I live in a house in Charlotte NC with an upstairs room. Last July during an extremely high heat index/100 degree period I notice a strange smell upstairs. It was a sweet pungent odor and it became stronger has the heat index rose. It almost has a funeral home type formaldehyde smell. Here's link to someone that has the same smell upstairs. Any ideas. The house is about 7 years old. Thanks.

http://en.allexperts.com/q/Indoor-Air-Quality-3586/2008/7/Odd-smell-upstairs.htm

I have never ever smelled formaldehyde in a funeral home. They go to great lengths to make sure that no odours reach anywhere where people are greiving. Otherwise, what would be the point ? In fact, I don't think that chemical has an odour. If funeral homes were not diligent, then it would not be a chemical you would be smelling. A dead animal, dead human has a sickly sweet smell.

You could have some dead animals in crawl spaces, bats, squirrels, whatever, so your job is to find these carcasses and get rid of them, to get rid of the odour.

Or, hire someone to do it.

No thanks, won't open your link.
Tick

Sweet pungent = dead animal.
Funeral home smell might be ammonia. That could be from urine from live animals. It could also just be from death.
Live ones you can usually hear making a racket, unless there's a lot of insulation.