a room. To facilitate the calculation, they took into account the value of the lamp's illumination, that is, the amount of light received by the illuminated area.
Of course, the data in this table remain indicative, nevertheless, they can be useful to you in choosing the quantity of light necessary in your interior.
Room to be illuminated | Amount of light required per room |
Between 100 and 300 Lux | |
Living | Between 200 and 300 Lux |
Between 100 and 300 Lux | |
Between 100 and 300 Lux | |
Between 200 and 500 Lux | |
Bathroom | Between 200 and 500 Lux |
Toilet | 100 Lux |
Laundry room, garage, cellar… | Between 100 and 300 Lux, or even more depending on the activity carried out in the room |
Corridors and entrance hall | 100 Lux maximum |
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Some rules about lighting
To ensure good lighting in a given area, mastery of these few rules remains essential.
To start, you need to determine the room to be lit. The light intensity and lighting power requirements of the bedroom are not the same as those of the living room, bathroom or kitchen. This allows you to define the area to be lit and to get a precise idea of the brightness requirements of the room in question. Indeed, the bedside table requires a lower light intensity than the kitchen worktop.
You must also consider the style of room design. The brightness of a dark-colored living room will not be the same as that of an all-white living room, even if the two rooms benefit from identical lighting.
The color of the light emitted by the light fixture has a significant effect on your mood. It allows you to create an ambiance that suits your desires and the needs of the room. Know that warm light is favorable to relaxation, because it evokes both tranquility and comfort. On the other hand, cold light is favorable to work areas, it makes you as dynamic as it is active.
The Hoopzi Team
