The latest burning technology for enhanced efficiency With an efficiency of 86% it has all the features of both the Aire 5 and Aire 7: large ceramic glass window, single air control for easy use, cool-to -touch handle for safe reloading but perhaps best of all it meets all the criteria set for Ecodesign 2022 with a Clear Skies rating of 5 stars. This is quite revolutionary for a stove with such a small output.