We are dealing now with possibly the most critical - and least understood - set of criteria in this entire exercise. We have seen earlier, that the Vastu Purusha Mandala determines the location of a particular room type depending on the resident deity of that space. Agni for example, being in the south-east and denoting fire, is the logic for putting the kitchen there - if possible. If not, then the kitchen goes to the north-west, or north, or east. Similarly, the toilets can be anywhere except in the south-west or north-east sectors. 

Both, the kitchen and the toilets, are sources of their respective odours. If such rooms are to lie upwind of the rest of the home, the environment within could get unpleasant in the extreme. Placing these rooms on the northern or eastern facades allows the smell to be released directly into open space. The north-east corner, though, is strictly taboo for such activities, probably because that would be a complete waste of the best part of the house.

For the record, the cow-shed (if you choose to have one) must always be in the north-west.

For living areas, the north and east are preferred simply from the point of view of coolness and comfort, while bedrooms, being the only areas which are used more at night than during the hot daytime, are recommended in the south and west.
Apart from this, children are advised to sleep with their heads to the east and adults with their heads toward the south. The west is "allowed" but the north is a strict no-no. This has something to do with the earth's magnetic field. There is no way that I can either refute or support this theory. However, I slept with my head to head to the south as a child and now have it to the east - with no adverse effect to the best of my knowledge.