Note that passive thermal mass cooling increases the discomfort caused by humidity. So super insulate/air seal/ERV/reduce solar gain/over-cool with AC while the sun shines/store cool from night air/whole house + ceiling fans/etc and then:

1) use batteries (more than you think) to get some non-sun hours cooling/dehumidification or,

2) implement a chilled water AC system (with a large (1200 gal?) water tank and fan coils) that can be fully charged while the sun shines. Chiltrix (< 2KW for 2 tons)? Import a Japanese model from the UK?

Dehumidification can be stored (in desiccants), but I haven't seen a practical example (bentonite clay in gabions?)

Consider a small generator running on propane or diesel. Retain the waste heat in the Winter.

Reflective paint? Hmm. I was going to go for a natural white brick/stone for the outside. I just don't want to have to worry about the upkeep that paint requires down the line. Looking for very low maintenance here. Which is why I want it to be built strong and right the first time.

It also looks like I will be reducing the square footage to better suit my needs and my budget. I don't think One person needs all that extra space anyway. I was told by a builder that for ICF, the cost to build is roughly 120.00 - 140.00 per square foot. Is this reasonably accurate? Can anyone confirm this?

That seems crazy high to me. For 6” ICF we ROM estimate about $4/sf for ICF block, $3/sf rebar, and $3/sf for concrete. So about $10/sf of wall area for materials in our SoOR region. Professional ICF installation labor rates can vary significantly by region and by complexity of design, but mostly vary by regional competition/demand. Installing and pouring ICF requires some knowledge/experience and requires some specialized tools (e.g., bracing/scaffolding, vibrators, foam adhesive gun, foam hot knife for electrical/plumbing, etc). However, installing and pouring ICF is way easier and way faster than conventional 2x framing.

I was told by a builder that for ICF, the cost to build is roughly 120.00 - 140.00 per square foot. Is this reasonably accurate? Can anyone confirm this?

Sabotender, I think 120/140 per square foot is probably total house cost in realtor/appraiser language. In other words ICF, plus foundation, plus roof, plus cabinets, plus driveway, plus stainless steel dishwasher, et cetera.

You've got a set of criteria that are not that common. Dana knows what he's talking about - if you really want to go off grid then you really need to consider how to make that become a reality in your climate. However if that was just a dream, and a nice energy efficient house would be good enough, then that's a different story.

You don't know just how much you don't know.

Cheers!

Jelly: That may be so, but the fact of the matter is that I do NOT want an adobe or pounded earth home. Sorry to be so direct, but it didn't seem that certain hints weren't being taken. I do appreciate the information that he has provided, but it seemed as if he was really trying to push adobe and/or pounded earth on me. Let's not talk anymore about it, just now. Thanks.

Now, regarding your comment on the price per sq ft. I see. Well, I am mostly concerned with the actual construction of the house, like the roof, foundation, walls, etc, and not the appliances/fixtures/finishings, as I would be buying those myself, and having them available for the installers when needed.

sailawayrb: if I sent you some designs that I have been working on, would you mind giving me a rough estimate on building costs? I have an appointment with an architect Monday who is going to look at it too, because I would need to have it...what is the word? Professionalised? You know, drawn up with real dimensions and whatnot. I've really scaled it down from what I had in mind before. Removed some rooms that I don't need (since this is for a single individual). If you do agree, I just want you to be prepared for it's VERY modest design.

Overall home building costs are very dependent on the region, due in large part to labor cost differences. You won't be able to compare the cost to build a home in the Pacific NW with the cost to build a home in Texas. As an example, brick installation is relatively cheap in Arkansas because we have many brick plants nearby and labor costs are low. Texas is probably similar. In Arkansas, it costs about $4/sq ft of wall area to have brick installed. In many parts of the country it is easily double that figure. Interior finishes and fixtures can have a big impact on building costs - things like cabinets and counter tops can easily vary 100% from one home to the next based on choices of materials. Flooring costs are similar. Kitchen and bathroom fixtures are similar. And what about those soft panels you want installed on the walls? How much do they cost? With ICF foam on the interior of your walls, you will likely have to have 1/2" drywall or an equivalent 15 minute fire barrier installed first.  You can install those soft wall panels over the drywall, but you can't skip the drywall. Most home builders will not be familiar with those or know how much labor it takes to install them. How is your roof going to be constructed? What materials? You really need to get with an architect in your area to work out these details. They should be familiar with local building costs and practices and should be able to give you a rough construction cost for your home.

