i would agree that a good heatsink can not need a fan, but a heatsink benefits a great deal from having a fan pull the heat away from it more quickly. if you had fins on a heatsink that were really long then you wouldnt need a fan as much. it obivously depends on how hot something is going to get whether you need both or just a heat sink.
i was a little hasty to post my idea about cooling, rereading that he is building his house i would totally agree that exhaust fans would be best and not that difficult as its new.
the power supply with fans idea (from computer) works very nicely though, but it is more for standalone closed racks where you could mount the ps to the back (where its heat doesnt matter) and cut out holes so that the fans can suck out the heat.