You need to exchange air in some way or another. If you do, that means heat is removed from the building in winter, which you then need to replace. This means energy use. What FTX does is use the old air to preheat the fresh air from outside. You can also use "frånluftsvärmepump", which instead heats water for the heating system with the energy from the air before it's expelled outside. This is typical in many new smaller houses.
Older houses with "självdrag" works on the principle that there's a difference in temperature between the inside and outside, creating a draft. Still, energy is removed when it's cold outside. The problem with this system is that ventilation increases when it's cold outside, removing more heat, and decreases when it's hot, not removing enough air. You'll therefore need to open the windows. Ventilation in bathrooms has a tendency to be somewhat too low for how much moisture is generated by modern behaviour. Especially in villas without "ångspärr" this can also lead to moisture getting into the attic and condensating onto the inside of the roof, in the long run resulting in mold.
Then you really need to check, since mechanical ventilation can be found in many old houses as well. Even those from the 50's may have had "mekanisk frånluft" since new, though usually only in bathrooms änd kitchens. Right now I'm in one from the 30's which has it as well. In this case the noise travels down the chimney to the fireplace, granted it's not in the bedroom. A much bigger problem is constant noise from neighbours, both in the house itself and neighbouring ones. People simply can't behave. They throw parties which lasts half the night, walk on their heels even in the middle of the night, slam doors, drawers etc shut which creates noise almost 24/7. I've completely given up. The only sure way to fall asleep is earplugs. I'd take slight noise from the ventilation system any day. To add to this there's a fountain which creates a lot of noise 13 hours per day more than half the year... You might be lucky, but don't count on older buildings being better just because they lack FTX. You might find they're worse if you're unlucky. Even if you're lucky someone might move out and another one move in... And one more thing: almost constant renovations, especially bathrooms, might drive you mad very quickly. This normally doesn't happen in new buildings at the same rate, since everything is new.
(And just now, someone slammed the door to the elevator shut with a loud bang... An elevator which had some worn out bearing earlier, creating noise for months on end every time someone used it, which of course, spread all along the elevator shaft.)
