Radiation depends on surface colour and texture.
· Dark, matt surfaces absorb heat radiation falling on them much more than bright, glossy surfaces, such as whites or silver. They also emit more radiation, at any given temperature.
· Silvered surfaces reflect nearly all heat radiation falling on them.
In reality, this means we would have black solar panels and silver survival blankets.
Making sure heat gets in: e.g. solar hot water panels
1. Solar hot water panels contain water pipes under a black surface (or black painted pipes under glass)
2. Heat radiation from the sun is absorbed by the black surface to heat the water in the pipes.
Making sure heat doesn’t get in: e.g. coolbags