I've got a 4 year old daughter with an asthma problem. We've discovered that if she gets a cold at a time of year when the house is shut up (using furnace or AC) it will trigger a violent cough that lasts for weeks and requires extensive medicating to control (and sometimes not even that will do it). However, if she gets ill when the house is open (mild weather) the cough doesn't occur. We've also had it happen when traveling to relatives' homes, so I don't think it's just our house. We have discovered that we can stop the cough by keeping windows open (even in below zero weather!).
We're about to purchase a house that was built in the 1920's, and it has a 1950's era furnace. We're replacing the furnace (gas, forced air) adding AC, replacing all the windows for efficiency and quiet, and putting on a new roof. I'm concerned that this will seal the house even more and make the problem worse.
Any advice about how to make sure fresh air is circulating? Any information about Air to Air Exchangers? We want to be as green and efficient as possible, but that seems antithetical to the Air to Air Exchangers. Thank you for any help you can provide.