Most energy efficient building shell
Hello all
I am in the planning stages of building a new home
All the kids will be off to collage next year and I and my wife want to down size
The starter question is building shell, followed by doors and windows, roofing material leaning towards steel
Is there a true real winner in choosing the best building techniques?
To achieve the most energy efficient home, I want to max out energy efficient home
I would rather pay a little more upfront than paying out in the long term
The house will be in the <!—-><!—-><!—->Dallas <!—-> <!—->TX<!—-> <!—-> area so cooling and humidity control will be the
Number one concern then heating the other three months out of the year
Is there a best building material product for he weather me have, rare but deadly strait line winds and tornados.
I believe part of the insulation recommendation is political, so what values are best to use.
For the walls- Strength, total wall insulation values, air infiltration, thermal mass
SIP’s metal or osb skinned , ICF what style how thick of walls , Larsen truss walls , mortar less concrete block poured solid with a exterior of 4†EPS
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For the roofing structure, trusses with blown in cellulous insulation, how much- R40 or more? SIPs metal or osb skinned how thick
Any feedback is welcome
Thanks
Ken
Replies
Ken -
You will get lots of opinions/politics/etc here. I was in your spot 2 years ago.
I think it comes down to 3 things: the law of diminishing returns, personal preference, and what/who is available in your area
I am in an ICF house now (Amvic 6" walls, 5" of foam), it is below freezing outside, was yesterday, and we have yet to turn on the heat. (its quite warm in here) The ceiling has R50 blown fiberglass on top. If I had the $$ I'd have sealed the ceiling with Icynene, or used sips panels over a timber framed roof. I spent a lot of $$ on good windows too.
VaTom frequents these boards, his house is a PAHS design, concrete with foam on the outside - cheaper than mine to build, and he seems to enjoy great energy savings.
I am a fan of the solidness of concrete housing - for noise, comfort & energy reasons, but also strength - it is comforting to watch the wind whip outside and be well sheltered - quality of life issues.
Each method you mentioned could be considered "the ultimate" they each have tradeoffs, especially in regards to the trades, but each could yield a great house.
Good luck with your project.
VaTom frequents these boards, his house is a PAHS design, concrete with foam on the outside - cheaper than mine to build, and he seems to enjoy great energy savings.
Yup. Mine's simple commercial construction, the key to our low-cost shell. Even our substantial steel roof, supporting a couple hundred tons of dirt is very inexpensive. As to effeciency, we need neither a heating nor cooling system with 4166 heating degree-days and 1131 cooling degree-days.
But the OP isn't particularly interested in going underground. PAHS makes good sense in every climate I've looked into. Inexpensive to build, nothing to maintain. Ours is hardly cave-like. And the last hurricane remnant that came through dropped the top 50' of a tree on the roof. We didn't know about it until I went out the next morning. No damage.
Dehumidification is generally accomplished by dehumidifier or ac. I've built 2 PAHS houses here in central Va, definitely an ac climate. One uses ac (for dehumidification), the other dehumidifier. We keep our houses the same temp summers and have similar elec bills, never see $100 for total elec houses and well pumps. 20k and 26k cu ft.
I do a little better (with my dehumidifier) as we also utilize a heat pump water heater that has a byproduct of cool dry air (sound like ac?). It provides 50% of our dehumidification needs. Anybody with dehumidification and/or cooling needs should design their house to take advantage of one IMO.
Ventilation is not a small issue with tight houses. We do a total air change every 2 hrs (.5 ACH), and positively pressurize the house so all leaks go out. With that much ventilation we have fantastic air quality, but also bring in a lot of summer humidity. It's a trade-off. My PAHS client chooses not to do the air changes, claims it's unnecessary. I think he's wrong, but they're very happy. They also didn't bother to hook up the heat pump water heater, gave it away.
Both these houses are so low-cost to live in that we can be pretty sloppy about trying to get more efficiency. Neither we, not the client, bother with window coverings even though I did heat loss/gain calcs and know the benefits we could get. Our 2.5" of xps on our exposed walls turned out to be slightly over-insulating, compared to our low e windows. So for the client house we only used 2". As I mentioned, preformance is fine.
Little to dislike, I've got another one (very similar) started for us. BTW, the client house appraised 50% higher than construction cost for his mortgage. Certainly not entirely due to the shell, but it was a large factor. PAHS Designer/Builder- Bury it!
Tom, I am very interested in building earth sheltered someday down the road. Any links you can offer to help with my education on that?-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
An excerpt from the PAHS book that I didn't exactly follow: http://www.axwoodfarm.com/PAHS/UmbrellaHouse.html Far as I know, it's the only book on the subject.
