**2. Prior Research**

Prior research has been focused on three different areas. The first point shows European regulations that allow the control of the level of illuminance in different areas. The second point shows the existing software solutions for the lighting evaluation, while the last point carries out a brief study about the health problems derived from bad illumination to highlight the advantages of the proposed tool in the health field.

### *2.1. Regulations for Lighting Evaluation*

Artificial lighting has become in an essential service for modern life. There is no doubt about its benefits, because it allows users to increment the activity in spaces without enough quality of light and also creates a welcoming feeling, making it possible to increment the night activity while reducing crime at the same time [15]. Due to its importance in our lives, it is necessary to control it.

One of the aspects where artificial lighting has a high impact is in energy consumption. Only taking into account the street lighting installations, the amount of energy rises up to 2.3% of the global electricity consumption [16]. To control this amount of energy, different countries have set regulations to help to improve the energy efficiency of its installation. It is the case of the Royal Decree 1890/2008 [17] which established, by the Spanish Government, the standard called EN 13201-5 [18] set by the European Union or the British Standard BS 5489 [19], among others.

Despite energy being an important aspect to take into consideration, mostly in outdoor spaces, there are other regulations to control the amount of light in working spaces in both outdoor and indoor spaces. Here is the case of the EN 12464-1 [9] and EN 12464-2 [10] regulations.

The regulation EN 12464-1 [9] specifies the lighting's requirements for most indoor working places and their associated areas in terms of quantity and quality of lighting. In addition, this regulation gives recommendations for a good practice of lighting through qualitative and quantitative satisfaction.

Another important regulation related to lighting requirements is EN 12464-2 [10]. This regulation allows the guarantee that the visual tasks performed in outdoor spaces can be carried out in an efficient way, especially during night time.

### *2.2. Light Evaluation Software*

There are different programs that must be used to evaluate lighting requirements in different kinds of spaces. Most of those programs allow the performance of a quantitative analysis of scenarios, thanks to their capability of creating a 3D virtual world where lighting effects are recreated and analyzed in both artificial lighting and daylighting scenes [20].

One evaluation software that is used in this field is called RELUX. This software allows users to generate quantitative and qualitative analysis of buildings' lighting thanks to simulation models created with specific materials, colors, reflection factors, and natural and artificial lighting elements to ge<sup>t</sup> a closer possible view of reality [21].

Another renowned and well-known tool to evaluate energy efficiency is the SEAD street lighting evaluation toolkit. It can help make better choices regarding street lighting fixtures, which can lead to a maximum of 50% in energy savings [22], by providing an easy way of performing evaluations of light quality, energy consumption, and life cycle costs of efficient street lighting alternatives. This tool is supported by Mexico's National Commission for Energy Efficiency, India's Bureau of Energy Efficiency, Natural Resources Canada, the Swedish Energy Agency, and the U.S. Department of Energy.

Another of the programs used in lighting analysis is called BTwin [23]. It was designed to plan the street lighting installation based on the standard EN 12464-2 [24], as the program can import the manufacturer's luminance information to give more accuracy to the calculations. In addition, an evaluation of the installation's energy efficiency to obtain the energy label before carrying out its implementation can be performed by using the extended feature called AEwin. Vertical obstacles can be considered as well, as they can affect the lighting, and by doing so it is possible to increase the precision of the program.

However, the most important software in this field is called DIALux. The main strength of this software is its complete database about lighting products of the main manufacturers, giving more accuracy to the analysis. It also provides information about power consumption of elements to guarantee compliance with the regulations [25].

### *2.3. Health Problems Derived from Bad Illumination*

Lighting has become one of the most important aspects in efficient building design due to its impact on energy consumption. However, it must be taken into consideration that a good lighting approach should have benefits not only for economic or environmental aspects but also for comfort and health due to its influence on people's quality of life and wellbeing [6,26].

Most office tasks are linked to document processing, whether through paper or digital documents. Therefore, these activities have high visual requirements, making lighting an important factor to prevent discomfort and vision problems.

One of the main lighting problems is derived from over-illumination which occurs due to multiple artificial lights in the ceiling and/or daylight penetrating the room. For example, in a shared space office, the light illuminates not only the cubicle of one worker but also the rest of the cubicles. In addition, the contribution of a light to the light level of the other cubicles is the cross-illumination effect of the particular light. When these effects arise, lighting control requires a regulation between the lights in order to obtain a desired light level across the room [27].

This situation of over-illumination is linked to several negative health effects. Different studies attribute migraine headaches, fatigue, medically defined stress, anxiety, or decreases in sexual function among others to overly intense light [28–31].

Despite most of these symptoms possibly being caused by light that is simply too intense, the color spectrum of fluorescent lighting is another factor that might cause problems, since this sort of lighting is significantly different from sunlight [28,32]. Fatigue is another common complaint from individuals exposed to over-illumination, especially with fluorescent media. For that reason, natural light is preferred over purely artificial light by office workers from both eastern and western cultures [33].
