This is an extract about testing sleeping bags from a research document produced by the Hohensteiner Institute

Freezing in a sleeping bag?

When purchasing sleeping bags, the most important factor is the minimum environmental temperature at which the sleeping bags can be used without feeling cold. "Charlie 3" (a manikin with heat sensors placed inside the sleeping bag, see photo) provides the answer to this question. He is used to measure the effective thermal insulation of the sleeping bag for the sleeper in a climatic chamber under defined conditions.

Thermal Range of Sleeping Bags

In an extensive research project, scientists at Hohensteiner developed a physiological evaluation model in the early 1990s that could be used to derive the thermal range of utility of a sleeping bag from these thermal insulation values. The lower limits for sleeping bags were
the "comfort" and "limit" temperatures at which the "standard woman" or "standard man" begins to feel cold in the sleeping bag. At the even lower "extreme temperature", the "standard woman" would suffer from hypothermia. The "maximum temperature" at which the sleeper sweats excessively in the sleeping bags forms the upper limit for the range of utility of the sleeping bag.

Sleeping Bag Temperature Information

This measuring and evaluation method was incorporated in the German standard DIN 7943-1 in 1995. This was replaced in 2002 by the European standard EN 13537. Sleeping bag manufacturers are now able to provide temperature information for their products on an objective and scientifically proven basis and are no longer dependent on pure speculation. Many sleeping bag manufacturers or retailers therefore have their products tested at the Hohenstein Institutes. These tests are now particularly significant, as the Product Liability Act passed throughout Europe in 2005 makes the sleeping bag manufacturer liable for the accuracy of the thermal limits stated for the range of application.

Gelert Sleeping Bag Temperature Ratings

Gelert have three sleeping bag ratings; Extreme, Comfort and Season.

The sleeping bag extreme temperature rating is the lowest temperature at which the bag will perform.

The sleeping bag comfort zone indicates a temperature range making sure campers feel comfortable throughout the night.

Sleeping bags can also be catagorized into seasons. These are a guide to supplement the temperature ratings.

If there is no temperature rating on the sleeping bag, then the bag has not been tested at the Hohensteiner Institute. Assume these sleeping bags are for summer use, caravans, or indoor sleepovers.

Gelert Sleeping Bags Link