Thermal mass is a heat storage material, such as water, concrete, masonry, or earthen construction, used in solar thermal energy systems also known as passive solar heating systems. With passive solar heating, the house itself acts as the solar collector and the storage facility. The essential elements of a passive solar system are:
- excellent insulation,
- solar collection (with south-facing windows), and
- thermal storage facilities (thermal mass).
Thermal mass and insulation
Types of passive systems
There are three categories that passive systems can fall into:
One of which is a direct gain system. In this system, large south-facing windows are used to admit the sunlight. and thermal mass is placed in the house to absorb the solar radiation. Another system is indirect-gain.
Finally, the third category of these passive solar heating systems is an attached greenhouse on the south side of the house. The greenhouse acts as an expanded thermal storage wall. It will share some of its heat with the adjoining house.