Pre-Columbian Native American architecture also shows an understanding of passive solar principles. Cliff dwellings made of earth faced south, welcoming the winter sun yet providing protection from direct overhead rays in the summer.
Rammed-earth solar homes use passive solar principles today. Rammed-earth walls 18 to 24 inches thick are made of a mixture of cement, water and earth. This mixture is poured into a form, like concrete. When the mixture has dried, the form is removed. Rammed-earth walls have a high thermal mass, or the ability to store thermal energy. When the sun’s rays enter a room, their heat penetrates and is stored in the walls. This stored radiant energy is then available to help balance any drop in room temperature during the night.