Heat sinks are often located in the floor of a greenhouse, typically lined with bricks or filled with sand or fine gravel. Any mass that reduces air pockets is appropriate. Alternatively, any kind of dense mass, preferably dark in color, is adept at absorbing heat. Large barrels of water, painted black, are very typical examples of heat sinks or thermal batteries.
Heat sinks are also used to help cool spaces. As the heat sink passively absorbs heat, water pipes or other cooling mediums may be routed around or through the heat sink to carry the heat away. The effectively converts the heat sink to an active cooling mechanism.
