Surface-area-to-volume ratio

The surface to volume ratio (A / V ) ratio is the ratio of the surface area A and the volume V of a geometric body. It has the dimension 1/length.

For a given volume includes all bodies of the sphere has the smallest surface. With increasing volume of the A / V ratio in all bodies decreases as the square surface, however, the volume grows cubically ( to the third power ). This is important for the cooling rate of different sized masses: The cooling is proportional to the size of the surface, but grow more slowly when becomes larger, than the volume, so that larger masses cool more slowly than small ones. This is also the reason that penguins in Antarctica are larger than their living relatives near the equator; Antarctica Penguins lose their large size, less heat on the relatively smaller surface. In contrast, in warmer areas penguins rely on a better way of heat to escape death by overheating.

Building Physics

In the physics and the heat protection analysis, the A / V ratio is an important parameter for the compactness of a building. It is calculated as the quotient of the heat-transmitting envelope, ie surfaces that give off heat to the environment, such as walls, windows, roof, and the heated building volume. The A / V ratio significantly influenced the heating energy demand. A lower A / V ratio means a smaller heat transferring outer surface with the same volume of the building. Less energy per cubic meter of volume thus necessary to compensate the heat loss through the shell.

Large buildings naturally have smaller A / V ratios, as for example, single-family homes. Typical values ​​for single-family houses are between 0.8 and 1.0 m² / m³. In large, compact buildings values ​​are to under 0.2 m² / m³ possible.

Examples

• Building Physics
• Space geometry