# Most Efficient In Home Heating



## brewerfan22 (Sep 17, 2014)

Hey all,
I was very happy to find this website as I am in between heating options for my future home. My significant other and I are looking to build a home within the next two years and are trying to be as efficient as possible and use as little "on the grid" resources as possible. We are looking to build in Central Wisconsin and as I'm sure most of you know it can get pretty cold up here (last year we had solid -40 weather during the winter). So I figured before I put the pen to the paper designing rooms and features I would take suggestions from those experienced with the different heating methods and their efficiency to help me with this build. I am an open book as far as concept design goes and the house is looking to be 1750 sqft or slab on grade with 2x6 walls and closed cell spray foam insulation if this helps. Thanks for any input ahead of time!


Zack


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## semipro (Sep 17, 2014)

Zack,
Welcome to the forum.
My thoughts:  the best thing you can do is minimize heating requirements.  Its surprising how little heat it takes to warm a tight and well insulated house.
Consider incorporating passive solar.  This is relatively easy and inexpensive to do when you're building new.
What you choose for heat as far a fuel whether cord wood, pellets, corn, gas, "electricity" etc. depends upon fuel availability and costs in your area as well as how much work you're willing to invest in heating.
Natural gas is cheap and getting cheaper most places.  Its hard to beat for something that you "set and forget".
If you have ample nearby cord wood sources that's an option but it takes some physical investment of labor to heat that way.
Electricity is great and lends well to later PV conversion.  There are some really efficient mini-split heat pump systems out there now.
You'll get some good advice as others chime in.
Good luck and have fun with the planning.

Edit; consider a single story open floor plan.  This tends to lend itself to flexibility for heating. Also, high ceilings are pretty but its lower ceilings that keep the hot air where its needed.

Edit2: landscaping can impact energy efficiency.  Evergreens to block winter winds and deciduous trees to the south can help with heating and cooling loads tremendously.

Edit3: with 2x6 construction you may need to add some foam panels on the exterior to get insulation values up.


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## woodgeek (Sep 17, 2014)

If I were in your place, I would read up on the 'Pretty Good House' or PGH concept at GBA.
Start here...there are more: http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/pretty-good-house
Many guidelines from knowledgeable folks, re insulation levels, they rec this:

_"Have 10-20-40-60 insulation. Hopefully these numbers are obvious: they represent a “pretty good” level of insulation in a cold climate for sub-slab, foundation walls, framed walls, and roof or ceiling, respectively."_

You will not be able to get to this level with 2x6 conventional framing and spray foam (I assume you mean in the cavity).  In conventional framing, 25% of the wall area is wood, at R-6, and the thermal bridging defeats all that expensive sprayfoam (which also might outgas nasties more than many would like).  For less cash, you can go with densepack cellulose in the cavity and 4" of foam sheet outside, to avoid the thermal bridging.  Detailing openings in the thicker wall is a small pain, but amounts to a bunch of plywood boxes anchored to the framing openings, and protruding through the foam.  The siding gets hung off furring strips outside the foam, anchored to the framing by long (and slightly spendy) screws.

BTW, this insulation level is LESS than passive house, but it represents the *current best tradeoff between energy costs and construction costs*.  Passive house is way more complex and expensive than this.

Aside form this PGH insulation level, you need to find a builder to build airtight, and willing to put a blowerdoor spec in the contract, (i.e. has done it before).  Don't worry about fresh air....it will be supplied by an HRV, just as in millions of homes in Canada.

As for heat source....it will be small.  In a Wisconsin climate, I would probably do either geo (if money were not an object) or a small propane-fired hot air furnace if it was (the usual case).  The cost of the geo will pay your propane bills for many years to come.  If you want AC, a small 1.5 to 2 ton central unit would be plenty.  If not, a single window unit in an unused bedroom would prob keep the place cool and dry.

Of course, a small cat wood stove with an OAK would probably heat the whole place, and keep the propane man away.

IIRC solar in Wisconsin is not well incentivized.  Site and orient the house to be 'PV-ready', with a large steep roof plane facing south, etc.  Then have solar put in in 3-7 years when the cost makes it a no-brainer.  Consider a metal roof on the south plane, or the whole roof.

What was the question again?


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## peakbagger (Sep 17, 2014)

Slab on grade introduces some extra challenges. Plan on burying lots of foam. I was working on a project with an engineer that is building a passive house in Portland Maine on a slab. Slabs in Maine are rare but they are on ledge. Here is a link http://portlandpassiveproject.blogspot.com/.

They are going to a lot of work to get certified as a passive haus,  a lot of the materials have to be shipped in as the local similar products don't have the right paperwork. That's why the Pretty Good House movement has sprung up, get 90% of the benefits of a passiv haus with far lower cost.


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## woodgeek (Sep 17, 2014)

You should search on "Frost Protected Shallow Foundations".  Basically a large skirt of buried sheet foam around the house perimeter, to keep the earth under the slab from freezing.  What do you have against basements?