Here's a page put up by a guy promoting discussion of passive heating/cooling, about our digs from emails and pix I sent him: http://paccs.fugadeideas.org/tom/index.shtml I get a steady trickle of interested folks. Talking with 2 couples currently. Unlikely I'll actually build anything for either one, but we'll see. Mostly I'm just happy to promote the concept. Definitely not interested in building many houses.
PAHS can look like about anything. I ignored Hait's buried dome and built something I could get engineering for, and build, easily. I find thin shell concrete fascinating but not air-forming, more on the lines of what Felix Candela was doing above grade. http://www.anc-d.fukui-u.ac.jp/~ishikawa/Aloss/page/Candela_Work.htm Burying a shell eliminates all the common problems those early guys had.
A GC here wants PAHS in early F. Gehry style (Santa Monica) with all that galvanized corrugated steel panel. No problem. Could probably make a Victorian fascimile, but that'd be more difficult.
It's the heating/cooling system, not the architecture.PAHS Designer/Builder- Bury it!
Tom on the PAHS Design homes
In general terms if I were to do the day method
What would the approximant price per square foot?
On your web site it mentions you are building another home
What have you chosen to do different?
I think you mentioned that you have a 13 degree swing through out the year
What is the base line temp for dead of winter and peak summer time?
Do you have a graph of the Temperature Swing through out the year?
What type of auxiliary heating do you use?
Here in TX it might be 40-50 one day the 60 to 80 the next
How responsive is your home or is it just rock steady
Is passive solar heating a large part of your strategy?
Light coming in through your windows to heat your floor area
I think in my area I would need over hangs to shade and keep the house from over heating
Do you think the in ground heat pipes are worth considering and are cost effective
As you mentioned I believe you would have to use up lighting combined with an electrostatic air filter
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On the umbrella roof structure with our heavy clay soils, they wick water along way
In some of the farmer barns in the area even though they have a concrete footing to support their barn moisture will migrate under the footing and into the inside of the barn mating it muddy, I am not talking about standing water. In our back yard in the lawn area there are crawdad holes scattered around there is no standing water any where in the neighborhood
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Do you think there will be a resale issues with you current home
Thanks
Ken<!----><!---->
What would the approximant price per square foot?
On your web site it mentions you are building another home
What have you chosen to do different?
$22-23/sq ft shell, depending of form labor and required rebar. Get a subdivision form guy in there and cost should go down. A lot of the low cost is the barjoist roof.
The next house gets another foot of dirt on the roof under the umbrella, a guest suite, indoor 2 lane lap pool, large garage, and a utility room. With the pool needing heat, we'll have substantial (recycled) active solar with wood-fired boiler backup. Architecture is very similar. As we're installing active solar I've accumulated old cast iron radiators so we'll also have thermostat backup space heating. It faces W. rather than S., but that shouldn't make much difference to the PAHS. Again, large trees for summer W. shading.
I think you mentioned that you have a 13 degree swing through out the year
What is the base line temp for dead of winter and peak summer time?
Do you have a graph of the Temperature Swing through out the year?
What type of auxiliary heating do you use?
Without us doing anything, we go from 65º in February to 78º in August. Diurnal temp swings rarely exceed 3º. Base line? The mass gradually cools off and then gradually heats up. It's a 6 mo process. Hait buried temp sensors in his earth mass and found it incredibly boring to watch maybe 1º/month change. It takes about 3 yrs for the mass to stabilize. Then you get equilibrium.
65º is a little chilly for us to sit around evenings. There's a small woodstove here that warms up our 20k cu ft nicely in an hour. No reason to run it damped down, so very clean burning. A little like a masonry stove, but the house is the mass. Also have the opportunity to get close, coming in from sub-freezing temps and bake one side, then the other. We get great convection currents with this roof. Bear in mind that 65º is also the target temp for degree-days, we just prefer a little warmer. If your outside temps were in that 13º range, you'd need very little heating or cooling, right? And we wouldn't be having this conversation. <G>
No graph. Hait might have, don't remember. It's all so gradual we really don't notice. Rock steady is a good description. Too much mass to change rapidly. And makes overheating very difficult. Summer western sun might do it, but the client house has 1500 sq ft of unshaded SW windows. I told him it was a mistake, but it turned out to be much less than I expected. Doesn't overheat. We have mature trees shading our western glass.
These are not low energy houses. We go through huge quantities, just take advantage of surplus, storing, and enjoying later. Annual.
We get some winter solar gain through the glass. Calculated it once but don't have the numbers at hand. As we don't use window coverings it isn't much per day. We are over-glazed (over 25% of floor sq ft) and suffer thermally from it, but it's not hard to live with and we like the light.
