What is the ROI and payback on an R-30 wall in Zone 5?

Ok now I'm stressed, so you're saying that in some situations, a 2x6 wall could be WORSE than a 2x4 wall as far as moisture goes? Sure, I'd love to save the expense but I've always thought more insulation is better...

Besides providing the required insulation properties necessary to maintain a comfortable indoor temperature with minimal use of cooling/heating energy, a well-designed building envelope (e.g., ceilings, floors, and walls) will accomplish two other important design objectives: 1) keep water and water vapor from getting into the building assembly and 2) allow any water or water vapor that does manage to get in, to get out as quickly as possible.

So from a moisture issue perspective, it is not the thickness of the wall as much as the specific wall buildup and the actual climate that the building is located. You might want to read the associated instructions and play with this software to gain a better understanding how this works:

Borst Building Assembly Moisture Analysis Software

This software is based on the 2013 American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Fundamentals Handbook historical steady-state dew-point or Glaser methodology for evaluating moisture accumulation and drying within building envelopes.

I will definitely take a look at that, thank you.

It's unfortunate that I can't simply rely on a building contractor to know these things, isn't that why a general gets paid? It seems around here, they earn their percentage just by managing subs.

I just found a thread on ICF contractors in my area. Sounds like those make a ton of sense for the basement, is there any reason to not use them on my main floor as well (Cost I'm sure, but other reasons?)

Ideally (?)yes; they should know how to build the house! Unfortunately there aren't that many builders that have caught up to Building Science yet, and they are still building houses pretty much as they've done it for one hundred fifty years. You might contact some energy auditors in the area and ask them if they are familiar with super insulation techniques, and if so, what builders are they familiar with that are also familiar. Ask at the bigger lumber yards also. This stuff is critical, so don't just assume that anyone will build it right; rather make that a key part of your GC search. Ask around; talk to people they've worked for; search online for knowledgeable contractors in the area. It will be a PIA, but it will be worth it!

Posted By rgonyer on 09 Dec 2015 12:21 PM
I just found a thread on ICF contractors in my area. Sounds like those make a ton of sense for the basement, is there any reason to not use them on my main floor as well (Cost I'm sure, but other reasons?)

Beyond cost, No reason at all.  Is it the cheapest way to build a house?  No, but IMO, they do have distinct advantages.  That is what I am doing, footing to roof ICF, 8" basement and 6" main wall.  It would be easier in your area I think as you are in a lower seismic zone.  I am in D2 so lots of rebar and some extra engineering for us, but nothing insurmountable.  I am even using a inward brick ledge/corbel to hang the floor from.  My concrete guy once quoted me around $10 per square foot of wall area for the unfinished wall(materials cost, no siding windows ect).  So far the numbers are indicating my basement wall just over that(has the corbel and added engineering) and my main wall just under that, but I am providing all my own assembly labor and only contracting the actual pours.      

Posted By BadgerBoilerMN on 08 Dec 2015 10:52 PM
What is the ROI and payback on an R-30 wall in Zone 5?

Depends on how you do it, and how much mechanical system cost gets displaced. In new construction it can be remarkably cheap to hit that performance point. It's a cost-adder, but that cost is subsidized in the tax code, and on a cash flow basis it can be the same or even lower than a code-min house if the house is being heated with fuels more expensive than natural gas. And the payoff in comfort & resilience is immediate.

You might as well be asking what is the ROI and cost adder of a full-on hyrdonic heating system with micro-zoned radiant floors over a cheap condensing gas 1-stage hot air furnace single zone? There's no simple answer.

But with the higher-R building envelope the lifecycle utility costs will eventually evaporate as the installed cost of the PV required to take it to Net Zero falls ever lower. Betting on the high-R enclosure is an option for taking advantage of that lower future cost of solar once it's cheaper than anything else, and option that you don't have if going code-min.

Those lower price points that are going to happen, and sooner than most of us think. Behind the meter batteries are on a similar learning curve too. It's already financially rational to quit the grid in Australia, where the sun is strong and the retail electricity prices are high. But the price of PV + battery has to only drop by half for that to be true for most of the US. Every time the installation volumes double, the installed cost of PV drops by 25%, and the doubling time is now less than 2 years.

Even conservative estimates of the cost of PV + battery in 2030 come in under the average residential retail rates in the US right now, and at current grid-retail pricing it's the marginal cost of heating your house with current technology air source heat pumps is only slightly higher than heating with condensing natural gas. Gas prices have nowhere to go but up, but PV + battery prices are still seeing logarithmic decay in cost over time, at a fairly short time constant. The crossover is coming, and probably before 2030. But even before quitting the grid becomes financially rational(if still not a great idea, unless the utility companies and their regulators screw the ratepayers), grid-tied PV + heat pumps are going to beat condensing gas on a lifecycle basis.

