Here is some info that may help you understand the temp ratings on these bad boys.
How are Sleeping Bags tested to determine their Rating?
The conditions covered when rating sleeping bags, range from the upper temperature limit that is most commonly found in the middle of summer to the lowest limit, which could be experienced in the colder season. Hi-tech sensors are used to test sleeping bags, which determine the comfort zone to allow for the best night’s sleep possible. Certain factors have to be taken into consideration when testing sleeping bags for optimal comfort. Such factors include gender, weight and level of fitness.
Women are more susceptible to the cold than men and as a result will need to keep themselves warmer. Naturally, women will have different requirements to men when it comes to choosing a sleeping bag. Some manufacturers’ make sleeping bags with the female body in mind; they feature a wider hip area and a smaller area for the shoulders. They are also on average shorter in length than sleeping bags for men.
The shape of a sleeping bag is important as the right design will retain as much body heat as possible for optimal comfort. For maximum efficiency the best sleeping bags are tapered at the bottom to prevent cold air from circulating around the feet. Sleeping bags designed for cold weather feature a cover at the top to protect the head from the cold.
Another important piece of information is the seasons rating which helps you to buy a sleeping bag for the right time of year. For peace of mind, information on the comfort and warmth of the sleeping bag is given in relation to the time of year for which it has been designed for.
What are the Temperature Ratings?
To help you find the correct sleeping bag for the desired event, a temperature guide is typically found alongside the season ratings. This means that you can buy a sleeping bag, with full confidence that it will be suitable for your needs. The EN 13537:2002 European testing standard is a guide to comfort and rates extreme temperatures. The criteria involves a measure of four temperature ratings:
Upper limit looks at the highest temperature a man can comfortably sleep without too much sweating.
Comfort: this tests the temperature at which a standard woman can comfortably sleep while in a relaxed position.
Lower limit: The temperature at which a man can sleep in a curled position for eight hours.
Extreme: This looks at the lowest temperature at which a woman can survive without risk of hypothermia.
First, you need to determine what time of year you will be needing to use your sleeping bag:
1 season: summer
1-2 seasons: Late spring – summer through to early autumn.
2-3 seasons: spring to autumn
3-4 seasons: spring to winter
5-6 seasons: winter and mountain trekking
From globetrekker.com
