We can find physical light within spaces direct or diffuse.

Diffused light reduces the presence of shadows and gives a feeling of relaxation and a more appropriate atmosphere for the inhabitant. This light ensures that no object is the protagonist of a space or has localized attention. All objects in a space with diffuse lighting have the same hierarchy or importance, on the other hand when we have direct lighting we create shadows and emphasis on the object or area that is being illuminated with it, since it is more punctual and creates an emphasis on the shapes and textures.

The objective that is always considered and as such the main one of the electrical and lighting installations within a space is to be able to offer its inhabitants the ability to perform tasks more quickly, comfortably and safely. It is then understood that this is in order to achieve objectives, which is why it is necessary to be able to offer sufficiently illuminated spaces to then have an adequate visual perception and thus carry out the work to be performed in the best way. This is why it is understood that if we change the tasks that must be carried out in a space, the physical lighting must change and vice versa. The following aspects must be considered for this.

• - Adequate color rendering indices where necessary.

• - Lighting design, when creating a project, the specific needs of the space as well as the areas and locations of the luminaires are considered.

• - Avoid glare, always think about visual comfort.

• - Calculation of luminous flux necessary for work areas that relate to the use of machinery.

• - Incorrect specification of luminaires can lead to vision problems, migraines, and headaches.

Situation - Luminous emittance.

• - Summer sun - 10,000 to 50,000 lux.

• - Daylight on a cloudy day - 5000 lux.

• - Work lighting - 1000 to 1500 lux.

• - Home lighting (living room) - 150 lux.

• - Street lighting - 1 to 20 lux.

• - Threshold of the eyes to distinguish color - 3 lux.

• - Full moon - 0.5 lux.

• - De manchas: distribuyen todo un conjunto de manchas luminosas por las superficies y perfiles del decorado, que se encuentra escasamente iluminado por una débil luz difusa.

• - De zonas: crea una serie escalonada de zonas de luz de mayor a menor luminosidad; de esta forma se centra la atención, se ayuda a expresar la distancia y se crea un ambiente.

• - De masas: imita el efecto natural de la luz.

Lighting in relaxation areas

A low level of general lighting combined with punctual light in spaces or light accents creates an atmosphere of relaxation; uniformity is one of the characteristics to consider for environments of this type. Low lighting levels are usually used, where the color temperature ranges between 2700 and 3000 K; This creates a warm and satisfying atmosphere, the luminaires are not placed directly or sometimes they are hidden and the light source is not perceived at first glance; An example of these applications are spas, massage areas or meditation centers.

Lighting in work centers

Visual fatigue") is caused if workplaces and traffic routes do not have sufficient lighting, whether natural or artificial, adequate and sufficient at night and when natural light is not sufficient.

The lighting installations in the premises, workplaces and traffic routes should be placed in such a way that the type of lighting provided does not pose a risk of accident to workers.[1]​.

Premises, workplaces and traffic routes where workers are particularly exposed to risks in the event of failure of artificial lighting must have safety lighting of sufficient intensity.[2]​.

Poor lighting causes visual fatigue" in the eyes, harms the nervous system, contributes to poor quality of work and is responsible for a good part of work accidents. A lighting system must meet the following requirements:

• - Lighting must be sufficient and necessary for each type of work. The optimal lighting for the human eye is that which achieves a luminance (lighting density) of 100 Cd/m² (candelas per square meter). A luminance difference greater than 10:1 produces glare.[3]​.

• - Lighting must be constant and uniformly distributed to avoid eye fatigue, which must adapt to the variable intensity of light. Violent contrasts of light and shadow, and oppositions of light and dark, should be avoided. The maximum recommended contrast for light is 3:1, this means that the lighting in the "central" areas does not exceed the lighting in the dark areas by more than three times (to avoid problems of adaptation to the light, which in a room would be 5 minutes of light adaptation time). (DIN 5035 regulations).

• - The light sources must be placed so that they do not dazzle or cause eye fatigue due to constant adaptations.[4]​.

Some measures that can be taken to meet these requirements are:.

• - Install light sources outside the direction of vision.

• - Use light diffusers, or barriers (for example matte glass, perpendicular metal sheets in office fluorescent tubes,...).

• - Placement of lights, fluorescent tubes parallel to the source of vision (they come towards us)...

• - Selection of lamps and bulbs with a low lighting density (luminance), for example fluorescent tubes or LEDs (5 watts can give 400 lumen) instead of traditional light bulbs (about 60 watts can give 800 lumen).

• - Use matte surfaces to avoid glare due to light reflection.

