Now is a good time to check all the vents and venting systems in your home.
The dryer vent - plugged up ones can become fire hazards - also is the outside opening meshed so you don't get uninvited visitors
The air vents for your heating system - some heating systems work better if some are closed or opened when one changes from heating to cooling
The chimney/exhaust systems for your heating method - occasionally birds will build nests in a chimney, are any lines cracked? - carbon monoxide is odorless so one won't smell it if there is a leak or backdraft
The plumbing vents (water won't drain well if they are clogged)- again, things can build up around the openings
Roof vents - is the mesh still good? Small creatures also like to be warm
There may be more than I'm unaware of or didn't think of -