The first thermal regulation was adopted in 2000 and now is going to be published the second phase concerning the thermal requirements of the building envelope elements (windows, walls and roofs). Although the existence of the thermal regulation, the social houses in Chile, have enormous deficiencies related with the thermal insulation application, ventilation and condensation [2]. In this context a proposal was prepared, to start in 2006, with the principles and the design guidelines for the social houses rehabilitation [2]. One of the measures proposed consists on the improvement of the envelope thermal quality: roof thermal insulation replacement, inclusion of thermal insulation on the external walls, replacement of single glass by double glass windows. In what concerns the passive solar systems the interventions will focus on solar walls for heating with and without ventilation, solar collectors and accumulator collectors for water heating.