Yellowjacket wasps are certainly troublesome when they colonize and construct their nests inside of man-made structures such as your home's wall void.  Fortunately, yellowjacket wasp nests are typically single-season use constructions.  Unlike honeybees, yellowjackets do not store food in their nests that would allow them to survive from one year to the next.  The typically biology of the yellowjacket as described in the OSU Extension FactSheet: http://ohioline.osu.edu/hyg-fact/2000/pdf/2075.pdf is of an annual colony.  Only fertilized queens survive to overwinter.  In the fall of the year, new queens and males are produced by a colony.  The males mate these new queens, then the males die.  The newly mated queens go off on their own to find a place to overwinter. The following spring, these queens search for new sites to establish new colonies. 

The colony that produced the queens will slowly die-off including all of the workers, the old queen and all the males.  The old colony members will either stave to death or get frozen out by winter temperatures.

I suspect that the yellowjackets that are entering your home are following heat from the interior of your home that is leaking into the wall void where the colony is located.  One step that you may want to take is to discover where the insects are entering your room(s).  If you can find that entry point, your could introduce an insecticide through the hole to discourage other wasps from coming through the hole(s).  A ready-to-use powder formulation of an insecticide may be more effective than an aerosol type of insecticide.  A squeeze bottle with a nozzle tip would be useful for this purpose.  After the insecticide is introduced through the opening, seal the inside opening with caulk or spackling compound.  One thing we never want to do however is to seal exterior opening before the colony has been killed.  They will make new exits and they can easily chew through drywall. 

With cold weather approaching and lack of available food for the colony, I don't think that it is going to survive much longer.

An active colony makes a lot of noise.  One might be able to locate the colony by listening on the exterior walls of the room (the glass to the ear trick).  You can listen to see if their activity is lessening over the next week or so.  Also listen to see if you can hear them chewing at the drywall.  If it seems like they might be chewing at the drywall, then you might need to go the extra step to get them killed faster.