For precision work and visual acuity requirements, it is required that the distance to the workpiece be less than 600 mm, that the viewing angle be greater than 30 degrees, and that the illumination be greater than 500 lux.

For a desired light intensity (luminance), it is obtained with a number of watts per square meter (W/m²) of ceiling at a certain height (2 m / 3 m / 4 m):

• - (1000) - 50 / 60 / 64.

• - (750) - 38 / 45 / 48.

• - (500) - 25 / 30 / 32.

• - (300) - 15/17/19.

• - (200) - 10/11/13.

• - (100) - 5 / 6 / 6.

• - (50) - 3 / 3 / 4.

To this we must take into account that the efficiency of our vision changes with the light intensity (luminance); for example, at 75 lux it is 78%, at 100 lux it is 82%, at 250 lux it is 85%, at 500 lux it is 88%, at 1000 lux it is 90%, at 2000 lux it is 95%, and at 10,000 lux it would be the assumption of 100% efficiency. Furthermore, we must take into account the importance of contrast.

The UNE 12464.1 standard,[5]​ which is mandatory for member countries of the European Union, sets the levels required for indoor workplaces. Standard that must be followed at the origin of all lighting projects for indoor workplaces.

According to the World Labor Organization, lighting requirements in the workplace are divided into five different categories, depending on the level of detail required by the job.[6]​.

Depending on the color of the emission source, there is an effect on people's mood: white power supplies (daylighting) "activate" (produce a "daytime mood"), while traditional bulbs, with a high composition of red, produce passivity and an evening-night mood (sunset).

Another characteristic is that red and infrared are thermal emitters, with high heat transmission, and that they are the wave frequencies that plants mainly absorb during photosynthesis (hence they leave the residual frequencies, which they do not process into chemical energy: green).

Depending on the emission temperature, a color temperature is obtained, related to the heat sources. Traditional light bulb: 2800K (Kelvin); warm bulbs: 2900K; white light: 4000K; daylight (noon, clear sky): 5200 K; daylight (on cloudy days, which is bluer): more than 6000 K.

Depending on the color of the light, lamps are classified into three categories: warm light (high percentage of red, traditional bulb), neutral light (for work, offices, stores, etc.), and daylight (used in high lighting intensity needs).

A lighting standard is DIN 5035.

Minimum luminous emittance (emitted luminosity) for work centers according to different tasks.

Sight requirement - Luminous emittance (lux) - Example:.

• - (very low) - 50 - Traffic areas, warehouses, etc.

• - (low) - 100 - Rest areas.

• - (few) - 200/300 - Mechanical and workshop work, welding, planing, etc.

• - (average) - 500 - Offices.

• - (high) - 750/1000 - Technical drawing, precision mechanical work.

• - (very high) - 1500 - Manufacture of watches.

• - (Out of the ordinary) - 2000.

The luminous efficiency of incandescent lamps is 10 lm/W (lumens per watt). Incandescent halogen lamps have a luminous efficiency of 20 lm/W. The useful life of this type of lamps is 1000 to 2000 hours.

High-pressure mercury lamps achieve a performance of 40 to 55 lm/W and have a lifespan of 15,000 hours; They are used in public lighting or large spaces. Halogenated mercury lamps include a metal halide additive that adds more emission bands, bringing their luminous performance to 80 lm/W; They are used for interior or exterior lighting of facades, monuments, etc. Breaking it releases mercury vapor which increases the risk of mercury poisoning.

High pressure sodium lamps achieve an output of 100 to 120 lm/W, with a life of up to 16,000 hours. They are used in public lighting.

Fluorescent tubes have a performance of 60 to 80 lm/W, with a life of 10,000 hours. They are used in interior lighting.

Low-consumption bulbs, properly called compact fluorescent lamp (or CFL), have a somewhat lower performance than that of a classic fluorescent: 55 lm/W.

Light-emitting diodes (LEDs) have common performances of 55 lm/W in their best-known versions, but in recent years this aspect has been greatly improved (especially after the development of blue and white lighting LEDs) and they are marketed with performances of 90 lm/W (P7) and even 110 lm/W, thus achieving a new reason to make their way into the market; They are commonly used in interior lighting, study lamps, display cases, automotive signage, and in architectural uses.

The efficiency in the absorption of colors by the human eye is also relevant, since green will be absorbed more than ten times that of purple, since the efficiency of our color cones in absorbing these frequencies is very low.

There are various lighting control technologies: power regulation, proximity sensors, natural light-artificial light combination, double lighting and selective lighting.[7]​.

The interior lighting of a building or home is as important as the civil calculations of the work or the architectural design of the building. For example, the well-being and performance of employees in an industrial plant will largely depend on the quality of lighting.

