Summer: hot. Winter: cold. If your home suffers from wild swings in temperature, some thermal mass might do you good.
A well insulated home is less prone to wild changes from hot to cold over the course of the day or the year. However, there is another way to moderate a home’s temperature: thermal mass. Thermal mass is a part of the house that is used to store and radiate heat energy.
What is thermal mass? It’s a material that’s used for energy storage in hot and cold climates. Materials that are used for thermal mass include adobe, clay, mud, sod, rammed earth, concrete, wood, and containers of water. Arranging these materials in and around your home in a strategic manner allows them to store and then radiate heat.
How does cold climate thermal mass work? Even when the climate is cold in the winter, the sun still gives energy to the earth. Also, when your home heating system comes on, this energy also heats the home. These two sources of heat energy warm the thermal mass in the building. The thermal mass stores the energy and releases it back into the building during the night. Think of this thermal mass as a large hot water bottle. You fill the bottle with water and use it to provide a slow, steady release of heat over time.
It is best to have the thermal mass directly exposed to the sun in order to absorb heat. The exact amount of thermal mass required to heat a building varies from place to place and from building to building.
The size of the thermal mass you need to keep a building warm depends on the type of thermal mass you install, since different materials store energy to a greater or lesser degree. The amount of thermal mass you require also depends on the amount of heat lost from the structure. As a general rule, the area of thermal mass that is exposed to the sun should be about six times the area of windows that are exposed to the sun. A room with two windows of three square feet each has an exposed area of 6 square feet. This means that the same room would require 36 square feet of thermal mass in the form of a wall or a floor.
In hot climates, thermal mass is also useful for cooling purposes. Houses made out of adobe are the historic form of house construction. These houses have an exceptional ability to use thermal mass to control the home’s temperature. In the daytime, a desert environment is very hot. At night, it becomes cooler. An adobe house has thick walls that prevent heat from entering the building during the day. At night, the walls move the energy back out into the air, preventing the house from becoming too hot.
While we all know about insulation, the use of thermal mass is no less powerful – it’s just less known. Keep your house at the right temperature by using thermal mass moderate the heat in your home.
Image Credit: [jesuino]