*3.2. Pedagogic Design*

The objective of the fall 2019 and spring 2020 Smart Energy Challenge, was to verify that randomly selected classrooms at Tecnologico de Monterrey satisfy these requirements for air quality and thermal comfort, and to propose strategies to achieve this at the lowest energy cost in preparation for the return to in-person activities following the COVID-19 pandemic. The challenge required that the students search for the regulations of the specific case, the required instrumentation and, if necessary, its manufacturer. Moreover, the students were asked to implement a detailed plan to generate a baseline, and to compile a database of the rooms´ conditions in terms of temperature, humidity and CO2 concentrations. Finally, with the obtained data and its analysis, the students were asked to propose solutions, considering energy efficiency aspects in conjunction with other aspects, such as thermal comfort and air quality.

An overview of the Smart Energy challenge is shown on Figure 5. The big idea behind the challenge corresponds to the need for decreasing energy consumption in buildings while simultaneously meeting with the comfort needs of their occupants. Students were asked to propose strategies to accomplish this purpose.

**Figure 5.** Use of low-cost sensors to monitor CO2 concentration in classrooms.

An example of the challenge introduction or motivation for the students is presented below. *"In 1982, the WHO defined the sick building syndrome as a set of annoyances and diseases caused, among others, by poor ventilation and temperature decompensation, where at least 20% of the people inside the building feel unwell. More than 30% of the buildings that surround us could cause permanent discomfort to their occupants. If one of its occupants suffers from asthma, allergies, or has respiratory problems, these could be aggravated. The number of bacteria and viruses could increase, even increasing this increases the probability of becoming infected with COVID-19. Reducing the CO2 concentration from 2000 ppm to 1000 ppm increases human efficiency by*

*12% and reduces the possibility of making mistakes by 3%. It is urgent to increase awareness of the importance of indoor air quality and generate real, high-impact alternatives to improve it in Tec's classrooms.*

*People currently spend 90% of their time indoors (homes, workplaces, offices, schools, hospitals, factories, or even shopping centers)* [47,48]. *Therefore, it is necessary to provide satisfactory indoor air quality while guaranteeing the energy-efficiency of the buildings. A healthy environment could be favored by having an adequate Indoor Air Quality (IAQ) level and ventilation system. Airborne virus and bacteria transmission is favored as a result of having poor IAQ, which could generate different health problems* [48].

*The main aspects that influence air quality are vehicle traffic, fuel burning, industries* [47,49,50], *and the low performance of air conditioning systems (HVAC)* [51]. *Carbon dioxide (CO2) from indoor air is one of the critical factors in determining IAQ* [47,52–55]. *In the outside ambient air, CO2 varies typically between 250 ppm and 350 ppm. The CO2 in the indoor air must be below 1000 ppm to avoiding negative impacts on the occupant's health* [48,56,57].

*Several works have focused on assessing air ventilation on office buildings. However, not enough attention has been paid to school buildings* [58]. *A classroom is a tight space with several people inside, therefore, the air quality can deteriorate over time* [50]. *Students comfort, health and productivity (learning efficiency and attention during classes) could be dependent of the IAQ. This includes a decrease in students' performance, spread of viruses such as SARS-CoV-2* [52] *and different social and economic repercussions* [49,59]. *The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommends to increase natural ventilation, improve central air filtration or other HVAC systems that can be operated for extended hours (24/7 if possible), and the use portable HEPA purifiers. Moreover, having acceptable concentration values of CO2 (at levels established by regulations) ensure the comfort level of the occupants and efficient energy consumption* [60].

The objective of the smart energy challenge presented to the student is the following:

*"Evaluate the indoor air quality under different ventilation conditions according to international regulatory standards and assessing CO2 concentrations. Offer proposals to improve the air quality in classrooms as well as energy savings."*