I forewent earth tubes, if that's what you're asking. It's one of the two passive dehumidifiers I know of, the other being air wells. My fear was fungal incubation (legionnaire's disease, etc.). I know of no one with a humid summer who's dared. An active addition to the air system should solve the danger with UV, but I don't really want to experiment on us. One of the major reasons we don't get Hait's performance, 7º annual swing.
Electrostatic air filter? We don't. A simple pleated filter catches well. We're moving a lot of air through here. Also makes our moderate radon risk moot.
Only moving ground water (under the umbrella) will affect PAHS performance. Water does a much better job of storing heat than dirt does.
Do you think there will be a resale issues with you current home
Good question. I think everybody should have an exit plan. We do. Seems prudent to make reasonable resale concessions. This place is more of a guest house on the property (expensive land), rental is now what we're planning. The client house got a mortgage appraisal which presumably addressed that issue. He has an air heat pump for that and got a great appraisal, which (correctly) ignored the heating/cooling benefit. Both look like houses, not caves. Our next place will have cental ac easily added- for resale. Thermostat comfort control is important. I wouldn't expect a buyer here to think ac an option, especially in an expensive house. Same for a heating system.
PAHS Designer/Builder- Bury it!
Tom, would you have any information on the cost/performance difference between the cast concrete/foam wall you are using vs ICF?
Looking at a house with a walk-out basement, Owner is asking about ICF for the 10' stem walls, the usual here is concrete, no foam._______________________________________________________________
tagline free since 2006
Tom, would you have any information on the cost/performance difference between the cast concrete/foam wall you are using vs ICF?
I haven't compared costs since ICFs were claiming R50. At that time, they were close, varying primarily on your labor cost. For PAHS buried walls, ICFs have the insulation in the totally wrong place, on the concrete. Needs to be in the insulation water-shedding umbrella.
ICFs I strongly suggest to anybody who won't form a traditional cast-in-place wall, particularly DIYers. For exposed walls, it's a close second in performance to what I do. Cloud once dug up gov't info (Oak Ridge) on foundation insulation placement. It confirmed what he and I already knew, insulation should be on the outside of the concrete, using the mass to moderate temp swings. That's how adobe works. PAHS does the same thing, just with immensely more mass (dirt) and it's insulated. There's a world of difference in performance between a buried house and PAHS.
Looking at a house with a walk-out basement, Owner is asking about ICF for the 10' stem walls, the usual here is concrete, no foam.
If the choice is uninsulated concrete or ICFs (apples and oranges), by all means spend the extra and go ICF. As I mentioned, won't favorably compare with adding an insulation umbrella, even around a conventional basement, but much better than nothing. This is a question about if you should insulate? You know better. Then it's a matter of what method will actually happen.
Or maybe I misunderstood. In which case, disregard the above.PAHS Designer/Builder- Bury it!
Thanks for the input. I have built ICF homes, even one for an (gulp) engineer. The performance is remarkable and I would recommend a properly designed ICF structure as one way to achieve adobe-like performance.
My understanding of wall performance is mostly limited to above ground, however, and I guess the question really was:What would be better on a conventional house with a walk out basement - ICF, or concrete with the foam outside, ala PAHS?
'Better' as it pertains to cost/benefit as opposed to concrete alone, which is what everyone else here does.
One advantage I can think of for ICF's in this case would be the ability to build the exposed portion of the walkout as an ICF wall._______________________________________________________________
my tagline has fallen, and can't get up
Before I built our ICF home, I was dreaming about filled block or solid concrete with foam outside, but wiring, attaching siding, and similar issues plagued my thinking.
Maybe a little research could have saved me, but ICFs were the easy way out.
Treat every person you meet like you will know them the rest of your life - you just might!
What would be better on a conventional house with a walk out basement - ICF, or concrete with the foam outside, ala PAHS?
'Better' as it pertains to cost/benefit as opposed to concrete alone, which is what everyone else here does.
One advantage I can think of for ICF's in this case would be the ability to build the exposed portion of the walkout as an ICF wall.
Gotcha. This isn't complicated.
ICFs and PAHS have similar insulation costs (ICFs in the purchase price). The reason PAHS works better is more mass. That's the annual (or upwards, depending on amount of mass) heat storage at work. ICFs don't have enough mass. Plus they have a layer of insulation on the inside of the mass, wrong place. Slows heat transfer in both directions. We're assuming you want/have comfortable mass temps.
Even with a walkout basement (which I've done) PAHS works better than simple insulated buried walls. Again, more insulated mass under the umbrella.