Everything above should be considered, but also:

You can build good, cost effective walls with 2x6s, cellulose and 2" of EPS on the outside. Nat gas is hard to beat and I expect that geo is out. Radiant floor is nicer than forced air, but note that in a better sealed and insulated house, the difference is reduced. I'd orient the roof to accommodate solar panels, even if you aren't going to install them right away.

Posted By rgonyer on 09 Dec 2015 12:10 PM
I will definitely take a look at that, thank you.

It's unfortunate that I can't simply rely on a building contractor to know these things, isn't that why a general gets paid? It seems around here, they earn their percentage just by managing subs.

No that why architects and engineers get paid. The contractor gets paid to install the design and that includes managing the trades, which he gets at a lower price point then the diy so the over all cost is not much different.,

That's assuming the builder uses architects and engineers- many don't. Building code enforcement is pretty lax in my area, and homes are going up all over the place that don't look any different than homes from decades ago. I'm still seeing 2X4 walls without exterior foam. Sure, we have a mild climate, but c'mon. I'm in SC, and built ICF. I'm not sure how much it cost me over stick, as I did much of the work myself, but for us, it was worth it. The house is snug and quiet. Our utility bills are tiny for an all-electric home, and the comfort is a very real thing. The temperature is very even all over the house, and very stable. We generally run a single 12K mini-split for the entire house. It's December 10, and we haven't run our heat yet this year. ROI isn't everything, and we're pretty poor folks.

FBBD: You're right, I hadn't thought about that. But what jdebree said is certainly true around here. A GC around here typically has 4 or 5 "typical" floor plans they use, and they try to talk you into one of those that they will modify slightly to your tastes (minor floor plan changes, interior/exterior finishes, etc). A county stamp on the drawings is all that's required.

We've been working with a designer at a lumber yard who has created a floor plan for us from scratch based on our desires. The next step when we finalize the floor plan, he'll create a detailed set of plans that will be submitted to the county. No engineer or architect is required.

Unfortunately when we started, energy efficiency wasn't really in our minds but luckily we thought about it now and not after we had a detailed set of plans made up. Now we're trying to either maximize the plan we have even if it requires some additional changes, but the question is how do we get the best energy efficiency "stuff" into the detailed drawings.

If we have to start over, it's not a huge investment. We've only paid $500 so far. On the flip side, we have a lot of time and energy devoted to getting the floor plan the way we like it. Starting over won't be popular with the Mrs.

Having said all this, we'll likely live in this home 15 to 20 years (maybe longer, but I think when we retire, we'll move somewhere a bit warmer in the winter ) So with natural gas so inexpensive, we can't justify building a $600,000 house versus a $400,000 house.

I firmly believe ROI isn't everything, and comfort is VERY important to us. Our current home that was built in '99 is 2x4 exterior walls, fiberglass batting, 1/2" drywall, OSB, TYVEK wrap, and vinyl siding. Our furnace runs a LOT even when it's not that cold out, and we both have breathing issues all winter long typically. Cost of living in this area is very low, so there just isn't a lot of drive yet for people to consider alternative building methods.

I REALLY like the ICF the more I read about it, and I've always liked the idea of radiant floors for comfort. If I don't get 100% ROI on those, I'll be ok with it because the increased comfort will be worth it. I also like the idea of PV + Battery, but we do have extended periods around here of gloomy/cloudy days. How will it perform in those situations?

If anyone is interested to see the current revision of the floor plan, I could post it. And again I thank you all for your input!

ICF is a good choice for many reasons. So is hydronic radiant floor heating which can be accomplished at a bargain compared to other heating options if you are already pouring a concrete slab. Constructing a great building envelope is likely the best place to apply your funds.

ICF performance can vary drastically depending on the location, specifically the seasonal daily temperature profile at the location. ICF performance increases with increasing diurnal temperature about your indoor temperature. You might find our ICF performance software useful in assessing how well ICF will perform in your location:

Borst ICF Performance Software

What jdebree says is certainly true most places around the country. (for a diy'er, he's a pretty astute fellow ;-)) And there is nothing really wrong with it. The point is, you can't blame the GC for doing what you accept. You must not have liked one of their plans, so you are developing one of your own. I'll bet any one of the GC's are willing to bid on your plan, wither lumber yard variety or from an architect. Sort of like going to a pharmacist or a doctor for health care. Each has their place ;-).

You don't have to start over. Most of the hard work is done if you have a design you like. Just adapt it to or add some better methodologies.

