Read the evidence

The competition hall uses several sources of thermal energy. Sunlight transfers energy to the roof and floor by radiation. A wood stove releases energy when wood burns in oxygen; this chemical reaction is combustion. Deep underground, hot rock can warm water, producing geothermal energy. In a compost pile, decomposers break down organic matter and release some energy as heat. Heat can move from a warmer place to a cooler one by conduction, convection, or radiation. These sources are not interchangeable: sunlight and geothermal energy are natural energy sources, while combustion and decomposition are processes that release stored chemical energy.