For the exposed wall, there's not going to be a lot of difference between ICFs and a simple concrete wall with insulation on the outside. Until you look at the specs. ICFs are usually thinner concrete, less mass. ICFS often have less insulation on the outside of the mass than my 2" XPS. But to the resident, I wouldn't expect noticeable difference. On the exposed wall. To get a true picture you'd have to do a complete heat loss calculation which would include climate and mass. I wouldn't bother. If somebody wanted ICFS, I'd say fine- for the exposed wall.
That walkout basement where I did a PAHS insulation umbrella noticeably outperformed a neighbor's basement that wasn't ICFs but did have the same insulation on the outside of the walls. The difference was amount of mass. Properly placed, more is better.
That's why our place doesn't need a heating system. If we'd settle for that degree-day 65º target, we'd use zero supplemental heat. And our place isn't very successful compared to Hait's 7º annual swing. I cheated a bunch on his recommendations, for esthetic, economic, and health reasons. Still worked pretty well.
ICFs are good, just not as good. Summer cooling, ICFs are much worse unless you have large diurnal extremes, when you'd want even less, or (ideally) moveable, insulation. You've read Steve Baer's work? Very impressive, but I'm very KISS. PAHS Designer/Builder- Bury it!
Thanks, Tom.
Intuitively I knew what you were going to say in general. My understanding of these designs lacks considerably compared to yours. I am not knowingly familiar with Baer's work by name, although I have read extensively for many years, possibly I had come across him at some point.
My first resource for these types of structures was "Earth Sheltered Building Design' - or something close to that title, circa about late '70s. I just looked for it in my library, it must be still in a box or perhaps it didn't make the trip to Colorado.
Of course, these earlier designs did not consider the excellent foam insulations that are available now.
The problem that I have had with these designs and also with passive solar design, is the fact that I have primarily lived and built in the American Southwest. The most important design consideration is usually how to limit solar gain and calculating storage mass to handle the abundant sunshine.
My main concern about the house in question here is in providing a better product to my client. It would be easy to be more efficient than standard practice here, but the cost to do so should always be weighed against the benefit.
What I failed to explain about the 'normal' practice here is that along with bare concrete stem walls, the walk-out walls are usually framed wood walls - not terribly efficient, to my way of thinking, but then folks here are still using R-13 exterior wall assemblies.
I try to build the most comfortable house that my client can afford, whatever the design or method.
Thanks again for your time.
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my tagline has fallen and can't get up
You're welcome. Always nice chattin' with ya.
Steve's playhouse was called Zomeworks, Albuquerque or thereabouts, started up maybe late 60's. Lots of ideas tested. I used to fantasize about working with him. Never did anything about it. Was kinda busy avoiding that "Greetings" letter from the army.
Hait, with PAHS, went way beyond "earth sheltered housing design" (from U. of Minnesota), a very important book, by answering a number of questions they posed. Like, where should you insulate? His testing determined rate of heat travel through dry soil, culminating in his recommendation for insulation umbrella size.
I took his word for it and put in my money. Figured it couldn't be all that bad and didn't have much, if any, financial penalty. Even though I substantially cheated on the design, it worked/works surprisingly well. So I proselytize.
Unfortunately, almost everybody assumes that you have to build his (or my)architecture to get the performance. Whereas, the architecture has nothing to do with it. DW wanted lots of glass. We've got it and pay the temp penalty. Next house we'll do the same.
PAHS doesn't have to be a heating system. Awhile back somebody in Texas was asking if it'd work with their zero heating degree-day climate. No problem, just need to design the mass to cool off as much as possible during their very brief winter so they could dump excess house heat the other 10 months. How well could it work? I don't know, not knowing how to model it. A Denver engineer once offered me that service but I haven't bought one. Heat gain/loss calcs would give me an idea. More importantly, just like our place, even if it wasn't totally successful it'd be better than anything else going.
There's a guy in Washington who's designed a lot of alternative houses and vehemently disagrees, but won't give numbers. Doesn't even acknowledge climatic differences. I'd like to test a couple of his places.
Barely knowing enough with a computer to get something posted here, I rely on a vintage dog-eared copy of "Other Homes and Garbage" for my calcs. It's an engineering manual written for non-engineers. Tedious to crank out the numbers, but it serves.
Mass doesn't care if it's losing or gaining heat, just seeks equilibrium.
I also admire the work of a guy in New Hampshire (Vermont?) whose house weighs only as much as an SUV. Made of 1/4" plywood. With good insulation he's very comfortable. I don't want to live in it, but it works. PAHS Designer/Builder- Bury it!
VaTom,
I would be real interested to learn more about the type of construction your talking about. Any leads??
