I've installed double glazed windows on 2 houses in Chiang Mai. Here is what I've learned that may help you decide ;
- glass was manufactured in BKK. Good quality work. These companies export worldwide so standards are good. Not had issues re condensation between panes in 10+ years
- very good noise insulation - but make sure the 2 panes are different thickness - ie 6mm and 5mm . This reduces resonance of sound waves = better noise insulation .
- heat insulation - air gap of 10-12mm best . Argon gas inside air gap 'apparently' provides better insulation . I've tried argon (B100/m2) but really cant tell if it works. Cant tell if the argon has even been injected or if it has leaked out over time. But in theory, under test conditions , it works . Also apparently provides noise insulation
- heat insulation - if you use aluminum frames with no thermal break - and you have direct sun exposure on the windows - you will get a lot of heat transfer through the frames and onto the inner pane of glass. Thermal break alu frames were expensive when i looked (imported) and not very common here. Thermal break is common in N Europe where you have temperature differentials of 60C or more. In C Mai the differential is only 30C .
- Better frames for insulation are wood or UPVC (many different qualities of PVC so choose carefully) . I've done alu with no thermal break, and UPVC. Next I will try teak wood. You can look up the R value of these 3 and see alu is an excellent heat conductor!!
- Is it worth it ? For me the noise reduction is worth it . The heat insulation will reduce electric bills - how much depends on the window frames and whether you have direct sun on the glass .