Use of Underground Constructions Enhanced with Evaporative Cooling to Improve Indoor Built Environment in Hot Climate

Underground constructions (UGCs) have been used globally to accommodate a wide range of building usage, such as offices and shopping malls. Most of these constructions suffer from a lack of natural ventilation as well as daylight, as they are completely built under the surface of the earth. This has caused many issues related to discomfort, impacting the activity and the productivity of users. This study aimed to analyse the effect of the use of UGCs in hot regions, enhanced by partly elevated external walls which reach aboveground to ensure natural ventilation and daylight, with relatively small amounts of glazing to minimise the influence of solar heat gain. The study used a real built underground room with field measurements for indoor temperature and relative humidity. Moreover, the study used the computer tool EDSL TAS to simulate the performance of the model throughout the year after a field validation. It was concluded that the use of UGCs in hot climates should be encouraged as natural ventilation and daylight can decrease temperatures by 3 degrees C in summer, and the utilisation of evaporative cooling can cool the indoor environment by nearly 12 degrees C. Furthermore, heat transfer was highly affected by the external environment. It was found that the amount of heat transfer doubled in comparison between under and aboveground constructions. The use of small windows for ventilation caused high humidity, even in hot regions, during summer.

Automated summary

This study analyzed the use of UGCs in hot regions, showing that by enhancing external walls aboveground to ensure natural ventilation and daylight, temperatures can be decreased by 3 degrees C in summer, with evaporative cooling further cooling the indoor environment by nearly 12 degrees C. Heat transfer was found to be significantly affected by the external environment, with a doubling of heat transfer in underground constructions compared to aboveground. Small windows for ventilation in hot regions during summer led to high humidity levels.