Bio Building

Thermal radiation and energy efficiency

L'thermal radiation it is one of the mechanisms for transmitting energy in the form of heat. Its characteristic is that it does not require a physical support for the transfer: heat can be transmitted from the hottest body to the coldest one even if there is a vacuum between them. It is easy to understand that theirradiation it is the mechanism by which the energy emitted by the Sun reaches and heats the Earth. Solar radiation reaches the surface of the Earth after passing through very cold layers of air at high altitudes.

L'thermal radiation it is characterized by wavelengths ranging from about 0.1 mm to 100 mm. Wavelengths that include all the radiation of the visible field (wavelengths between 0.40 and 0.76 mm) and part of the infrared and ultraviolet radiation.

To block the phenomenon ofthermal radiation and increase theenergy efficiency of a domestic heating (or cooling!) system, buildings use special insulating panels. About 40% of the energy currently used in Europe is destined to heat homes and offices: properly insulated buildings consume considerably less energy. The heat of a building is dissipated by conduction, convection and thermal radiation. Thermal insulation based on mineral wool prevent convection by trapping the air and, in addition, also block radiation and limit the conduction of heat.

Thermal radiation because of the "problems" also in the sector photovoltaic: the performance of solar panels can be easily influenced by temperature in fact, like all other semiconductors, even solar cells are sensitive to temperature. An increase in temperature reduces the "band gap" of a semiconductor, thus affecting most of the semiconductor parameters. High values ​​of the temperature cause a reduction in the energy production of a photovoltaic system.

Temperature is a limiting factor for photovoltaics. It is for this reason that in measuring thesolar radiation to estimate the potential capacity of a photovoltaic system installed in a specific geographical area, the effect of the temperature of the photovoltaic cell is also measured. This measurement can be taken thanks to a thermocouple.

Video: GCSE Physics - Conduction, Convection and Radiation #5 (October 2020).