Volvo Repair: 1996 Volvo 850 Brakes Fade, volvo 850, system mechanic

Question
Our daughter drives our 1996 Volvo 850 four door.  She complains that the brakes are "spongy" and seem to fade, especially during emergency stop.  Has this been a problem with the 850 model and/or can you direct me to a solution.  We have had 850 since new, and seems to have been a problem in later years.  Is there a valve at fault?  

Answer
what brake pads are you using volvo original ? it is hard to say  what it's if i dont drive the car  . but here are some things that maybe are  bad first it can be you  brake pads and brake disc  if they are aftermarket not orginal volvo  or you have air in  brake  system  mechanic can tell that  if he knows  and last you have bad  bad calipers or master cylinder  we dont have to many problmes  with brakes on volvo so long you use and replace parts with original volvo parts  if you from chicago i can help you .good luck