H
Follow the links. Happy to add whatever I can when you get back.PAHS Designer/Builder- Bury it!
Thanks for all the feedback
I have had a long time fascination with underground, earth bermed homes
If we chose to live in a rural area then I could actually see living in a PAHS home
If we / my wife choose to live in town, even that means living in a small community of less than pop 2000
The style of house we are looking at is a small farm style house, high roof / lofts
At least front and back porch. No west facing glazing.
I am planning a full basement even though they are not very common in TX
It sounds like from the comments that concert block faced with EPS on the outside is less expensive to build and more efficient than the ICF
One of the big problems in our area is the heavy clay soil, it moves a lot between dry and moist, a lot of people actually water there foundations in the summer with soaker hoses to try to keep the soils moisture level consistent
We have a community of the concrete dome homes locally
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Would the PAHS design have any problems with the heavy clay soils and the movement that comes with the soil?
What is the point of diminishing returns in the thickness of the EPS to the outsides of the block walls 4”, 6?”
At this time my roofing choice would have to be metal skinned Sip’s 6” or 8” thick
What are the advantages and disadvantages in comparing an AC and Dehumidifiers?
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I will have to do some research on heat pump water heaters
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The home we will build will defiantly built for the long haul
The 900 pound gorilla for us will be the rising energy prices, so I would like to get a handle on it in the design stages and building choices
Ken
Hi Ken,
You ask good questions. Just returned from across state, celebrating my mother's 95th birthday, it's late but I'll try for coherency.
You originally asked about the most efficient shell, which isn't addressed by PAHS at all. All my shell does is let the PAHS work. At the risk of elaborating the obvious, it's based on substantial insulated mass, Annual Heat Storage. Both a heating and cooling system with no moving parts, Passive.
Would the PAHS design have any problems with the heavy clay soils and the movement that comes with the soil?
The short answer is no. But what you're really asking is if the shell would have a problem. That, of course, depends on the shell. PAHS doesn't dictate a shell, other than something that permits heat flow. My shell is reinforced concrete.
Expansive soils require different treatment even with reinforced concrete. My experience is from Denver where bentonite will sometimes collapse basements. If they're constructed correctly, mostly limiting ground water entrance to nearby bentonite, no problem. The other choice was to allow a space for the bentonite to expand. But I'm not an engineer, and you should consult one.
What is the point of diminishing returns in the thickness of the EPS to the outsides of the block walls 4”, 6?”
At this time my roofing choice would have to be metal skinned Sip’s 6” or 8” thick
A heat loss/gain calculation will tell you when you get diminishing returns beyond what you think reasonable. This is subjective. For me, our low e windows accounted for about 75%, making increased insulation not worth my money. My client agreed. Not all would. I also mentioned that we couldn't be bothered with window coverings to better our performance.
What are the advantages and disadvantages in comparing an AC and Dehumidifiers?
Without PAHS, I can't imagine you'd be happy without ac, but I haven't taken the trouble to look into your heating/cooling degree-days. Both will dehumidify well. IIRC, Cloud once mentioned that his dehumidifier worked harder than his ac in his Monolithic dome in Asheville. My client here set his ac at what our house naturally does and got all the dehumidification he wanted, but without our air changes. Our next house will have a small ac available and I intend to test the difference. Not that it'll make a large electric bill difference. I already mentioned the heat pump water heater advantage, which made by far the largest difference. Blanket recommendation where the climate warrants.
Your concern with rising energy costs is only prudent. I talk with a number of folks who go way beyond that by assuming unavailability in the relatively near future. Don't have all the answers myself, but we're pretty well situated if the grid goes down for a week... or a lot longer. But neither dehumidifiers nor ac work then, unless you're generating your own.
Happy planning.
PAHS Designer/Builder- Bury it!
As for the most efficient shell question
Let me define the question better
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Lay out wise and size, the starting point was something similar to
The <!----><!---->Wind River<!----> design on the harmony exchange web site
28 x 28 foot print, 50% loft, fully finished basement for the master bedroom
Orientation wise, no west facing glazing for heat gain purposes
Small yes, but with the rising cost of energy, I do not want to be house poor and
Be locked into paying high $$ just to be comfortable
Size is small but comfort is a major issue
Tight home with minimized air infiltration, Air quality and exchange is a concern also
Heating is a minor concern; cooling and dehumidication are the major concerns
I am just trying to find that sweet spot, were everything works together
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As far a the shell construction choices
ICF / SIP’s roof
SIP’s
Poured solid concrete block with eps foam attached to the exteriors, SIP’s roof
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Quality windows and doors
I would like to include leading edge technology if the price and return are reasonable, Heat pump water heater, geo thermal heat pump, heat pipes. I want to get it right the first time around.
