Globally, humanity is at risk from the coronavirus disease (COVID-19). To address the shortage of beds in quarantining those infected with COVID-19, hospitals have prepared temporary beds. However, for temporary hospital beds, it is difficult to maintain a comfortable temperature due to lack of insulation and heat storage. Phase change materials (PCMs) are used to provide temperature stability and control for temporary structure. Therefore, this study aimed to conduct experiments that analyze the effect of room temperature stabilization using a PCM. The method of macro packed PCM (MPPCM) was used to apply the PCM to buildings. The MPPCM installation location was selected and the effect of reducing the box temperature was analyzed, according to the strength of the heat source. As a result, a maximum reduction of 4.9 °C in the box temperature was achieved. Therefore, the application of MPPCM to buildings give to stabilize the box temperature. And the result showed the possibility of providing a comfortable indoor space for temporary hospital beds.