A ventilated vehicle seat includes a bag formed from impermeable materials enclosing a spacer material. The latter preferably includes upper and lower netting sheets and fibers extending between the netting sheets, the fibers being sufficiently resilient to prevent total collapse of the spacer material when the seat is occupied. An air mover forces air into or draws air from the bag is coupled to the air space between the air impermeable layers. Holes are provided in the top of the bag, and the sizes are preferably selected to equalize air flow over the seating surface, rather than having all the air flow through the openings nearest the fan. An optional, porous heating layer may be located above the bag. The ventilation and trim components are preferably sewn into the seat in a single operation.