For temperature ratings, NANGA utilizes the European Standard (EN), which is a uniform standardization system of the EU.
EN (European Norm) is the name of the uniform standard that has been established in the European Union. It is also called the European Standard. The European Standard, EN13537 specifies the requirements to determine the temperature ratings for sleeping bags. Until recently, manufacturers were providing temperature ratings by their own methods; however, the ratings are now determined based on unified criteria. The tests are conducted by authorized third parties for fairness, drawing a sharp distinction from temperature ratings provided by the manufacturers based on their individual standards.
EN 13537 Testing Method
A mannequin installed with temperature sensors is dressed in long sleeves and underwear down to the ankles, then laid inside a sleeping bag on top of a camping mattress. Temperature is measured at 5 locations inside the mannequin in addition to measuring heat radiation levels. The measured temperatures and the room temperature in the laboratory are plugged into an equation to produce a value. A sleeping bag's ability to retain warmth is affected not only by the amount of filling but also by the accessories, like zippers, as well as the type and thickness of the fabric. All of these factors are evaluated comprehensively in the test.
