A greenhouse is a sunny room where the walls and roof are made from transparent materials. In comes the sunshine to warm up the room and help the plants inside the greenhouse to grow. But what happens at night, when the sun sets? Doesn't it cost a fortune to heat a room made from glass panels? Won't the power or electric bill soar? One way to heat the room efficiently is to collect the solar energy or heat during the daytime, using a solar heat sink. The sink can be a mini-basement of sorts, built below the floor of the greenhouse, filled with a material that absorbs the heat from the sun. When night falls, the heat rises from the solar heat sink and warms the room. A variety of materials can be used in the heat sink to collect the heat, including:
Stack water filled drums in the heat sink. Paint the drum a dark color to better absorb the heat.
Pour a concrete slab over a layer of rocks.
Contain a pile of rocks in wire mesh.
Build a bin and fill it with rocks.
Fill plastic jugs with water and stack them on shelves.
Use concrete filled pumice or cinder blocks.
Insert plastic bags, filled with water, into the cavities of concrete blocks.
Build a structure of brick, adobe or stone.