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Design and Development of a Nearable Wireless System to Control Indoor Air Quality and Indoor Lighting Quality

ABSTRACT

The article describes the results of the project “open source smart lamp” aimed at designing and developing a smart object able to manage and control the indoor environmental quality (IEQ) of the built environment. A first version of this smart object, built following a do-it-yourself (DIY) approach using a microcontroller, an integrated temperature and relative humidity sensor, and techniques of additive manufacturing, allows the adjustment of the indoor thermal comfort quality (ICQ), by interacting directly with the air conditioner. As is well known, the IEQ is a holistic concept including indoor air quality (IAQ), indoor lighting quality (ILQ) and acoustic comfort, besides thermal comfort.

The upgrade of the smart lamp bridges the gap of the first version of the device providing the possibility of interaction with the air exchange unit and lighting system in order to get an overview of the potential of a nearable device in the management of the IEQ. The upgraded version was tested in a real office equipped with mechanical ventilation and an air conditioning system. This office was occupied by four workers. The experiment is compared with a baseline scenario and the results show how the application of the nearable device effectively optimizes both IAQ and ILQ.

HARDWARE AND SOFTWARE OF THE DEVELOPED NEARABLE

Figure 1. Hardware layout in a real case study

Figure 1. Hardware layout in a real case study

The hardware and software elements of the system are defined using typical concepts of the DIY philosophy: wireless communication, low cost hardware and 3D printed parts. The system is split in two parts (Figure 1): a monitoring station placed near the workstation (nearable monitoring station) able to assess the exact level of illuminance and air quality, and a wireless receiving station (actuation station) connected to the nearable monitoring station that manages the actuation of both the air exchange system and the lamp. Both parts have small dimensions and weight, in order to be adjustable and to minimize their impact on human activity, especially in workplaces.

Figure 3. Predicted mean vote (PMV) preliminary analysis for a typical day of the test period: 26 May from 9:00 a.m. to 6:00 p.m

Figure 3. Predicted mean vote (PMV) preliminary analysis for a typical day of the test period: 26 May from 9:00 a.m. to 6:00 p.m

The chosen sensor covers 60% of the total cost. Unlike the previous case, in the upgraded version of the smart lamp, the thermohygrometric sensor is not installed because a preliminary analysis made up combining the Energy Plus results with Honeybee pre/post processing capabilities (Figure 3) showed an approximated average neutral value for the thermal comfort, expressed by the predicted mean vote (PMV) index. This has suggested the possibility to neglect the control of thermal comfort.

CASE STUDY AND METHOD OF EVALUATION OF COMFORT

Figure 7. 3D representation of the geometric model used for the computational fluid dynamics

Figure 7. 3D representation of the geometric model used for the computational fluid dynamics

The installation of the air exchange system can be a cause of discomfort. The reduced distance between the points where the fans and the workstations were located, could lead to a reduction in terms of indoor comfort due to two effects: an increase of both sound pressure level and air speed. Before the testing period an analysis was made to verify the local discomfort based on user feedback and computational fluid dynamics (CFD) analysis. None of the four workers reported situations of acoustic discomfort. In Figure 7 the black dots are located at a height equal to that of the head of a seated workers, at about 1.3 m.

Figure 10. Hourly average data for manual control (period I, 23–29 May) and automatic control

Figure 10. Hourly average data for manual control (period I, 23–29 May) and automatic control

For ILQ evaluation, the main standard is EN 12464-1:2011 [ 50 ] which defines the minimum required levels of illuminance (lux minimum) to carry out specific indoor activities. For writing, reading and data processing, the main activities performed in the office where the experimentation was conducted, the minimum illuminance value admitted is 500 lx (tagged as “limit” in Figure 10).

EXPERIMENTATION RESULTS

Figure 11. Hourly average data for manual control (period I, 23–29 May) and automatic control

Figure 11. Hourly average data for manual control (period I, 23–29 May) and automatic control

Figure 11 shows the hourly average values of the CO2 concentration. The dates 28–29 May and 4–5 June correspond to Saturday and Sunday, while 2 June is an Italian national holiday (Italian Republic Day). The analysis of CO2 concentration (Figure 11) shows a marked improvement after the adoption of the nearable control system: in period I, during working hours, hourly average values with maximum values close to 2000 ppm were recorded, in any case higher than the 900 ppm limit.

CONCLUSIONS

The developed system demonstrates that a nearable system designed and realized starting from the maker movement philosophy and DIY approach is suitable to ensure good levels of both IAQ and ILQ. The analysis conducted so far demonstrates how it is possible to optimally manage the indoor environmental comfort using some electronics components and a 3D printer. The potential of this basic device is confirmed by tests in real working conditions. The characteristics so far described and analyzed allow a wide field of application aimed at improving users satisfaction and optimizing energy consumption of buildings.

As shown above, the advantages of implementing a system based on a DIY approach with respect to commercial systems are associated with better customization and adaptation options, thus allowing a hacking of a common object, making it capable of carrying out smart operations in order to make the indoor environment more comfortable. In this context, the user is not limited to the passive role of consumer, as he acts as prosumer, actively participating in the various phases of the management and improvement of the environmental quality of the building where he lives. As calculated in the previous paragraph, the solution could be economically favourable if it is considered a complete station able to control ICQ, IAQ and ILQ.

Source: University of Liege
Authors: Francesco Salamone | Lorenzo Belussi | Ludovico Danza | Theodore Galanos | Matteo Ghellere | Italo Meroni

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