Insulation, Radiant and Vapor Barriers - Should the north wall be thicker than the others?

Let's see if I can word this so it makes sense.....no laughing please!!

My "house to be" is oriented north to south. So in winter, one end takes the full north wind and in summer, the west side gets full sun (I live in Texas near Houston). The question is whether it makes any sense to make these two walls thicker (ie-more insullation) than the east and south. The insulation of choice will be fiberglass batting covered with a rigid foam foil-faced sheathing and tin outer shell.

Just for the purposes of this question, if you ignore air infiltration, will temperature be any lower on the north than the south? Obviously it feels colder, but this is largely due to evaporation of the skin......so does it hold true for a house?

I'm not an engineer but I do understand basic thermal dynamics. Always remember that warm air molecules move towards the cold. In the summer months you have the heat from the sun constantly penetrating into areas that are colder. It does not occur the other way around. In the winter months you will find that the heat you create within the house is constantly flowing towards the colder surfaces that lead to the outside which include your outer walls, windows,doors, and ceilings. There are other areas as well but these are the more common areas when at this time of the year heat containment is desired. Since heat rises you would expect a higher percentage of your heat loss to be through the roof.

In terms of choosing the right insulation keep in mind that there are three ways that heat will transfer (conduction,convection and radiation). The most commonly used insulations such as fiberglass and foams are designed to slow heat from "conducting" through the surfaces that lead to the outside. Neither of these methods really stops heat from transferring through rather it merely slows this process down. The thicker the insulation, the longer it takes for the heat to escape.

So in a nut shell yes, thicker walls will make a difference however that is not necessarily the only solution nor the most effective one. Keep in mind there are other solutions that don't require thickness. Remember when those shiny foil "space blankets" first came out in the early 80s and how amazed we were to find how well they helped "contain" heat? Since then we have seen other forms of thin insulating clothing which helps to contain your body heat in the winter. Both of these technologies has helped shape the way we think about insulation but, we are still stuck on the notion that 'thicker is better". I have a pair of Wranglers with a "thinsulate' liner. I have a hard time wearing these inside the house as they work so well in containing heat but boy are they ever nice when I'm outside at freezing and below.

Here's an example of an alternative insulation. We insulate ice arenas with a multi-ceramic insulation coating. The first two we did, one in BC and one in Quebec. These are steel buildings and as you can imagine they can get pretty hot in the summer months in fact most arenas cannot afford to keep open because the the cost of utilities to "keep the heat out". Remember heat moves towards the cold. We put the coating on the "outside" walls. They did not have the budget to do the roof even though we strongly recommended they do so. The facility in BC reported a 30% reduction in utilities. The one in Quebec averaged $80,000 per year in utilities. The building inspector refused to believe this coating was doing anything and after two years forced the contractor to apply foam to the inside walls. A year later the utilities were still $80,000. The contractor was upset because they were forced to waste $30,000 to apply the foam insulation. The coating which is as thin as a business card was doing all the work. On the positive side, it started to pay for itself as soon as it was applied.

When designing your insulation system cheaper and thicker is not necessarily always better.