c It is the door and window product with the lower heat transfer coefficient among the three door and window products. When the K value of doors and windows under the new standard requires 2.0~1.5W/m².K, the market price of plastic windows and broken bridge aluminum alloy windows will be doubled on the basis of the original standard, while the market price of aluminum clad wood doors and windows will be doubled. Just a slight increase. This is because for aluminum-clad wood doors and windows, this indicator is currently the conventional product of wood windows in my country. When the K value of doors and windows is required to be 1.5 ~ 0.8W/m².K, the cost performance of wooden windows is getting higher and higher as the K value decreases. Broken bridge aluminum alloys are relatively expensive to achieve a lower K value, especially in cold regions, such as Finland, Denmark and other countries in northern Europe, where the market share of wooden windows exceeds 70%, which is also the current European market for civil buildings. Reasons why aluminum alloy windows are rarely used. The 68 series and 78 series aluminum clad wood windows produced by Weidun Aluminium Clad Wood Windows and Doors Co., Ltd. can meet the requirement that the K value is less than 1.5W/m².K, and even the requirement below 0.8W/m².K, which meets the German standard. Passive house indicators