Hair Glossary

Calorimetry is a scientific term describing the measurement of heat lost or gained. 

In the long hair community, calorimetry is often defined as a warm yarn or cloth headband, often with buttons or similar style hair-friendly closures. 
A calorimetry headband or hat is designed to prevent the loss of heat from the head or scalp.

These headbands allow you to wear your hair up while keeping your ears warm and preventing heat from escaping from the top of your head.  It usually only requires one skein of yarn to create

Knit hats are a great way to block out the cold. Average calorimetry styled wide knit headbands are a wonderful way to block out the cold and can be designed to be compatible with long hair worn down, in a braid, or in a loose soft bun or chignon.

Calorimetry headbands or hats may also be designed to be stretchy or expandable so that it can be used to still keep ears warm without disturbing a carefully constructed hair bun, braid, or similar protective hairstyle. 
When these headbands are designed with buttons or snaps there is less danger of them disrupting a hairstyle

The Calorimetry style headband is often hand-knitted but may be available in a commercial shop, although may be marketed under a different name

Another name for a Calorimetry-style headband is a winter knit hat.  Men and women of all ages wear these types of heat protective styles.