Passive solar heating takes advantage of the natural heat of the sun. Windows or other openings are placed on the south side of a building so that the sun can heat the building in the winter. Thermal mass, such as a brick wall, can be used to store the heat and slow the release of heat into the building. In this design, the greenhouse is oriented so that the long side of the building is facing south. This will allow the most direct sunlight to enter the building. The windows on the south side are larger than the windows on the other sides, and they are also positioned higher on the wall so that they can capture more sunlight. The roof of the greenhouse is also sloped so that it will direct sunlight into the building. In the winter, the warm air inside the greenhouse will rise and escape through the roof, and the cold air will be drawn in through the windows. This will help to keep the greenhouse warm.