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Join Date: Mar 2006
Posts: 1,325
Country: United States
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Texas has more cooling days
Texas has more cooling days per year, then heating days, correct? warm sunny dry summers, cool rainy, overcast winters?
I'm used to building energy efficent houses in Wisconsin, not in Texas, but I'll do my best to give some good advice, as building houses like this is what I have been doing for the last 4 years, and have been around renewable energy all my life, with our current house's electric bill being around $15 a month, for 5 people.
Windows: Low-E glass lets slightly less light thru it (a widely overlooked side point), their main advantage is that they reflects radiant heat, thus keeping your heat from radiating out thru the glass to the great unheated outdoors, if you want your windows to help heat your house put them on the south side where they will get the most sun, if you want your house to loose heat thru windows, put them on the north side, in otherwords, if you life in a place where you need to heat your house, large windows on the north side are an extreamly bad idea, the largest window you should have on a north side might be a small bathroom window, but if you live in some place like arizona, or maybe parts of texas, you don't want alot of windows on the south because of how much they will heat your house in the summer. but to conterdict my self you might want to go with south windows, and skip the east and west windows, if you get alot of hot morning, and evening sun in the summer that would be coming dirrectly in from the east and west, if that is the case, south and north windows, with a good roof overhang (in the summer the sun is overhead at noon, and lower in the sky in the winter) a good roof overhang shads the south windows in the summer, and alows full sun to enter the house in the winter (we do 3 foot overhangs, and no, they don't look funny), basicly, if you plan your windows correctly, and think about your roof overhangs, and live in a mild climet you can get away with minumal heating and cooling, saving you a ton of money, an example of this is a house I built 3 years ago that I visited this summer after it had been 100 degrees for a few weeks in the summer, and inside the house it felt almost cold, 72 degrees, and they didn't even own an airconditioner, good atic venting, good roof overhangs, and insulation.
Roofing: As I already said, let your roof overhang enough to shad the windows, there should be charts on the internet that tell you, based on where you live how much overhang you need for a window of a hight to get enough shade, while alowing full sun in the winter.
what you make your roof out of also makes a differnce, black shingles should not even be made, while, or grey reflect alot of heat, and if you get snow they are less likely to melt the snow, and snow can act as free insulation, some people don't like steel roofs, but if you are willing to go for steel it can be a great choice, it will last 50+ years, (compared to traditional asfalt shingles at 10-15 years, 35 years of you get the best) of course some people don't like how they look, and if you don't insulate your attic (insulate your attic!) you can hear the rain, and it sounds like you are in a shed or barn, oh, and after your steel roof has come to the end of it's useful life you can recycle it, asfalt shingles are considerd toxic waste, like car tires, and if you want to collect rain water off your roof, steel or clay is really the best option, unless you like the taste of tar.
Insulation: 2x4 walls are just silly unless you want to partition off a room inside, however 2x4's are cheap, and if you want to better insulate your house doing what is called a strap wall works extreamly well, as wood conducts heat, having a solid piece of wood (stud) go from the inside of your house to the outside, every 16 inches is alot of wood conducting heat, a strap wall is a 2x4 wall, with 2x2 straping nailed horizontaly, making your wall thicker, and leaving only small areas to conduct heat directly(thermo brake), this is a widly accepted building practice, and altho it does take a little more work (attaching the straping) it doesn't cost alot more then a 2x6 wall, and you get a higher insualtion value without making the wall thicker, and quiter, you can also do dubble straping, by putting 2x2's on both the inside, and outside of the 2x4's.
I would never build a house that has less then an R40 insulation in the attic, as that is where you loose most of your heat, and gain aot in the summer, all the houses I have built have had R65-R70 in the attic (around 20 inches of celulose/ground news paper), of course we also do about R45 walls, but this is Wisconsin.
Skylights: they are cool, pretty, cost alot, and are knowen for leaking, I am personaly a fan of light tubes, 12" tubes that have a clear dome on your roof, and a reflective duct to carry the light, I know they sound kind of hoky, but I've installed them in a number of houses, and seen them in in a number of others, and they are extreamly bright, and make a smaller hole in your roof, so less heat loss, and less area to calk/risk leaking.
You can take any point of energy savings to the extream, but most people don't even have it cross their minds while building.
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