You may need to choose the glass product according to the local building regulations. Normally in the north region of China, it is cold and severe cold area, then the lower U- Value becomes the most important factor for you when choose the glass. For example, the SGG PLANITHERM is most popular in north regions, with higher Light transmittance, and lowest U-Value=1.16 w/m2.k (with 6+16Ar+6). 

Or in severe cold area, the triple double glazing unit with low-e coating is also one of the best solution for enery saving.