Topic 6-Home Heating Flashcards
What is conduction?
Conduction occurs through solids and liquids. Materials such as metals are very good thermal conductors
How are homes heated?
Homes are heated by transforming energy sources such as electricity or gas into heat using appliances such as electric fires or hot-water radiators. Thermal (heat) energy will move from somewhere hot (where the temperature is higher) to somewhere cold (where the temperature is lower). It does this by conduction, convection and radiation
What is convection?
Convection occurs through liquids and gases. When a gas (or liquid) is heated, the particles move faster. As the particles speed up they get further apart, increasing the volume of the gas. This causes the density of the gas to decrease. Less dense gas will float (or rise) above more dense gas. As the gas rises it cools again, the particles slow down, get closer together, increase in density and fall. This creates a convection current which heats the room. Temperature differences within the Earth’s mantle and within the atmosphere cause natural convection currents
What is radiation?
ThermL radiation is emitted by hot objects. A hot-water radiator emits infrared electromagnetic radiation. Dull, black objects are good emitters and absorbers of thermal radiation. Shiny, light-coloured objects are good reflectors of thermal radiation. All objects emit thermal radiation, but the higher the temperatures of the object the greater the amounts of thermal radiation emitted
What is insulation?
The amount of thermal energy escaping from a house can be reduced by using domestic insulation system that work by reducing the effects of thermal conduction, convection and radiation.
What’s draught proofing?
Draught excluders and draft-proofing strips are fitted, reducing the convection of hot air through gaps under doors and in windows frames
What’s cavity-wall insulation?
Fills the space between the double walls of bricks with foam. The foam traps air, which is a poor conductor and prevents air from circulating within the cavity, reducing thermal loss by convection
What’s floor insulation?
Mineral wool is laid between the joists under the floorboards and silicone sealant is used to seal gaps between skirting boards and floorboards. This reduces thermal loss via conduction and convection
What’s loft insulation?
Mineral wool insulation is laid between the timber joists in the lofts. This reduces thermal loss via conduction and convection
What’s double glazing?
Two sheets of glass with a gap between them. Reduces thermal loss via conduction and convection.
