Based on your screen name, I assume you're building in Texas. Unless you're way up in the panhandle somewhere - unlikely since you mention you have a lake place and there aren't many lakes up there (LOL!) - you're in an area where the number of degree-cooling-days per year is 2 to 2.5 times the number of degree-heating-days. Or, to put it more simply, you normally need to run you air conditioner 2 to 2.5 times as much as you do your heater! Be aware that much of what you will read regarding passive solar was written with cooler climates in mind.

For those of us in hot dry or hot-humid climates, passive-solar must be far more about keeping excess heat OUT of the house (or moving it to unoccupied areas) than it is about using the sun's heat to warm our homes on a few cold days in the winter.

So the very first rule is, you want to select windows with low solar-gain and low emissivity numbers. In colder climates they need high-solar gain glass. The low solar gain windows are sometimes called "Low E 2" windows so be sure you get the right kind.

I love bright light-filled rooms and wanted every major room in our house to get light from two or three directions but I also didn't want to pay thru the nose to keep temperatures comfortable. So I did a lot of research on passive solar principles when designing my home.

As a central Texan, I basically decided that, given that we can and do often have temperatures rising into the 80s in December and January and only very seldom have temperatures that drop much below freezing, it would be better for me to avoid daytime solar gain as much as possible pretty much YEAR ROUND. While we might have 20 or 30 days each winter when I'd want to have the sun help heat my house, we're just as likely to have 20 or 30 days each winter when excess heat from the windows could easily force me to have to turn on the AC.

This meant putting most of my large windows on north facing walls. These windows provide plenty of natural light without direct solar heat gain.

On east facing walls, you can have large windows if you have overhangs deep enough to begin shading them completely by around 9AM. Downstairs I have a wrap-around porch and trees that shade my large east-facing windows. I do have large unshaded east-facing windows upstairs in my master-bedroom and in one of the secondary bedrooms. In the summer I keep these windows covered with insulated window coverings that are opened for only a little while each morning as we get dressed. In the wintertime, I usually leave the drapes open to allow the sun to warm those rooms a bit because I know that even on the warmest winter days, by the time any heat really builds up, the sun will no longer be hitting those windows.

On south facing walls, you should generally limit the number and size of windows and have deep overhangs that will shade them completely in the summer. Small windows set high on the walls with overhangs deep enough to keep them fully shaded in the summer but shallow enough to allow some direct sunlight to enter in the winter are best. But note that in hot climates - even in the wintertime, you DO NOT WANT direct sunlight entering a bunch of large windows. If you have too much unshaded south-facing glazing, your home will get too hot on those balmy winter days we enjoy. If you decide you must have large south-facing windows to take advantage of views, then put a deep covered porch on the south side as well so that, even in the winter, direct sunlight is blocked from all but a very small portion of your south-facing windows. I do have a bank of large south-facing windows in the breakfast nook of my home but they are almost 100% shaded year-round by a second floor deck and by a grove of nearby live-oaks which are green year-round. On the second floor, the only south-facing windows I have are in bathrooms and, in addition to double-paned, low E, low solar gain windows, they have glue-chip glass which cuts down on the solar gain even more. Total unshaded south-facing glazing in the winter is probably less than 3% of my square footage. And total unshaded south-facing glazing in the summer is as close to zero as I can make it.

As for west-facing windows, in addition to large overhangs, I very deliberately positioned our two-story semi-detached garage on the west side of the house so that it almost totally shades the entire western facade from the setting sun. The three upstairs west-facing windows get direct sunlight for about an hour a day. The one west-facing window downstairs gets no direct sunlight at all. All four windows however receive reflected sunlight from the side of the garage for a good portion of every day so those rooms are all still nice and bright. (Reflected sunlight carries a lot less heat than direct sunlight.)

BTW - even though both the walls and the roof are insulated, our garage stays toasty warm year round and in the summer can get downright hot...evidence of the heating due to west facing facade. The upper room over the garage was originally intended to be storage so we didn't bother to put in HVAC. It then turned into DH's man-cave but he uses it only when the guys come over watch football or play poker. On those occasions we use a couple of portable AC units to cool the place down. They're not terribly energy efficient but since used only occasionally, its better than paying to keep the whole space air-conditioned all the time.

In addition to optimally sizing and placing your windows, the more "thermal mass" your building materials have the better. Thermal mass absorbs excess energy when it is warm outside and releases it slowly when it is cooler. Whether in a hot or cold climate, thermal mass helps to "even out" temperatures.

Good insulation in the walls and attic is also important to keep excess solar heat from penetrating to the interior of your home. Also, keep in mind that light colored building materials reflect more sunlight and therefore don't absorb as much heat. So, light colored brick or siding will help keep your home more comfortable. Light colored roofing shingles or a highly reflective metal roof are also helpful. We painted our hardiboard siding a light cream color and, because the budget wouldn't stretch to metal roofing, chose the lighted roofing shingles we could find - Owens Corning Amber.

You also want to provide a way to move excess heat OUT of the spaces where you actually live. In warm climates, high ceilings provide a place for excess warm air to go. And, if you build a two-story house, the downstairs rooms will stay much cooler during the day as the warm air rises to the upper rooms. So, if your daytime living areas are downstairs and your bedrooms are upstairs, you'll be in the coolest part of the house when it is warmest outside and in the warmer part of the house at night when it is cooler outside. This should help reduce the amount of heating and cooling you need to do year round

Maximizing ventilation also helps to reduce your dependence on air conditioning. Operable windows on opposite walls allows for cross ventilation. This is especially good if you have windows that can be opened near the ceiling on the warm (south & west) sides of the house and opened near the floor on the cooler (north and east) sides of the house. Even on days when there is no breeze, rising warm air will escape from windows opened near the ceiling and will draw in cooler air on the other side of the house creating natural ventilation. Additionally, ceiling fans work wonders. They use very little energy but can easily make a room feel 5 degrees cooler. So, instead of needing to set the thermostat at 73 degrees, you can feel perfectly comfortable at 78 degrees. Just remember fans cool people, not rooms, so you should turn them off when you're not in the room.

Finally, design your HVAC system so that the units and all ductwork is INSIDE the heated/cooled envelope of your house. Do not let your builder put ductwork and your HVAC units into your attic. Consider that most codes in Texas call for at least R-30 attic insulation (the equivalent of 9 inches of the pink stuff) but flexible ductwork has only about 1.25 to 2.5 inches of insulation around the central core that carries cooled air into your home. (R 4.2 to about R 6), Even when the duct work is brand new, isn't "leaking" or crimped or otherwise improperly installed, consider how much harder your HVAC unit has to work to cool your home when it must first push the cold air it generates thru 10 or 20 or 50 feet of ductwork that has only R4.2 worth of insulation between it and attic temperatures that may reach 150 degrees in the summer! And, flexible ductwork almost always starts leaking after a season or two which means everytime you do run your air conditioner, you're paying to dump cool air into the attic. Far better to run smaller ducts with less insulation through open web trusses within the heated/cooled envelope of your house. And, if the ductwork starts leaking, well, the cooled (or heated) air is going INTO your home where you want it instead of into the attic.

Insist that your architect draw up the HVAC plan requiring the HVAC ductwork run inside the heated/cooled envelope of the house and incorporate that plan in your building contract. Otherwise your builder will probably insist that having the HVAC unit in the vented attic and having flexible ductwork running throughout the attic like a giant spiderweb is the "way we always do it" and therefore the only right way to do it. Do your reading and you'll learn that it is not the best alternative.

Hope some of this is helpful...