When sunlight falls on a building some of it will be reflected depending upon the colour of the wall:
- white walls will reflect the greatest amount of heat and so traditional buildings in southern Europe generally have white walls to reduce the solar gain in summer
- darker colours reflect less heat but absorb more heat so traditional buildings in northern Europe are often painted red to capture solar radiation.
Heat the flows from the hotter to the colder part of the building through one of three processes:
- conduction through the external to the internal wall of the building
- convection through the movement of air inside a room from the hotter to colder par of the room or by air movement through open windows or doors
Traditional forms of architecture either enhance or reduce heat flows by altering one or more of these flow processes.
