Heat is the flow of energy from a warm object to a cooler one. This is called heat energy.

All matter is made up of particles and all particles have heat energy. Heat energy is everywhere and in everything!

Particles also have kinetic energy. Kinetic energy is found in movement, and when atoms vibrate or move around, we feel their kinetic energies as temperature.

Particles have more energy at high temperatures, and when this energy passes to an object of a lower temperature, its particles' movement increases, transferring heat energy.

Heat energy continues to transfer from the warmer object to the cooler until they are the same temperature (if the object has enough energy to do so).

Objects of the same temperature reach a state of thermal equilibrium and there is no more heat transfer.

If enough heat energy is transferred, it can break the bonds holding the particles together. This can cause an object to change its state: solid to liquid to gas.

Heat energy can be transferred in three different ways – Convection, Conduction, and Radiation.

Convection transfers heat through the movement of particles.

Particles with lots of heat energy are less dense and rise, they move into cooler areas and become more dense and sink. This pushes particles with less heat energy into warm areas to rise, creating a circular motion.

Conduction is the transfer of heat energy by direct contact.

The heat energy from particles of the warm object increases the particle energy of the cooler object, passing the heat from one object to the other.

Radiation does not rely on particles to transfer heat and can travel through a vacuum, such as space.

Heat energy has been used across the ages to heat huts and homes, using a mix of radiation, convection, and even elements of conduction to supply families with warmth.

The first example of central heating dates back to Roman times. The 'Hypocaust' system heated a void that warmed the space next to or above it.

This type of heating system was abandoned, and for many centuries, the radiation heat from fireplaces was used to keep homes warm.

In the late 18th and early 19th centuries new designs (similar to roman systems) began to use underground passages, ducts, and pipes to distribute heat using hot air or steam.

By the mid-19th century a system was invented that allowed hot water to pass through steel columns, heating the air and the room – the radiator! This set the ground work for modern heating systems.

'Wet' central heating systems can heat radiator water via different heat sources, often through a gas boiler.

Central heating uses key components to heat and circulate the water.

The transfer of heat energy from your heating system to the air means that the energy can escape through windows, walls, or ceilings if it is not blocked.

Insulation helps to retain heat inside the home.

Ancient Egyptians used asbestos for insulation, while Ancient Greek and Roman homes had a cavity wall invention to insulate.

Cavity wall insulation has used many 'fillers', including rock wool and asbestos (until the harmful effects were discovered). Modern homes now use blown mineral fibre and expanding polystyrene beads to insulate.

Today, central heating is a basic requirement in most homes and something we can take for granted - before the 1980s it was considered a luxury and many families still huddled over the fireplace for warmth.

In the modern world, common heating systems can be powered by solar panels, a furnace, heat pump, electricity, and, of course, a boiler.