08-10-10, 11:35 AM | #101 |
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Good stuff. The windows all look very good. Protecto Wrap is a pretty funny name.
After baking in the sun installing it, Protecto Wrap gets hilarious! In my best cartoon superhero announcer voice: "Protecto Wrap, Master of the Universe!" Is that the south face with all the windows? Yes, I was told for passive solar to put 7 - 9% as much window area as floor space. I used 9% as my figure to shoot for and ignored the reality math shows. In other words: I took 75 sf of windows (3'x5' x5 = 75) and divided by 864 sf of floor space. The windows are not 36" x 60" of glazing, due to the frames, etc and the floor space isn't 24'x36'. It is 24'x36' to the outside of the blocks, not the inside. I didn't bother to correct the figures as I said, "close enough. This is north Alabama, not Montana." All of the south facing windows are plain double pane windows. North, east and west are double pane, Low-E coated. The big overhangs should take care of most of the sun hitting the south facing windows. A bit later, it will get 6" rain gutters and a copycat rain catchment system, like one of the several I've seen here. |
08-10-10, 12:14 PM | #102 |
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It'd be nice if there was an easy calculation to optimize windows on the south face, but there are many variables.
It is a trade-off between introducing additional heat load in the summer to be removed, and introducing additional heat load in the winter to reduce heating requirements. Of course you want the incoming sunlight to reach an internal thermal mass so the heat can be utilized throughout the daily solar cycle, but without that mass there is still free heat during daylight hours. The presence of mass would permit you to increase the solar exposure, as you can store the peak heat during the day. The size and orientation of overhangs also affect the magnitudes of the additional load in summer and winter. However, solar angle maxima and minima don't precisely correspond with heating/cooling load maxima and minima, so this effect isn't a simple calculation. Excessive direct solar exposure can be discomforting, as it will cook you, essentially. I suppose ideally the light is directed onto a thermal mass and that mass heats the space & occupants indirectly. This leads to concepts like the trombe wall. Although it's nice to have the view afforded by the windows, and a giant wall in front of the windows doesn't help that! I suppose I'm preaching to the choir here lol. Anyway, I found a free program RESFEN good for selecting window areas and LowE coatings for a given building and its climate. I can't testify to its accuracy, but its by far the best free option available I've found. |
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08-11-10, 09:23 AM | #103 |
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mrd, thanks for the depth of info in that last post. I hope others take the time to try that free program out. As I have finished installing my windows, I'm "a day late and a dollar short."
Also agree with the trade-offs you've mentioned. I've mentioned previously that the building is not perfectly oriented to true south. It is either 7 or 13 degrees off. Since I couldn't figure out the direction of the 3 degree magnetic declination, I chose 10 degrees from magnetic and pressed on. In the planning stage, I was told up to 15 degrees from true south was acceptable by someone I trust. Plus, 10 degrees also sets it to about as much of an offset to the street as I could stand {yet another compromise }. Before virtually all homes {at least in the southeast} were equipped with air conditioning, awnings were quite popular. While I am not going to use a factory awning, if heat gain in the summer feels excessive, I can always craft something that could be mounted to the bottom of the overhang to shade the windows and pivot in and out as needed. The upper floor will eventually be air conditioned for the wifes use, but the lower level will likely just get a large {ceiling?} fan. |
08-13-10, 05:58 PM | #104 | |
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Keep the reports coming, I am starting to have some serious garage envy. Tim
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08-16-10, 08:21 AM | #105 |
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Tim, thanks for the interest and kind words on my barn project. It is becoming larger than life!
Nothing photo-worthy at all happened this weekend. I just worked on getting tar paper up on the garage door end of the building and trying to outsmart the two walk-in doors. I need to fix the concrete part of the threshold to accept the door. As it stands now, the metal threshold that a prehung door comes with sticks out about 1 1/4" past the concrete. That's sure to be a problem soon if I don't address it now. You wouldn't believe the amount of time I've spent trying to find and buy a paint color I like for the building. Since we designed it to look like an old barn that went through a restoration {renovation?}, I wanted to paint it a somewhat traditional barn red. After way too much time wasted on buying quarts of paint to try colors, I finally have ten gallons of paint to get me started. Ricky volunteered to help paint. We're painting the Hardieplank before we hang it. I may have to hire someone to hang the siding when we get it painted. I can't hang it by myself and Ricky can't help on a ladder. Will has become tied up in other matters and that makes it tough. Of course, all the help they've all given has been very greatly appreciated. I owe them all a serious debt of gratitude. |
08-16-10, 08:34 AM | #106 |
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I know I'm jumping ahead here, but what are you planning on doing on the inside as far as finished walls (if there are to be finished walls)?
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08-16-10, 12:07 PM | #107 |
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It'll likely be next year when the walls get finished, but they will get finished. My wife's already picking out the colors for upstairs.
After we wire it and save enough money to continue, we'll have the sprayed foam insulation put in the walls downstairs and sheetrock those walls. I'll probably use recycled loose fill insulation {like the stuff that gets blown in with the machines you can borrow from the Big Box home improvement stores} for the ceiling/floor area between upstairs and downstairs. I am still working out how to insulate the upstairs walls. Whatever we come up with, it has to be pretty well insulated, as we're going to heat and cool it by solar power. The barn will be off grid if AEC doesn't allow me to grid-tie my solar array. I'd run it guerrilla style for a while, but my wife was displeased with my cheating and I had to turn it off. We're still at odds with them, and I'll continue going to the meetings and trying to convince them to join the 21st century. |
08-16-10, 05:21 PM | #108 | ||
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Cellulose Insulated Attic Makes For a Cozy Home | EcoNewMexico.com Quote:
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08-17-10, 03:57 AM | #109 | |
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Quote:
Also you mentioned having it well insulated to allow solar heating/cooling. Reducing air leaks goes a long way in reducing the heating/cooling loads. Sprayfoam insulation also seals cracks, so that will make your walls airtight. If you're blowing in cellulose in the attic, you'll want to detail all the cracks and joints for making them airtight. An easy method is to spot spray critical areas with spray foam. Cracks at high and low areas are more of a problem, as stack effect pressure increases air leakage through these points. Also, if you use any fans for HVAC/ventilation, it's best to balance them so there isn't any net negative/positive pressure on the envelope. I suspect the large garage door will be tough to make air-tight. At the start of the thread you wrote there's 2" XPS between the slab and block wall, I assume that's at the slab edge, so you can see the top of that insulation when you're looking down along the floor perimeter? How is the short block wall itself going to be insulated? |
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08-17-10, 07:37 AM | #110 |
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Tim,
Thanks for the good advise. I wish I'd known that before I added 40 bales of Lowes blown in stuff in 2008. I won't use it in the barn if I can remember long enough. {This is me making myself a note for future reference} I read your write-up on the EcoNewMexico site. Then I noticed that today it is 94% relative humidity there. Wow, that sounds like the Southeastern US. I didn't think the Southwestern US had that kind of relative humidity. mrd, I went to their site, thanks for the link, and will be ordering a pair of solosiders today. They meet all of my wish list. American made and simple to use. This looks like it will help me save from having to hire help to side the barn. |
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