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## dougstove (Sep 17, 2014)

The Swedes routinely build insulated slab construction, in cold climates.
It is starting to catch on here as well.
I am intrigued by the integrated foam form poured concrete construction, they are getting common in my area.
Another approach I have seen is a double-wall 2"x4" framing, with the frame elements offset to break the thermal bridging.
Aside from ideas above, building smaller is a good way to go.  Maybe shave off some sq. ft. and think about an unconditioned woodshed or garage loft for storage.


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## woodgeek (Sep 18, 2014)

Double stud wall construction works too to get to high R-values....you can make a very deep wall cavity and fill it with the cheapest and greenest insulation—cellulose. Even if you build two 2x4 walls with the studs lined up (easy to build) if there is a few inch space between (for a 12" or thicker wall) then there is still no bridging, and it is easy to brace between the two walls.  You still need to connect at top and bottom plates, usually falling back to 1/2" plywood which does have some thermal bridging.  A more modern variation, is to use engineered wood I-joists in lieu of 2x12 studs.  Again, easier for a builder to understand or mod existing plans...but the I-joists are expensive.  Otherwise, you are still spending almost double on your framing lumber.

All the above seems to be rare in the US, expensive, understood by few builders, etc, and reserved for passive house projects.  And depending on the air barrier methods, may still need foam on the exterior to keep the sheathing from rotting....so it is technically risky for durability.

The PGH approach IS conventional 2x6 framing, and the only thing weird is the window+door detailing, exterior foam wrap, air sealing details, and siding install....much simpler and cheaper to add than teaching the builder a whole new framing style and trying to find plans for it.


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## jebatty (Sep 18, 2014)

> I am an open book as far as concept design goes and the house is looking to be 1750 sqft or slab on grade with 2x6 walls and closed cell spray foam insulation if this helps.


Central WI puts you pretty close to the same temperature climate I have in central MN (47N latitude), at least as to seeing those -40'sF. Our house is 1500 sqft, single story, but with basement (you won't), pretty close to yours. If I had a do-over, these things (plus most of the other suggestions that complement) would be high on my list.

Heating/AC: not forced air, but hydronic in slab with a pellet boiler (and buffer tank) or a wood gasification boiler with substantial storage, plus mini-split heat pump(s) for summer AC as needed (probably minimal) and shoulder season heating, and also with a wood stove installed in a open, central area of the house.

Reasons: In slab hydronic is highly efficient, even heat. The wood stove would provide the supplemental heat over the slab temperature as needed, as slabs respond very slowly to warm up or cool down. Pellet or wood gasification boilers are substantially carbon neutral, wood more so than pellets (due to extra processing costs for pellets). Mini-splits use electricity very efficiently for cooling and shoulder season heating. Wood gasification with substantial storage (2000 gallons would be my recommendation) can provide hydronic heat between boiler firings, depending on temperature, from every second to third day to longer than a week. Pellet boilers can modulate output roughly between 30-100%, and a buffer tank increases their efficient operation. My bias is strongly anti-fossil fuel, thus no propane or even NG. Propane prices went out of sight last year. Wood and pellets both should be in plentiful supply in central WI with a pretty even market into the foreseeable future, and both are sustainable.

Site and build for passive solar: A southerly to SW facing houses with suitable windows and open floor plan can heat your house during the daytime on sunny days on just about the coldest days winter can offer, as it does for us right now. And with appropriate eaves your house will not be overheated during the summer. Extra building cost, if any, is minimal. A moderate landscape plan with some deciduous trees is OK on the south and SW, but not pines blocking the sun during the winter. Put pines on the north and NW to help block the cold winter winds.

Site for active solar PV: Large southerly roof exposure with pitch that maximizes solar potential for roof mount PV. Here there is a conflict with trees and shading. You need a large open expanse (site on a hill?) which provides essentially no shading from the south and as far to the east and west as you can manage. Where I live in MN the only incentives for PV were the federal 30% tax credit plus net metering at the retail rate. We installed ground mount solar last October (no suitable roof location due to shading), and I believe we now have eliminated our electric bills forever. A change in net metering can adversely affect that, but I believe technology on PV distributed systems, battery storage and other advances will make RE the game changer it quickly is becoming. 

Consider adding active solar PV now: I understand the argument for waiting, but the fallacy is considering solar a cost (focus is on short terms economic payback) and not a value. And if you have net metering, the argument also fails on cost. Who buys a car for economic payback, furniture, or even a house? or who has children for an economic payback, or goes on vacation, or does a myriad of other things for economic payback? Life is lived for things we value, not for what they cost. Active solar has high value, IMO, and I also believe it pays back. Active solar just sits there and pays you for that privilege.

Some other ideas: 1) keep your roof lines simple, complexity adds building and future maintenance cost; 2) build as maintenance free as you can afford, not only future cost savings but also time savings; 3) build with good slopes and drainage, be careful about a high ground water table and runoff from neighbors; 4) the more square a structure, the more efficient it is and also, I believe, the more usable space it has; 5) open floor plans ease heating, cooling and comfort demands; 6) small special purpose rooms can be very wasteful of everything and not very usable, build spaces for multiple purposes; 7) highly efficient windows allow more glass and really open a house up to the outside, if that is important to you (our windows are R-8, U-0.12 and more energy efficient than some of our 1956 house walls, lots of glass, light, and perception of open space in every direction); 8) locate ideally close to work, school, shopping, etc., saves lots of time and expense related to driving, all of which translates to more time for everything else.


