 According to data collected in the winters of 1975-1976 and 1976-1977, the Trombe wall system reduced the heating costs respectively by 76% and 84%.Unlike an active solar system that employs hardware and mechanical equipment to collect or transport heat, Trombe wall is a passive solar-heating system where the thermal energy flows in the system by natural means such as radiation, conduction, and natural convection.As a consequence, the wall works by absorbing sunlight on its outer face and then transferring this heat through the wall by conduction.