A thermal comfort and health study of naturally ventilated dwellings in Central Mexico

: (Alternative Format Thesis)

Abstract

The UN indicates in its Sustainable Development Goals the right to good health and well-being. Consistent with this goal, the World Health Organization (WHO) published a series of recommendations that promote healthy homes aiming to reduce the risks of poor health in its occupants. However, this is not the case for nine million Mexican families whose housing conditions are reported as poor or in need of improvement. There is a correlation between cold internal environments and respiratory and cardiovascular morbidities, being these two the leading causes of death in Mexico before the COVID19 pandemic. In addition, it is known that countries with mild winters have higher Excess Winter Deaths than countries with severe. This may be because the relatively benign climate reduces the seriousness of this problem, coupled with a lack of adequate building regulations, or they exist but are not enforced.
In fact, poor regulations seem to be the factor that differentiates the mortality and morbidity rates seen in countries with mild and severe winters. Hence, this study begins with a comparative study of the different green building regulations in the largest Latin American countries. As expected, it was found that in the largest countries such as Mexico, Brazil and Argentina, there are regulations that seem adequate not only towards a building's thermal balance but also towards its sustainability. However, these are not enforced, unleashing the problem of houses with poor environments in the region.
To study this issue, a thermal comfort study was undertaken in 26 houses in the central Mexican Plateau, one of the coldest areas in the country. The research included temperature and relative humidity sensors simultaneously monitoring 26 houses during 11 continuous months within the Meseta Central Mexicana (Central Mexican Plateau). At the same time, home visits were made, where I sought to capture the characteristics of their homes and the physical characteristics of our subjects, socioeconomic, health, thermal comfort, and adaptive habits to extreme temperatures, both hot and cold. The visits aimed to identify the relationship between the subjects to their homes and how their internal environmental factors affected their perception of thermal comfort and their self-perception of physical health.
The study found that the population in the plateau area is better adapted to warm temperatures. This was verified thanks to the readings provided by the sensors, which were matched against the thermal comfort surveys. The opposite was observed in winter, where the number of votes within the comfort range dramatically decreased, coupled with low percentages of hours within the comfort bands according to the adaptive method, suggesting a significant thermal discomfort in cold climates in the area.
As a result, it was decided to analyse this cold discomfort in more depth through a proposed underheating model and simulations under different retrofitting scenarios, including ones under the Mexican standard NOM-ENER-020. It was found that under the NOM-020 parameters, the simulated models provide a more significant number of hours within the adaptive comfort bands, as well as a drastic reduction in underheated hours. In addition, the self-perceived health status of our respondents was evaluated against the PPD index. It was found that the greater the thermal dissatisfaction, the worse the self-perceived physical and mental conditions.
This thesis demonstrates that active enforcement of the existing regulations in Mexico, and potentially in the Latin American region, can improve people's quality of life, coupled with the quality of their physical and mental health.

Date of Award	25 May 2022
Original language	English
Awarding Institution	University of Bath
Sponsors	Consejo Nacional de Ciencia y Tecnologia
Supervisor	Sukumar Natarajan (Supervisor) & Ian Walker (Supervisor)