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The PAHS concept home is appealing to me, again heating is a minor concern; cooling and dehumidication are the major concerns 9 to 10 months out of the year
Today its 60 and drizzling tomorrow the forecast is 85 to 90
If I could do the PAHS home it could be bigger, it would just need a larger heat sink for cooling proposes
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I believe this is the cooling and heating data for my area
Computed Monthly Degree Day Totals<!----><!---->
412244 13960 <!----><!---->DALLAS<!----><!----> LOVE AP TX<!----><!---->
http://www.ncdc.noaa.gov/oa/climate/normals/normdegdmeth.pdf
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Thanks
Ken
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Your eyes are better than mine to see that tiny script. What I dug out for Dallas-Fort Worth was 2370 heating degree-days (base 65º0) and 2603 cooling degree-days (base 65º, which is pretty chilly for a cooling base). Means you actually had almost equal heating and cooling requirements over the last 30 yrs.
Think about it, doesn't get much easier for annual heat storage than that.
Gotta run but I'll get back later.PAHS Designer/Builder- Bury it!
So if the heating and cooling degree days are approximately equal
You just need a large enough of a heat sink / thermal mass
To exchange the heat and cooling load through out the year
How do you figure in the windows, air exchange, and ac and humidity control?
Ken
Ken, a little slow getting back, sorry.
If you do heat gain/loss calcs, you'll know what you need to store. Part of that is air changes and heat gain/loss from whatever you're using to dehumidify. Can get a little complicated. Hait's book explains rate of heat movement through dry soil.
All calcs depend on assumptions, like average climate, and if you're expecting to exactly determine performance, you'll be wrong. What you want is to get a feel for how something's going to perform, add a safety factor, and hope for the best. You won't be far off and the difference will, IMO, be negligible. Kinda like the difference between my dehumidifier and my client's ac. Both work so well I'm planning to test in our next house, but it's academic curiosity.
I'd do it here but reinforced cast-in-place doesn't lend itself to remodel.
PAHS Designer/Builder- Bury it!
Ken -
It is great to see folks really thinking about these issues - I am of a similar mind
If your house is 28x28 (very efficient use of space) and well insulated, a GSHP (geothermal) might be past the point of diminishing returns. It will take very little energy to heat or cool such a space, as in a water heater w/ a few pex tubes in the floor/walls for heat, and a built in window unit for cooling.
My ICF house is in the midatlantic climate (heating and cooling) 2 stories of 1712 s.f. each. A $300 sams club a/c unit cools the entire space handily. In my last house, my geothermal system was $8K and I did the install. It would take a lot of summers to make up the price difference.
You are wise in spending your $$ on the shell.
Treat every person you meet like you will know them the rest of your life - you just might!
I am planning a full basement even though they are not very common in TX
You will want to get ahold of a geological survey before you start hunting out lots in either rural or suburban Dallas County.
Because the County spans across the Trinity River estuary, there are varying depths of sedimentary rock strata (the lovely, black, "gumbo" montromorilite-laden clay soils rides over that). It's very possible to hit the Austin Chalk strata as shallow as 12-36" below grade. The Austin chalk then can be as shallow as 8-10' before hitting a blue shale strata with a hardness close to ledge. This can complicate basement construction no end.
Since your concept is for a steep-pitched, "farm style" roof, I'd use the Orlando Hot-humid concept from Building Science as a starting point. Dallas is enough drier on the prairie there to almost use the mixed-humid construction recommendations (the insulation model recommended certainly works).
Between the reseach & articles from Ray Moore & Joe Lstibuek, in Dallas County (and really most of Colin & Denton, even right out among the lakes), I'd likely spec a wood floor deck over a conditioned crawlspace (basement in your case) with a structural metal stud wall (or hybrid pipe-frame-galv. stud system) with the insulation mass & weather-tight plane outboard of the structural plane. The metal frame gets you a (tiny) bit more strength in line & downburst winds. Having the insulation & weather plane not in the structure helps improve the sealing of the envelope (and gets you some architectural 'depth' at the openings).