In Arkansas, a typical custom built single story 2000 sq ft brick home (heated & cooled area) on a concrete slab with attached 2 car garage using wood frame construction and cellulose insulation and insulated windows meeting or exceeding code minimums with custom hardwood cabinets and granite countertops and 16 SEER 2-stage 3 ton heat pump would cost approximately $90/sq ft of heated and cooled area to build turn key or ~$180,000 for this example.  In other parts of the country, costs for this same home could easily be 50% higher.

I do think that ICF walls are the best practical compromise to meet your goals considering the availability or lack thereof of competent builders of other high mass alternatives in your area.

I sincerely appreciate the vote of confidence, but we are totally booked up for this season and we also don’t build in your area. My husband was not happy with me about recently accepting a couple of HR design jobs after we officially stopped taking on new clients back in September. However, more importantly for you, any estimate we would provide wouldn’t really do you any good as it wouldn’t be applicable because of factors unique to your area.

I would highly recommend that you continue doing research to learn as much as you can about every critical construction element, but start working with an architect familiar with any unique construction issues in your area (and an engineer too if you start getting away from the prescriptive code)...and then carefully listen to and follow their recommendations. Once your architect has completed a good set of construction drawings, get bids from at least three local builders in your area (five bids would be even better). The lowest and highest bidder are often not the best choice. Carefully check out bidder credentials/references and select a contractor to accomplish your project.

You are doing all the right things by asking all the right questions and taking the time to learn/decide before just jumping into the construction phase. It is very expensive to make changes once construction begins and you are locked into a contractor. Of course, us contractors don’t really mind making changes, but you certainly will. Good luck with your project!

sailawayrb: Hmm? Oh I wasn't suggesting that you come all the way to Texas and build the house for me, I am just trying to get real cost estimates, and when you say that the estimate that I was given from that one builder was on the high side, it makes me a little nervous to even consider using him in the first place. I just wanted to know what you thought about my floor plan. As I mentioned, I have an appointment with an architect tomorrow who is going to look over my plans and hopefully give me a good idea over things.

arkie6: Afaik, the softwalls are just fabric covered fibreglass paneling and are finishings in their own right. Drywall is not required to be under them. They are usually installed in finished basements, for example. I think some people call them...acoustic paneling? I know that building costs vary depending on area, but I plan on having a big hand in pricing out the costs of internal fixtures. Anything that I can purchase myself, I will do so. I have heard that many builders may have 'deals' with certain suppliers so they use their product, which may or may not be the best price OR quality.

Posted By Sabotender on 28 Feb 2016 01:27 PM

arkie6: Afaik, the softwalls are just fabric covered fibreglass paneling and are finishings in their own right. Drywall is not required to be under them. 

Building codes require a 15 minute rated thermal barrier between combustible foam insulation and occupied areas of a home.  1/2" drywall qualifies as a 15 minute thermal barrier.  Do those softwalls qualify?  If not, you will still need a 15 minute thermal barrier installed to meet building code requirements.

The finishing panels have information as follows: ASTM E84, Class A. Flame Spread: 15; Smoke Developed: 40

I work with fabrics every day, I would check into what chemicals are used, if any, to get the fabric to pass the testing.

Some I deal with are irritants and could affect indoor air quality.

ChrisJ

I think there are different fabric materials that can be used. I was going to go with an inexpensive polyester.

"Let's not talk anymore about it, just now. Thanks."

Actually Dana was being polite. You are attempting a difficult project with a modest budget, an even more modest understanding, and what strikes me as insufficient gratitude for someone asking for help.

You need to start at the beginning. Call the county appraisal office and ask them what they consider the average cost per square foot for new construction. Price a solar system, batteries, a backup generator and the electronics to automate it. These folks are just down the road in Austin. www.texasoffgrid.com. Add these costs and present the total to your lender to see what's doable. (An Energy Star mortgage will finance 120 percent of appraisal for houses that use 30 percent less energy than average.) You now know how much you can borrow and how big a house you can build. You'll also have an idea of what premium features you can add, if any. The builder you asked about ICF found a clever way to NOT tell you how much extra it costs.

There are many ways to build without wood. Austin is a hotbed of energy design innovation. Do some research. Then come back.

