Optimal design of a solar and geothermal system for improving the indoor thermal environment of temporary houses in cold climates

Temporary prefabricated houses (TPHs) have been widely used as emergency shelter to protect the disaster-affected people from the surrounding harsh climatic environment. However, the TPHs face the issues of low indoor temperature and inadequate ventilation in cold climates. This study investigated and maximized the performance of a novel passive solar and shallow-geothermal system in order to effectively deliver fresh air and improve indoor temperature for TPHs in cold climates. A full-scale experimental platform was established in Xinjiang Uygur Autonomous Region of China, and the local weather is characterized by long and severely cold winter. Short-term field measurement indicated that the proposed heating system effectively elevated the indoor thermal environment of the TPH, and the average indoor air temperature was 5.0 °C. Furthermore, a numerical study was performed to maximize the system heating performance. After the entire heating season operation, the average soil temperature was increased by 0.7 °C, while the outlet air temperature was increased by up to 28.5 °C compared to outdoor air temperature. The average indoor temperature was increased by 5.4 °C. More importantly, with the optimized system operated continuously, its performance became more pronounced. The increment in average daily indoor temperature changed from approximately 3.5 to 7.1 °C from early heating season to late heating season.