My experience in the US at least is that its not uncommon for the furnace air intake to draw air from inside the house (my last two homes in PNW as one example).
That used to be very common in the US, and there are a lot of old systems still working. However every new furnace I've seen is installed to use outside air. Using outside air needs $100 more in parts and labor and it prevents air balance issues in modern well sealed houses.
The furnace my parents (who live in Ohio) installed 10+ years ago uses outside air for combustion, not conditioned inside air. As it's older, it's not got a 99 AFUE, but it's high (I think in the low 90s).
