Permeable pavements offer a solution for rainwater runoff treatment in urban areas, combining water management with water reuse purposes when the sealed subbase become rainwater reservoirs. Furthermore, the thermal behavior investigations of these systems have proved their contribution to palliate the urban heat island effect in the hottest season and to delay freezing during the coldest season. Increasing knowledge of heat-transfer mechanisms into the permeable pavements and their subbase has enabled the use of these structures combined with ground source heat pumps (GSHP) in addition to the other well-known applications. The aim of the present study is to investigate the thermal response observations of permeable pavements under specific weather conditions while paying attention to the temperature distribution in the subbase, where rainfall water is stored for others uses, to evaluate the possibility of introducing GSHP technology. The bedding layer and subbase temperature of reinforced grass permeable pavements was monitored during three months in summer 2008, and the preliminary results obtained show the subbase temperature different from the air temperature during the period of the study and demonstrate that the subbase is less affected by the air temperature than the bedding layer because of the insulating capacity of permeable pavements, explained through the heat-transfer processes that take place into the pavements.