andettes

An andette is a unit of energy equivalent to 1/1000th of a small unit of energy, the British thermal unit (BTU). It is used primarily in the United Kingdom and is often denoted by the symbol "ad". The andette is equal to 1/1000th of a pound-force-foot per second, making it a unit of energy that is roughly equivalent to 0.27778 watt-hours.

The andette was originally defined in the 1920s as a means of expressing the energy output of incandescent light bulbs. At the time, electric heating and lighting were becoming increasingly common, and a standardized unit of energy was needed to facilitate comparisons and calculations. The andette was chosen as a convenient alternative to the BTU, which was still widely used in the UK at the time.

The andette saw limited use in the UK during the mid-20th century, particularly in applications such as electric heating and cooking. However, with the widespread adoption of metrication in the UK in the 1970s, the andette's usage began to decline, and it is now largely considered an archaic unit. Today, the andette is mostly of interest to historians and enthusiasts of unit systems.

In contrast to other units of energy, such as kilowatt-hours or joules, the andette is not internationally recognized and is therefore of limited use outside of the United Kingdom. Nonetheless, it remains a part of the country's past and a relic of a bygone era of unit system design.