The difference between the K value and the U value of the energy saving parameters of glass

Now it's possible for people to mix the two values, one of them, so here's a detailed description of them.

Although they are the heat transfer coefficient, but there is difference between the U value and K value, especially when you bid project if it is foreign architects to design it, you must know the difference, otherwise, in the selection of the glass you would make a mistake.

The difference between them is mainly due to the from different standard system, China in glass industry the earliest use of Japanese data, so in the two countries with the same K value, the United States called U, Europe also called K, Chinese standard GB10294, European EN673, American Standard ASHRAE, United States Europe and the U value is not the same, this is mainly due to the test environment is not the same as in Europe, measuring the K value of the external environment temperature is 2.5 degrees centigrade, the internal temperature of 17.5 DEG C, wind speed 4m/s, without direct sunlight (equivalent to night). The United States out of the ordinary, it is winter and summer U value, U value, U value of the test environment in winter as the external temperature is -20 DEG C, the internal temperature of 21 DEG C, wind speed 3.3m/s, and night environment; summer U test environment for the internal external 32 DEG, 23.8 DEG C, wind speed 6.7m/s, the equivalent of the sunlight environment.

According to the test environment above, the relevant heat transfer coefficients of China, the United States and Europe are as follows: the European K value < China K value < U value of the United States

Shenzhen CSG a glass for example, in the case of 6CEB21+12A+6C, the K value is 1.61, China K value is 1.68, the United States winter U value is 1.77, the summer U value is 1.95, but the U value in general use value in winter.

Therefore, when a foreign architect designs a tender document issued by a foreign architect (generally, such a blueprint is made by a foreign architectural design unit), we must clarify its criteria and transform it into domestic value so as not to make mistakes.