The traditional F48T12 and F40T12 fluorescent tubes that are widely used (for example, in almost all drugstores), and the dichroic halogen bulbs raise hot and annoying air in the summer, and their maintenance is inconvenient and expensive.

On the other hand, compact energy-saving light bulbs, next to modern LED lamps; and fluorescent tubes or , produce a fresh, pleasant and relaxed atmosphere (although care for the proper functioning of the latter two is also considerable).

The results of this lighting are: a pleasant sensation in the environment with a clear and fresh light, greater productivity, fewer visits to the doctor, less cost of energy and electrical maintenance of the lamps (savings of 30 to 70%, depending on the technology used and hours of life of the luminaires); In addition, the subsequent environmental benefit must be added to all of the above.

Traditional incandescent bulbs are low cost, but with the disadvantage of their short life (1000 hours in normal conditions) and high energy consumption, which makes them unfriendly to the environment; in addition to its low color reproduction index in space. These, along with halogen lighting, are highly recommended with motion sensors.

Building managers work calmer and perform better when they are not absorbed by the multiple problems that traditional lighting brings with it: as in the case of fluorescent tubes with their expensive ballasts, accessories, transportation, high energy consumption, and maintenance of electrical technicians.

In addition to this and that, if these lamps were connected to motion sensors for lighting control, the useful life could be reduced so much that the normal expenses of maintaining the lights could be dwarfed by the abnormal excessive expense of fluorescent tubes. The constant turning on and off of lights in high-occupancy areas reduces the normal life of fluorescent lamps.

As has been seen, adequate and fresh interior and exterior lighting produces more comfort, and economic and personal well-being; For example: gratitude on the part of the residents of a building towards its administrator for a well-made investment: money that was previously invested in the expensive maintenance of lighting could be used for other expenses or particular or general needs, even luxuries.

DIALux software can be used as a powerful software to plan, calculate and visualize the lighting of indoor and outdoor spaces. With DIALux you can plan individual rooms, multi-storey buildings, paths, parking spaces and streets.

• - Luminance.

• - Luminous emittance.

• - Pavel Yablochkov.

• - Occupational health and safety.

• - Light pollution.

• - Interior lighting (good lighting in interior design).

• - Correct lighting.

We can find physical light within spaces direct or diffuse.

Diffused light reduces the presence of shadows and gives a feeling of relaxation and a more appropriate atmosphere for the inhabitant. This light ensures that no object is the protagonist of a space or has localized attention. All objects in a space with diffuse lighting have the same hierarchy or importance, on the other hand when we have direct lighting we create shadows and emphasis on the object or area that is being illuminated with it, since it is more punctual and creates an emphasis on the shapes and textures.

The objective that is always considered and as such the main one of the electrical and lighting installations within a space is to be able to offer its inhabitants the ability to perform tasks more quickly, comfortably and safely. It is then understood that this is in order to achieve objectives, which is why it is necessary to be able to offer sufficiently illuminated spaces to then have an adequate visual perception and thus carry out the work to be performed in the best way. This is why it is understood that if we change the tasks that must be carried out in a space, the physical lighting must change and vice versa. The following aspects must be considered for this.

• - Adequate color rendering indices where necessary.

• - Lighting design, when creating a project, the specific needs of the space as well as the areas and locations of the luminaires are considered.

• - Avoid glare, always think about visual comfort.

• - Calculation of luminous flux necessary for work areas that relate to the use of machinery.

• - Incorrect specification of luminaires can lead to vision problems, migraines, and headaches.

Situation - Luminous emittance.

• - Summer sun - 10,000 to 50,000 lux.

• - Daylight on a cloudy day - 5000 lux.

• - Work lighting - 1000 to 1500 lux.

• - Home lighting (living room) - 150 lux.

• - Street lighting - 1 to 20 lux.

• - Threshold of the eyes to distinguish color - 3 lux.

• - Full moon - 0.5 lux.

• - De manchas: distribuyen todo un conjunto de manchas luminosas por las superficies y perfiles del decorado, que se encuentra escasamente iluminado por una débil luz difusa.

• - De zonas: crea una serie escalonada de zonas de luz de mayor a menor luminosidad; de esta forma se centra la atención, se ayuda a expresar la distancia y se crea un ambiente.

• - De masas: imita el efecto natural de la luz.

