THESE NOTES DESCRIBE GENERAL PRINCIPLES BASIC TO ALL PASSIVE SOLAR SYSTEMS INCLUDING IMPORTANCE OF A RECTANGULAR HOUSE WITH A MAXIMUM WALL AREA FACING SOUTH; THE USE OF WINDOWS AND OR/GLASS OR SUITABLE TRANSPARENT MATERIALS TO TRANSMIT SUNLIGHT TO THE INTERIOR; THE DESIGN OF A BRICK THERMAL STORAGE SYSTEM; THE RE-RADIATION OF THE COLLECTED HEAT TO THE LIVING SPACE AND THE HEATING OF THE BUILDING BY CONDUCTION, RADIATION, AND CONVECTION; AND THE USE OF A SUMMER SUNLIGHT SHADING DEVICE. OTHER DESIGN CONSIDERATIONS ARE NIGHT INSULATION AND LIMITED OR NO WINDOW SPACE OR NORTH, EAST, AND WEST WALLS. DIRECT GAIN SOLAR SYSTEMS, WHICH RELY ON BRICK MASONRY EXPOSED TO SUNLIGHT TO HEAT THE HOUSE INTERIOR, ARE ECONOMICAL BUT SUBJECT TO FLUCTUATIONS IN TEMPERATURE AND CAN CAUSE FURNISHINGS TO DETERIORATE. THERMAL STORAGE WALL SYSTEMS USE SOUTH-FACING GLASS PLACED 2 TO 4 INCHES OUTSIDE A SOLID BRICK WALL 10 TO 18 INCHES THICK. WINTER SUNLIGHT, TRANSMITTED BY THE GLASS, PENETRATES THE WALL BY CONDUCTION AND IS RADIATED TO THE INTERIOR. IT TOO IS ECONOMICAL, ALTHOUGH INSTALLATION COSTS MAY BE SLIGHTLY HIGHER. TEMPERATURE FLUCTUATIONS ARE SMALLER AND FURNISHINGS DO NOT DETERIORATE. AN IDEAL SYSTEM WOULD COMBINE BOTH DIRECT GAIN AND THERMAL STORAGE IN CONSTRUCTING THE SOUTH-FACING WALL. BRICK MASONRY IS PARTICULARLY USEFUL FOR ITS ABILITY TO WITHSTAND HEAT WITHOUT DETERIORATING AND FOR ITS CONDUCTIVITY, ABSORPTIVITY, SPECIFIC HEAT, EMISSIVITY, COLOR, AND MASS. DIAGRAMS AND REFERENCES ARE GIVEN. (AOP)