After that, it's more the choosing the external materials & features. Ditching (near pointless) attic venting lets you install a nice rustic galvalume roof, and carry that into sheilding porches for the Texas Farm look. I'd plumb for gas--either NG or on-site propane as much as possible, as gas prices (seem) a bit more stable than electrical prices across the state of late (unless one is in TXUs clutches, that is . . . <g>)Occupational hazard of my occupation not being around (sorry Bubba)
Yes that white rock is not too friendly<!----><!----><!---->
I live in <!----><!----><!---->Grayson<!----> <!---->County<!----><!---->, <!----><!---->Howe<!----> <!---->TX<!----><!---->, now maybe staying or going to <!---->Princeton<!----> area of <!----><!---->Collin<!----> <!---->County<!----><!----><!----><!---->
Were I live know we have plenty of depth coverage of that wonderful black gumbo soil<!----><!---->
But I have lived where that white rock was only covered by at the most 12”<!----><!---->
Putting in a septic system was an interesting project there
Do you know of any web pages the list the geological survey maps?<!----><!---->
Thanks<!----><!---->
Ken<!----><!---->
<!----> <!---->
Do you know of any web pages the list the geological survey maps?<!----><!---->
Sadly, I don't; it's just been too long since I needed anything other than my tattered old hard-copy map for Dallas Co.
Oh, the things you can learn in a decade or so; and just as easily leave behind almost unnoticed.
I know there's likely to be one, a fragment of it generally shows up on the soil boring report for commercial work.
{Ding! <eureka moment>} As you narrow sites down, check with the local pool guys--they will know (if from bitter experience) about sub-surface conditions.
I hadn't even thought about septic--that blackland prairie has really, really, really, crummy perc rates. Make a person spend more than a few dollars on water efficiency/recovery or the like, now that I think of it.Occupational hazard of my occupation not being around (sorry Bubba)
For USGS maps go to the source:http://store.usgs.gov/Delorme sells books of topo maps for each state:http://www.delorme.com/Often local office supply outfits that sell to surveyors, etc, will have a selection of local USGS maps.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
(And lots of bookstores carry the DeLorme book the state they're in, and nearby ones.)
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
Tom, forgive me, but what does PAHS stand for? I recently saw a new home built with polystyrene forms, using rebar and poured concrete inside the forms. Supposedly this was an R-50 wall, and the polystyrene had plastic vertical pieces that could support drywall.
I'm not suggesting attaching drywall directly to extruded styrofoam in a basement because of fire codes and short burn time of that material (in upstate NY you have to cover the styrofoam with drywall and keep a 1 and 1/2 inch gap).
At any rate, may I respectfully suggest that the gentlemen go to the building science coporation website to look up energy efficient building wall assemblies in his particular climate. It's very detailed, but informative on this subject.
Reed
>Supposedly this was an R-50 wallLots of people make claims for wall assemblies that aren't backed up by any sort of tests. Any R value, in absence of any other information (temp, humidity levels, wind, etc) is potentially deceptive. People talking about R values in excess of 30 or so, myself included, are usually talking "equivalent" R-value, which a cynic would say means it's equivalent to whatever the marketing guy says it should be to sell the most. It certainly isn't the literal aggregation of the individual materials. For example, 8" concrete with 2" foam inside will have the same literal R as 8" of concrete with 2" of foam to the exterior, and yet they will have very different performance in most climates. So take R-50 with a grain of salt, and look to characteristics other than R, including air infiltration rates, moisture control, structural characteristics, pest resistance, ease of construction, ease of maintenance, appearance, longevity.To the original question, "most energy efficient" is deceptive. 48" of concrete with a 6" exterior insulating layer might be the most efficient (to pick arbitrary numbers), but fails on other characteristics, including cost of construction. A house is a holistic structure, where you're balancing a lot of competing factors, and where "most efficient" might well vary with the location, the neighborhood, and the site characteristics. That said, those of us who favor interior mass with continuous exterior insulation--in all it's forms and variations--tend to be extremely happy with our results and quite happy to stack their performance against all challengers. Ultimately, I focus on "comfort", with the goal that my clients achieve the highest measure of interior comfort, while also being comfortable with construction costs, maintenance costs, and appearance.
Hi Reed,
Passive Annual Heat Storage (PAHS) to which I posted a link just a little further along this thread. Here it is again:http://www.axwoodfarm.com/PAHS/UmbrellaHouse.html I've been harping about this subject for so long here that I thought by now I'd put everybody to sleep. Apparently not. Basic idea is a totally passive heating/cooling system. No moving parts, nothing to maintain or repair, ever. Pretty easy to live with.
Cloud's explained the pitfalls of taking all R claims seriously. Think I made reference a post or few ago about the time when ICFs were claiming R50, as in distant past. Far as I knew, until you mentioned it, nobody was that foolish any more.
Which certainly is not to denigrate ICFs, only misleading marketing. I don't use them but freely recommend them if my methods are inapplicable.PAHS Designer/Builder- Bury it!
The best? The most efficient?
I don't think there's any question. It's PAHS (yup, sending you back to VaTom!)
