I think you've got the terminology right, we say the exact same thing here in Norway. The difference is just that in Norway, the inside is always the warm side. I'm pretty sure you would do it the other way around in Sinagpore.

Especially if you live in a fairly dry area I guess 30c outside won't make too much of an issue in the summer since it's just 5-10 degrees warmer than the inside which is not much compared to the 50c difference you could get in winter.