P1- 1.9

Seite 1

P1- 1.9- HEATING AND INSULATING BUILDINGS

Reducing the rate of energy transfers at home:

LOFT INSULATION- Such as fibreglass reduces the rate of energy lose through the roof. The air between the fibre helps to reduce the rate of energy transfer by conduction. Fibreglass is also a good insulator

CAVITY WALL INSULATION- Reduces the loss through the outer walls of the house. The 'cavity' is the space between the two layers of brick that make up the wall. The insulation is pumped into the cavity. It is a better insulator than the air it replaces. It traps the air in small pockets, reducing convection currents

ALUMINIUM FOIL- Between a radiator panel and the wall reflects radiation away from the wall

DOUBLE GLAZED WINDOWS- Have two glass panes with dry air or a vacuum in between. Dry air is a good insulator so it reduces the rate of energy transfer by conduction. A vacuum cuts out energy transfer by convection aswell

U-VALUES:

- Used to compare different insulating materials

- This is the energy per second that passes through one square metre of material when the temperature difference across it is 1 degree Celsius

THE LOWER THE U-VALUE THE MORE EFFECTIVE THE MATERIAL IS AS AN INSULATOR

SOLAR HEATING PANELS:

- Uses solar energy to heat water

- Fitted in the roof

The panel is a flat box containing liquid-filled copper pipes on a matt black plate

The pipes are connected to a heat exchanger in a water storage tank in the house

A transparent cover on the top of the panel allows solar radiation through to heat the metal plate.

Insulating material under the plate stops energy being transferred through the black panel

The metal plate and the copper pipes in the box become hot

Liquid pumped through the pipes is heated when it passes through the panel

The liquid may be water or a solution containing antifreeze

The hot liquid passes through the heat exchanger and transfers energy to the water in the storage tank