Lighting in relaxation areas

A low level of general lighting combined with punctual light in spaces or light accents creates an atmosphere of relaxation; uniformity is one of the characteristics to consider for environments of this type. Low lighting levels are usually used, where the color temperature ranges between 2700 and 3000 K; This creates a warm and satisfying atmosphere, the luminaires are not placed directly or sometimes they are hidden and the light source is not perceived at first glance; An example of these applications are spas, massage areas or meditation centers.

Lighting in work centers

Visual fatigue") is caused if workplaces and traffic routes do not have sufficient lighting, whether natural or artificial, adequate and sufficient at night and when natural light is not sufficient.

The lighting installations in the premises, workplaces and traffic routes should be placed in such a way that the type of lighting provided does not pose a risk of accident to workers.[1]​.

Premises, workplaces and traffic routes where workers are particularly exposed to risks in the event of failure of artificial lighting must have safety lighting of sufficient intensity.[2]​.

Poor lighting causes visual fatigue" in the eyes, harms the nervous system, contributes to poor quality of work and is responsible for a good part of work accidents. A lighting system must meet the following requirements:

• - Lighting must be sufficient and necessary for each type of work. The optimal lighting for the human eye is that which achieves a luminance (lighting density) of 100 Cd/m² (candelas per square meter). A luminance difference greater than 10:1 produces glare.[3]​.

• - Lighting must be constant and uniformly distributed to avoid eye fatigue, which must adapt to the variable intensity of light. Violent contrasts of light and shadow, and oppositions of light and dark, should be avoided. The maximum recommended contrast for light is 3:1, this means that the lighting in the "central" areas does not exceed the lighting in the dark areas by more than three times (to avoid problems of adaptation to the light, which in a room would be 5 minutes of light adaptation time). (DIN 5035 regulations).

• - The light sources must be placed so that they do not dazzle or cause eye fatigue due to constant adaptations.[4]​.

Some measures that can be taken to meet these requirements are:.

• - Install light sources outside the direction of vision.

• - Use light diffusers, or barriers (for example matte glass, perpendicular metal sheets in office fluorescent tubes,...).

• - Placement of lights, fluorescent tubes parallel to the source of vision (they come towards us)...

• - Selection of lamps and bulbs with a low lighting density (luminance), for example fluorescent tubes or LEDs (5 watts can give 400 lumen) instead of traditional light bulbs (about 60 watts can give 800 lumen).

• - Use matte surfaces to avoid glare due to light reflection.

For precision work and visual acuity requirements, it is required that the distance to the workpiece be less than 600 mm, that the viewing angle be greater than 30 degrees, and that the illumination be greater than 500 lux.

For a desired light intensity (luminance), it is obtained with a number of watts per square meter (W/m²) of ceiling at a certain height (2 m / 3 m / 4 m):

• - (1000) - 50 / 60 / 64.

• - (750) - 38 / 45 / 48.

• - (500) - 25 / 30 / 32.

• - (300) - 15/17/19.

• - (200) - 10/11/13.

• - (100) - 5 / 6 / 6.

• - (50) - 3 / 3 / 4.

To this we must take into account that the efficiency of our vision changes with the light intensity (luminance); for example, at 75 lux it is 78%, at 100 lux it is 82%, at 250 lux it is 85%, at 500 lux it is 88%, at 1000 lux it is 90%, at 2000 lux it is 95%, and at 10,000 lux it would be the assumption of 100% efficiency. Furthermore, we must take into account the importance of contrast.

The UNE 12464.1 standard,[5]​ which is mandatory for member countries of the European Union, sets the levels required for indoor workplaces. Standard that must be followed at the origin of all lighting projects for indoor workplaces.

According to the World Labor Organization, lighting requirements in the workplace are divided into five different categories, depending on the level of detail required by the job.[6]​.

Depending on the color of the emission source, there is an effect on people's mood: white power supplies (daylighting) "activate" (produce a "daytime mood"), while traditional bulbs, with a high composition of red, produce passivity and an evening-night mood (sunset).

Another characteristic is that red and infrared are thermal emitters, with high heat transmission, and that they are the wave frequencies that plants mainly absorb during photosynthesis (hence they leave the residual frequencies, which they do not process into chemical energy: green).

Depending on the emission temperature, a color temperature is obtained, related to the heat sources. Traditional light bulb: 2800K (Kelvin); warm bulbs: 2900K; white light: 4000K; daylight (noon, clear sky): 5200 K; daylight (on cloudy days, which is bluer): more than 6000 K.

Depending on the color of the light, lamps are classified into three categories: warm light (high percentage of red, traditional bulb), neutral light (for work, offices, stores, etc.), and daylight (used in high lighting intensity needs).

A lighting standard is DIN 5035.

Minimum luminous emittance (emitted luminosity) for work centers according to different tasks.

