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UNI EN 12464-1
The UNI EN 12464-1 standard deals with the issue of how to provide adequate and appropriate lighting for people who carry out visual tasks in the performance of their work.
In particular, the standard specifies what the lighting requirements are for people - with normal visual capacity and working at indoor workstations - that correspond to the needs of visual comfort and visual performance. The standard considers all customary visual tasks, with a particular focus on those performed at workstations with display screen equipment.
An important aspect of the EN 12464-1 standard is to consider the combination of quantitative and qualitative aspects, while emphasising the importance of light for people's health and well-being. The standard also highlights a highly topical issue: people receive positive stimuli and perceive greater well-being when lighting conditions can be varied over time not only in terms of illuminance and luminance distribution, but also in terms of the colour temperature range.
Location and workstation
The standard takes up and adapts already recognised definitions:
- the workplace is intended to house workstations on the premises of the undertaking and/or establishment and any other place of work within the area of the undertaking and/or establishment to which the worker has access in the course of his work (Directive 89/654/EEC);
- the workstation is the combination and spatial arrangement of the work equipment, surrounded by the work environment under the conditions imposed by the work tasks (EN ISO 6385:2004).
A number of parameters contribute to the characterisation of the lighting environment such as:
- luminance distribution;
- illuminance;
- directionality of light and illumination of the interior space;
- light variability (levels and colour);
- colour rendering and colour appearance of light;
- glare;
- flicker.
Illuminance in the area of the visual task
Illuminance is a basic requirement for perceiving the visual task and performing it quickly, safely and comfortably; it is a quantitative parameter representing the light power density per unit area.
It is a quantitative parameter that represents the density of light power per unit area. We speak more precisely of "average maintained illuminance" values; this term refers to the minimum illuminance value that can be measured when the installation requires maintenance due to the decay of the luminous flux. In fact, due to the reduction of the emission of the sources or to the dirt accumulated on the surfaces of reflectors or refractors, the flux is reduced over time compared to the initial value (new system).
The standard lays down precise requirements for the illuminance of the workstation and the surrounding area. In particular, the following are defined:
- a zone (A) within which the task is carried out (task zone);
- a band (B) surrounding the task zone within the field of vision (immediate surrounding zone). A band of at least 0,5 m around the task area shall be considered;
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a zone (C) adjacent to the immediate surrounding area (background zone). A band of at least 3 m is considered adjacent to the immediate surrounding area.
| Illuminance of visual task area [lx] | Minimum illuminance of surrounding area [lx] | Illuminance of the background area [lx] |
| ≥ 750 | 500 | > 500 / 3 |
| 500 | 300 | > 300 / 3 |
| 300 | 200 | > 200 / 3 |
| ≤ 200 | Same illuminance as the visual task area | Illumination of the visual task area / 3 |
To avoid visual fatigue and discomfort, illuminance should not vary too much from the area of the work task to the immediate surrounding area. For this reason, the illuminance of the surrounding area must be related to that of the area where the work task is carried out; the values recommended by the standard are given in the table.
The background area itself must meet minimum illuminance levels, particularly in environments without daylight.
Luminous flux
Luminous flux" (Φv), or light output, is a measure of the perceived power of light.
It differs from 'radiant flux' (Φe), which measures the total power of the emitted light, in that it takes into account the sensitivity of the human eye to different wavelengths of light.
The characteristic luminous flux, on the other hand, is the initial value of the flux of a lamp or luminaire declared by the manufacturer (or seller) with reference to specific conditions. The luminous flux is measured in lumen (lm).
Illuminance
The 'illuminance' (Ev) at a point on a surface is the ratio of the luminous flux incident on an element of the surface containing the point to the area of the element.
Illuminance is measured in lux (lx = lm x m-2).
Glare
When there are surfaces with high luminance gradients within the field of vision, glare is perceived, a visual sensation that generates fatigue and visual discomfort.
While glare due to an internal light source can be avoided by appropriate shading of the lighting fixture, glazed surfaces (doors, windows, skylights) subject to direct sunlight are screened with movable shading devices such as blinds, shutters or Venetian blinds; for coordinated operation, they should be controlled by the same building automation system that controls the lighting.
Luminous flux
Luminous flux” (Φv), or light output, is a measure of the perceived power of light. It
More information
Illuminance
The 'illuminance' (Ev) at a point on a surface is the ratio of the luminous flux incident on an element of the surface containing the point to the area of the element.
More information
Glare
Glare is a visual sensation that generates fatigue and visual discomfort.
More information
Colour
When talking about the colour of light, the standard considers two parameters:
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the colour temperature (Tcp);
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the colour rendering index (Ra).
| Colour appearance | Proximal colour temperature Tcp |
| Warm | less than 3.300 K |
| Intermediate | between 3.300 and 5.300 K |
| Cold | greater than 5.300 K |
While the appearance of daylight typically varies over the course of the day, the appearance of artificial light is determined by the choice of light source; here we enter the field of psychological research, aesthetic evaluation and the relationship with other choices made for the environment such as the level of illuminance, the colour of walls or furniture.
The emergence of LED light sources and digital control systems offers new opportunities for artificial light: while until a few years ago the choice of source was limited to the colour temperature until it was replaced, there are LED sources that allow this to be changed.
Colour temperature
Colour temperature is an intuitive concept nowadays even for final users who buy LED lamps for home appliances as a retrofit to traditional incandescent or compact fluorescent lamps with standard E27 or E14 socket: the value (expressed in Kelvin degrees) is indicated on the packaging together with a qualitative description such as 'cold light', 'neutral light' or 'warm light'.
In more rigorous terms, the colour temperature is a parameter obtained by comparing it with the luminous variation that occurs when heating a black body; as the temperature increases, the light emission of the body gradually changes from red to orange, to yellow, to white, to blue-white.
The colour temperature of a light source is therefore defined as the temperature at which the colour of the black body corresponds exactly to that of the light source.
Colour
The emergence of LED light sources and digital control systems offers new opportunities for artificial light.
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Colour temperature
The colour temperature is a parameter obtained by comparing it with the luminous variation that occurs when heating a black body.
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Law 626 and Legislative Decree 81/08
While the UNI EN 12464-1 standard provides lighting designers with useful indications to achieve maximum visual comfort and the best visual performance in all safety for people working in working environments, the provisions to be compulsorily observed with reference to the health and safety of workers are the subject of legal provisions.
The reference in Italy has long been Law 626 of 1994, which considered lighting in Article 10 "Natural and artificial lighting of workplaces".
Following the approval of the delegated law 123, Law 626 was replaced by Legislative Decree 81, which led to a simplification of the regulations by creating a single text on safety at work.
References
CEI EN 12464-1 Light and lighting - Lighting of workplaces - Part 1: Indoor workplaces.
Legislative Decree no. 81 of 9 April 2008, Consolidated text on health and safety at work, implementation of Article 1 of Law no. 123 of 3 August 2007 on the protection of health and safety in the workplace.