I built our place starting about three years ago. We've been in for two years. Costs little to heat and cool. It's a frame house, but low budget dictated many of our choices and I wasn't familiar with PAHS at the time.
I will say that if you build an above ground structure in your hot climate,
make the outside white (in hot climates this one thing may be the easiest to do with the biggest cost-to-gain ratio and white paint actually lasts longer than colored),
do not use a tile roof! (they absorb the heat during the day and radiate it down on you during the night while white steel does about the best at reflecting the heat),
point the garage door north or south (not east or west which capture heat at the worst times),
build with a large roof overhang (to shade the house),
pay extreme attention to sealing the house (if not icynine sp? then lots of caulk and squirt foam),
consider using as many non-venting windows as possible (they are naturally tighter than venting types),
use radiant barrier installed on the underside of the top chords of your truss roof system (it's inexpensive and you can feel the difference),
overdo the attic insulation (we have about R75, if you use blown in and do it yourself the cost of the extra is very low) consider a deep well geothermal heat pump for cooling and heating, and that's about all that pops to mind immediately.
I used to build in the PHX area and studied up a bit on research done by the U in Tempe, that's where I learned some of this. Some of the rest I learned here at BT, where, of course, everyone is in complete agreement about all these issues. ; )
Best of luck to you in your project.
"Doubt is not a pleasant condition, but certainty is absurd."
~ Voltaire
http://www.cloudhidden.org/
"When we build, let us think that we build forever. Let it not be for present delight nor for present use alone." --John Ruskin Laminate is just a picture of hardwood printed on countertop for your floor.We can imagine something that only exists in our heads, in a form that has no measurable, tangible reality, and make it actually occur in the real world. Where there was nothing, now there is something.
Forrest - makin' magic every day
OTP,
Style, that's right style. What style of home will you be happy with and at the same time fit in your neighborhood?
I personally like and have used SIPs, the designs that are possible are nearly endless and construction techniques are common.
IFC's are also common in my area. For walk outs and exposed foundations they are really good, I think the insulation is overkill when used below frost. Thermal mass is captured between the insulating layers(defeats the purpose), unlike your drystack CMU with 4" exterior insulation. Also IFC work best in big rectangular shapes, corners and angles can be done but seem to add to the cost.
The information on overhangs and colors is excellent. If you can design this into your home so it fits and doesn't look like an after thought you will have an energy efficient home you are glad to own and happy to live in.
Garett
Two feet of styrofoam insulation, and five feet of dirt.
Well here's a few thoughts thought.
Consider 9' or 10' ceilings. Since most energy loss is through windows, get tall ones that are triple glazed, double hung, and insulated. For 3 or 4 months out of the year you can open the bottom and the top windows and get natural convection flow. Air in at the bottom and out at the top. Lots of ceiling fans to keep the air moving. Also consider a variable speed attic fan and roof vents.
If brick veneer, then make sure there are plenty of weep holes at the bottom and an air gap behind the brick with the gap venting into the soffit and up into the attic. Have plenty of soffit venelation (Hardi perforated soffits are good). Also, 3/4" reflective foil styrofoam sheathing behind the brick. FYI - brick, like asphalt roofs, produce a heavy heat load in the summer.
Also, look into geothermal heat pumps. The kind that have no outside coils. Their talking a SEER > 30 for these things. One detraction to this is the high electricity cost in Texas. Another is you just about have to live out in the country to do one. Heat pumps work well in Texas, but the electric rates might make one more expensive to heat with in the winter.
And, lots and lots of big shade trees!
PlaneWood by Mike_in_Katy (maker of fine sawdust!)
PlaneWood
I have been going through some of the same questions presented in this thread about an efficient energy home plan. ICF, Sips, Mooney wall etc...
The question that comes to me is what effect does the exterior have on the building shell? Stucco is not very common around here but most available lots require masonry exteriors (at least 80-90%) with brick being the most common. Again I understand that this mass is not connected directly to the building shell but surely it has a large effect versus Hardie planks exteriors.
Second thought regarding concrete mass-- what about dry stack concrete block filled with grout and rebar and exterior foam insulation? Cost effective?
Thanks in advance for your thoughts
Skin should be separated from wall mass by insulation, otherwise the mass won't work very well. I used copper for zero maintenance plus low cost. It's also used for cooking pots as it transfers heat well, but that has nothing to do with my shell.
Starting with block and trying to turn it into reinforced concrete won't save you anything but the formwork. Certainly no money. Formwork really is DIY friendly. Did you notice the book recommendation? I'd never done any before this place.
PAHS Designer/Builder- Bury it!