Sight requirement - Luminous emittance (lux) - Example:.

• - (very low) - 50 - Traffic areas, warehouses, etc.

• - (low) - 100 - Rest areas.

• - (few) - 200/300 - Mechanical and workshop work, welding, planing, etc.

• - (average) - 500 - Offices.

• - (high) - 750/1000 - Technical drawing, precision mechanical work.

• - (very high) - 1500 - Manufacture of watches.

• - (Out of the ordinary) - 2000.

The luminous efficiency of incandescent lamps is 10 lm/W (lumens per watt). Incandescent halogen lamps have a luminous efficiency of 20 lm/W. The useful life of this type of lamps is 1000 to 2000 hours.

High-pressure mercury lamps achieve a performance of 40 to 55 lm/W and have a lifespan of 15,000 hours; They are used in public lighting or large spaces. Halogenated mercury lamps include a metal halide additive that adds more emission bands, bringing their luminous performance to 80 lm/W; They are used for interior or exterior lighting of facades, monuments, etc. Breaking it releases mercury vapor which increases the risk of mercury poisoning.

High pressure sodium lamps achieve an output of 100 to 120 lm/W, with a life of up to 16,000 hours. They are used in public lighting.

Fluorescent tubes have a performance of 60 to 80 lm/W, with a life of 10,000 hours. They are used in interior lighting.

Low-consumption bulbs, properly called compact fluorescent lamp (or CFL), have a somewhat lower performance than that of a classic fluorescent: 55 lm/W.

Light-emitting diodes (LEDs) have common performances of 55 lm/W in their best-known versions, but in recent years this aspect has been greatly improved (especially after the development of blue and white lighting LEDs) and they are marketed with performances of 90 lm/W (P7) and even 110 lm/W, thus achieving a new reason to make their way into the market; They are commonly used in interior lighting, study lamps, display cases, automotive signage, and in architectural uses.

The efficiency in the absorption of colors by the human eye is also relevant, since green will be absorbed more than ten times that of purple, since the efficiency of our color cones in absorbing these frequencies is very low.

There are various lighting control technologies: power regulation, proximity sensors, natural light-artificial light combination, double lighting and selective lighting.[7]​.

The interior lighting of a building or home is as important as the civil calculations of the work or the architectural design of the building. For example, the well-being and performance of employees in an industrial plant will largely depend on the quality of lighting.

The traditional F48T12 and F40T12 fluorescent tubes that are widely used (for example, in almost all drugstores), and the dichroic halogen bulbs raise hot and annoying air in the summer, and their maintenance is inconvenient and expensive.

On the other hand, compact energy-saving light bulbs, next to modern LED lamps; and fluorescent tubes or , produce a fresh, pleasant and relaxed atmosphere (although care for the proper functioning of the latter two is also considerable).

The results of this lighting are: a pleasant sensation in the environment with a clear and fresh light, greater productivity, fewer visits to the doctor, less cost of energy and electrical maintenance of the lamps (savings of 30 to 70%, depending on the technology used and hours of life of the luminaires); In addition, the subsequent environmental benefit must be added to all of the above.

Traditional incandescent bulbs are low cost, but with the disadvantage of their short life (1000 hours in normal conditions) and high energy consumption, which makes them unfriendly to the environment; in addition to its low color reproduction index in space. These, along with halogen lighting, are highly recommended with motion sensors.

Building managers work calmer and perform better when they are not absorbed by the multiple problems that traditional lighting brings with it: as in the case of fluorescent tubes with their expensive ballasts, accessories, transportation, high energy consumption, and maintenance of electrical technicians.

In addition to this and that, if these lamps were connected to motion sensors for lighting control, the useful life could be reduced so much that the normal expenses of maintaining the lights could be dwarfed by the abnormal excessive expense of fluorescent tubes. The constant turning on and off of lights in high-occupancy areas reduces the normal life of fluorescent lamps.

As has been seen, adequate and fresh interior and exterior lighting produces more comfort, and economic and personal well-being; For example: gratitude on the part of the residents of a building towards its administrator for a well-made investment: money that was previously invested in the expensive maintenance of lighting could be used for other expenses or particular or general needs, even luxuries.

DIALux software can be used as a powerful software to plan, calculate and visualize the lighting of indoor and outdoor spaces. With DIALux you can plan individual rooms, multi-storey buildings, paths, parking spaces and streets.

• - Luminance.

• - Luminous emittance.

• - Pavel Yablochkov.

• - Occupational health and safety.

• - Light pollution.

• - Interior lighting (good lighting in interior design).

• - Correct lighting.