*6.3. Users' Evaluation*

Once the application was developed and had passed through a practical validation, the next step was to perform a validation from the point of view of the user. To perform this evaluation, an experiment where 20 subjects tested the tool was conducted. To be sure about the developed application being easily understood, the selected users had different levels of knowledge about lighting analysis.

During the first step of this evaluation, the application was given to users in order to check the lighting quality of their workspaces. Once the users finished the evaluation, they had to fill out a Likert scale questionnaire (1 to 5) [41] of 9 questions with several questions to evaluate and give their opinion about the application.

Analyzing the results of the questionnaire, it is important to highlight how users qualified the complexity of use of the developed tool as medium, even when users had little knowledge about lighting analysis. Regarding the interoperability with the interface, users marked the application with a 4.37, highlighting the easy use of the application. When they were asked about the reason for their answer, 60% of the respondents highlighted how the interface and the messages shown in the application helped them to use it correctly, rating with a 4.47 the accessibility of the information.

Regarding the question about whether the proposed mobile application reached the aim of easing the measurement of work space illuminance, it was punctuated as 4.72. On the other hand, when asked if the developed application was handy to have as a reference about the level of compliance of the European Standards EN 12464-1 [9] and EN 12464-02 [10], the respondents answered affirmatively with a mark of 4.62. To conclude the questionnaire, the respondents were asked if the recommendations given by the application improved the working lighting environment, which users marked as 4.47.

### **7. Discussion and Hypotheses Validation**

At a methodological level, this work contributes with the presentation and the implementation of an engine of rules that facilitates decision-making in an efficient way, telling users if the lighting complies with the European standard and, in the case of deviation, indicating the value of this.

Regarding the hypotheses proposed previously, they can be answered thanks to the research performed in the study. As for the first hypothesis (H1), which stated that the usage of mobile applications could help in disease prevention, it has been observed along the study that this tool eases occupational health and safety prevention related to lighting. This is possible due to the developed application allowing users to evaluate their lighting levels regarding the task that they perform in the evaluated area, allowing them to obtain a better working environment, and preventing at the same time the possible damage derived from bad illumination. Analyzing the studies performed on real scenarios, it is possible to observe that, in most cases when the lighting has been improved, the users noticed the changes in the lighting and also recognized the improvement of the lighting. This feeling is higher in the case of offices, where 53.84% of users saw the improvements, also recognizing having less eye problems once the lighting requirements were improved.

Regarding the second hypothesis (H2), we can assert that the use of mobile applications may help on energy saving as was probed along the practical evaluation of the tool. It must be taken into consideration the power of this sort of application not only in the evaluation of the measurements, but also in giving tips to improve them. In the case of the application developed, the tips shown in cases of noncompliance of the regulations assisted in the improvement of the lighting quality as well as in the reduction of energy consumption. If we analyze the corrections performed in the cases of study, the results highlight a reduction of energy consumption thanks to the tips offered by the application.

In relation to the third hypothesis (H3), which stated that mobile devices can be used as a fairly accurate light meter tool, we can assert that it is not possible. Despite the study highlighting the use of mobiles devices as measurement tools, the process of calibration could be difficult to be performed by any user, as well as necessitate the use of a calibrated luxmeter as a reference, a device that not all users have at their disposal. Besides, the differences of the hardware of each smartphone model makes setting a process of calibration harder. For these reasons, mobile phones should be used as light measurement tools with medium accuracy and should not be used for situations where high reliability is required unless calibrated.

Concerning the fourth hypothesis (H4), which stated that the mobile applications could facilitate the compliance of lighting regulations in working spaces, along the validation of the study's results, it was observed that the use of this sort of application helps in light measuring tasks and gives more information in order to improve the lighting by providing an orientative value by using the ambient light sensor and a measure of quality by using external sensors.

The last hypothesis studied (H5) stated how the use of an intelligent agen<sup>t</sup> based in rules helps in decision-making, providing information to the user. Along the validation, it was observed that the use of rule engines in the mobile applications allows the user to detect the illuminance variation in working spaces regarding the regulations, making it possible to recommend different alternatives to improve the quality of the light.

On the other hand, the use of a rule engine has allowed the development of an intelligent agen<sup>t</sup> based in rules that compares the values acquired by the sensors with the values of the UNE regulations, helping users to adopt the better option to improve the lighting level.