ICF is THE best house you can build. It doesn't rot, mould, shift, twist, turn, shrink or swell. What you have today, you will have in fifty years. Unlike wood construction, it will stay tight over its lifetime.
An ICF basement in most areas is comparable to the cost of a cup foundation, once you add in the cost of insulating the inside of a cup foundation. No doubt, going three storeys of ICF (like mine) is a little more then framed walls with some additional foam.
ICF performance is great, in any climate, regardless of diurnal temperature swings.

I totally agree with your thoughts on ROI and COMFORT. Pick what works best for you in your situation. Sometimes spending five cents of tomorrows money make more sense then spending all of it. Like putting pex in a concrete slab, even if you are not going to go full out radiant heat right now. It is such a small investment and it will be waiting for you when fuel cost change (or when you want to develop a basement). Spending money on insulation under a slab, doesn't require any changes to your design but from a ROI AND COMFORT, it's a no brainer.

" I also like the idea of PV + Battery, but we do have extended periods around here of gloomy/cloudy days. How will it perform in those situations? "

Nobody is suggesting that you go off-grid, but as time of use and compensation for power exported to the grid become part of the financial structures of utilities or as net-metering rules change battery storage may become a valuable asset to have on your side of the meter. The annual PV output for any US location easy to estimate using tools like PVWATTs:

http://pvwatts.nrel.gov/

The upcharge for hitting the ~R30 whole-wall etc performance numbers is nowhere NEAR another $200,000. There's a builder at the cold edge of US climate zone 5 in MA who regularly turns out Net Zero houses in the 1500-3000' range for well under $200 per square foot, many well under $150K including the PV array. (So a 2000' house would run less than $400K.) eg:

http://transformations-inc.com/press/PDF/DOE_Challenge_Home-2013_Winner_Production_House.pdf

http://transformations-inc.com/press/PDF/DOE_Challenge_Home-2013_Winner_Custom_House.pdf

Note: The installed cost of PV has come down considerably since those houses were built, and if you're building in 2017 after the step-down in income tax credit subsidy it would still beat the numbers on those houses from a few years ago.

I have some nit-picky issues with the amount of XPS and spray foam he uses, and the lack of smart vapor retarders on the interior. I suspect a Carter Scott-approach house done with EPS and cellulose could come in cheaper, greener, and more resilient than his Devens MA development, but you don't have to spend anything like $600K to have a high performance Net Zero Energy house in zone 5 that could be heated & cooled by a couple of mini-splits. There are now many dozens, possibly 100s of existence proofs in my US climate zone 5 area.

Hitting those performance levels with ICF is possible, but considerably more expensive. ICF is still worth considering when you live in tornado alley, but the value isn't about the thermal performance, which tends to be hyped to excess by the ICF vendors. A typical 2.5" + 2.5" ICF wall comes in at about R22 whole-wall. The thermal mass of the concrete doesn't magically boost performance to R30. It would need at least an inch more of exterior foam, or a non-structural batt-insulated 2x4 wall on the interior to get there. But an ICF will withstand a 100 mph 2x4 projectile a bit better than a foot-thick double studwall foam or cellulose wall.

ICF is certainly a great choice. However, our 66R Summer and 63R Fall performance is significantly better than our R21 Winter and R21 Spring performance. While we consider the average annual R43 performance to be quite good, this average annual R-value and the lower Winter/Spring R-values could be bettered using other wall envelope designs. Still, the other additional ICF benefits clearly make ICF a winner in our opinion. Further, the cost for a single story ICF residence should be less than the cost of comparable R-value wood construction.

Calgary has very little diurnal swing and yet ICF outperforms almost anything else. We do occasionally have chinooks or a DeCaprio calls them, "sudden climate change".

But as long as we agree that ICF is a superior building model, I don't mind disagreeing on this. I just don't want people thing that ICF doesn't work when in cold climate as has been expressed by some who don't live here.

I was hoping to be able to post an attachment of the floorplan as a .jpg, but it looks like the forum does not support that. I'll see if I can host it somewhere and attach a link.

DAna - as the cost of any construction can vary dramatically across the country, it might be better to express the cost of upgrades as a percentage adder to the base building cost rather then an absolute number. In Calgary they don't even build code min. at 200/ft so to use that as a base makes little sense. I think you are suggesting that a well built home c/w with PV doesn't have to add more the 20 to 30% and maybe much less. This could still be over 600,000 in some parts of the country.

I would expect we would be near the low end of the scale.

As an example, in a very high end good school local neighborhood, we looked at some brand new finished homes recently. 1750sq ft main floor ranch, probably 70% of the basement finished to the same level as the main floor (Mid/high end, very high coffered ceilings, granet, hardwood/tile flooring throughout, etc). Some stone veneer on the outside but lots of vinyl siding. $415k asking price including the building lot. That's in a higher end city limit area. We are in a rural area with low taxes and we already own the land outright.