Posted By Sabotender on 29 Feb 2016 10:32 AM
The finishing panels have information as follows: ASTM E84, Class A. Flame Spread: 15; Smoke Developed: 40

None of that indicates the panels are a thermal barrier. Here is what the 2012 International Residential Code (IRC) says: R316.4 Thermal barrier. Unless otherwise allowed in Section R316.5 or Section R316.6, foam plastic shall be separated from the interior of a building by an approved thermal barrier of minimum 1/2 inch (12.7 mm) gypsum wallboard or a material that is tested in accordance with and meets the acceptance criteria of both the Temperature Transmission Fire Test and the Integrity Fire Test of NFPA 275. http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_3_par211.htm

But toddm, I'm not in it for the gratitude! :-)

Seriously, getting it right and under any sort of budget constraint requires much more attention to the building design. While radiant floors, ICFs, ground source or air source heat pumps and PV are all really great technologies in the right context, everything changes when you're going off grid. Off grid you have to be your own electric utility, and you have to capitalize and pay for that electric utility up front. If you get it wrong, it's VERY expensive to upgrade. With an infinite budget you can afford to get it wrong and throw several 10s of thousands at more PV and battery, but that would be a bit silly since it's possible to design-out most of the load with the building design.

The cheapest performance booster to the project is to design out the summertime solar gain with window orienation, sizing, and type. Then next cheapest performance booster is more thermal mass located the "right" side of the insulation, which is partially defeated with ICF. The cheapest thermal mass is site sourced dirt & rocks. It doesn't have to be rammed earth or adobe, although those method work well. You don't have to love it, you don't even have to look at it, but it's effective, and most importantly COST effective. Every ton of cooling you can peel off with thermal mass pays off in lower PV, battery and heat pump requirements. A ton of dirt (or 10 tons of dirt) is a lot cheaper than a ton of cooling provided by a PV (or battery) array. High mass construction has been a standard solution for millennia in warmer climates for a reason- it works, with or without electrical grids, or mechanical heating & cooling. With modern windows and better thermal design & simulation tools it can work even better.

Before embarking on this path, DO try to find a few off-grid homes in the area to at least visit, if not actually live in for a weekend or a month, and discuss the design features with the owners/occupants/designers if you can.

Remember - off-grid electricity while the sun is shining isn't all that expensive (long term). Off grid and off-hours is and you want to do much more than most to reduce usage.

If nights are uncomfortably hot and humid (I haven't looked at your climate) then consider using AC in a small, low mass, super insulated sleeping room and let the rest of the house get warm. Then the thermal mass only needs to get you through the evening.

Rocks can be cheap passive thermal mass with good air flow.

Yup! Dirt & rocks thermal storage is a lot cheaper than battery storage, even when leveraged through a heat pump.

Anything that requires electric power to retrieve stored thermal energy after dark is expensive energy too.

Sensible temperatures at night can be managed with heat pump/AC operated only during daylight hours if you build in sufficient thermal mass. Latent loads can probably be managed the same way, at least most of the time.

toddm: I am not going to apologise if you think that me saying that I have zero interest in adobe or pounded earth. I have made multiple comments that ICF is most likely the best thing for me as far as budget and availability in my area. If you are going to constantly tell me what I should be getting instead, but it is not readily available in my area, or, more importantly, not what I am interested in, that is your problem, not mine.

In addition, I am extremely thankful for all the insight that has has been provided to me. I say 'thank you' as often as I can to let people know this. Furthermore, I have been doing loads of research, and I just found out today that what I need is not an architect, but a structural engineer.

I already have a builder who is interested in constructing my home, but he needs concrete plans so he can give me a real quote for construction. I am in contact with a structural engineer now. We have a scheduled meeting tomorrow.

arkie6: I will send an email to the manufacturer to make sure that these panels are qualified, because I would prefer if my home did not include any sheetrock/drywall.

Dana1: I have removed MANY of those items out of the equation. Also, I have taken a lot of your suggestions to heart. I have reduced the floor plan considerably. I am going to use a wood burning furnace, solar water pre-heater, on demand propane water heater, Ductless Mini-split system (just one, since the square footage is so small now), 10KW solar power bank, and enough batteries for a reasonable backup during dark hours. You have very VERY good ideas. The only one I was not interested in was the adobe and/or pounded earth. I won't be investing in radiant flooring since I won't need one.

I will gladly show pictures of the completed floor plan when the structural engineer has finished drawing it up, as well as the true cost to build.

Sounds like an interesting project. If it is a very tight house, wood smoke odors are more obvious. I haver an older homes which we are in the process of tightening up & we have replaced the oil furnace and the propane heat for minispits. I kept the wood stove. Problem is that it is always very comfortable in the house so I have no desire to carry the wood or light the woodstove. Wife notices how much cleaner the walls stay. On the few occasions when we have lit it, the house comes up to temp very fast, so we never add wood.

Oops, did I say 'furnace'? I totally meant 'stove'. My mistake ;-) I don't think that the smell from a wood stove would be any worse if I were to have a fireplace put in (which I am not, btw)

Yes, it is indeed an interesting project, but I am determined to be a homeowner. I refuse to rent for the rest of my life.