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## jharkin (Sep 18, 2014)

Living in a very old house I dont have as much experience with super efficient modern methods to offer as some of the very knowledgeable folks who posted above.

But I do have an idea for you... Why not combine these ideas /techniques along with some of the knowledge our forefathers had but got lost along the way in the era of cheap energy.

What do I mean?

#1 - Site for full southern exposure.  Just having the house face the sun makes a surprising difference in winter even if you dont have dedicated passive solar elements.

#2 -  Trees!  Don't be like modern developments and cut them all down. Leave a lot of trees (deciduous) around the house - In summer they will provide valuable shade that reduces cooling load and then in winter they drop their leaves and let in important sun to give you solar heating.

#3 - Don't rule out multistory construction.  The singe story open plan with 87 roof lines may be all the rage today, but the old New Englanders built boring two story boxes for a reason!  Other than a dome, the box shape has the most efficient ratio of exterior surface area to usable floorspace of any building shape and has a big bonus of much lower roof area than a single story. This give s you a big advantage in lower heat loss in winter.

#4 - A variation of #3. Open concept is great for even heat distribution especially with a point source like a stove.  But if you have central heat and want to save even more by only heating the space you are using, more rooms gives you the choice to close off spaces that are not being heated.  This one is probably not such a big deal today but I point it out to illustrate there was a method to the colonials madness with lots of small rooms with low ceilings and narrow doors. The other variation on this is the late Victorian approach with a number of rooms connected by large double pocket doors that could be opened to make it all one big space or close off sections as desired.

#5 Ceiling height.  As was mentioned cathedral ceilings are a nice design element, i too love the open feeling. But they suck if heating efficiency is your goal.  OTOH for cooling high ceilings are a large benefit.  Put together high ceilings, lots of windows with cross ventilation and high thermal mass masonry construction and you can achieve passive cooling in quite hot climates - something they knew back in the 1800s and the reason why Victorian age homes have high ceilings and tall windows.

#6 Windows.  I always cringe when I drive through a McMansion development and see a house with a bunch of windows facing the road and then none on the side walls and few in back. You know these homes where all built with 24/365 mechanical climate control and artificial lighting in mind.  Again there is a reason that _all_ homes of the 1800s and earlier had a lot of windows and few or no rooms that did not have exterior walls (the only variation being that the hotter the climate the larger the windows where relative to the room). The obvious one is it decreases your need for electric or other means of lighting in daytime hours, but even more important:

In winter - Having a lot of windows, especially if they are double hung and have good thermal blinds allows you to open all the southern window blinds up in daytime and let light in for solar gain, then close the blinds at night to hold that heat in.
In summer - If you have a two story with a lot of double hung you open all the bottom sash on the first floor and open all the top sash on the second floor and let the stack effect drive a nice natural ventilation in the house.  The colonials did this with the added benefit of functional exterior blinds (often mistakenly called shutters today) that where closed with the slats opened to block sunlight but let in air). You would be surprised how effective this can be without mechanical AC.

I dont live in any super insulated house.. in fact I live in a barely insulated house. But with full southern exposure and intelligent use of a lot of windows on sunny days in this joint we often dont need the heat until it dips into the 30s or low 40s. In the shoulder season when its in the high 60s in the daytime and dipping to the 40s at night I open the windows in the day and let solar gain get us up to 75ish, then close the windows and shades at dinner and can usually ride out the night without the house cooling that much.  This time of year particularly I often have my windows open on days I'm reading that some members are already lighting their stoves.


If you put just a few of the above ideas together with these advanced building and heating technologies I think you can have an amazing house. Good luck!


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## woodgeek (Sep 18, 2014)

OK, I"m gonna disagree with Jim (@jebatty) a bit.

IF you built it to PGH standards, that would be a specific heating index = 2 BTU/sqft.HDD.  If you had 1800 sq ft and 8000 HDD in a season (for central wisc), that would be 2*1800*8000 = 29 MMBTU, about 400 gal of propane, OR 1.5 cords of wood, assuming no other heat source.  In practice, a little passive solar, body and appliance heat would supply up to half of that, dropping you safely to <300 gal propane OR <1 cord of wood per season.

At these heating loads, the problem is getting a small enough furnace or wood stove to not overheat the place.   That's why I would lean towards a small/cheap propane furnace, with ducts inside the envelope.  At these low heating loads, the blower would easily distribute heat (unlike in conventional constructions) so 'comfort' does not require hydronics or extra thermal mass.  Who would buy a wood boiler and storage to burn 1 cord per season? Rather, you would just need a small catalytic wood stove that you can throttle down, even in winter, or do one burn a day in the shoulder seasons, and use the furnace recirc to redistribute the heat (which works great in a PGH).

I am anti-fossil fuel.  But for cost of a gasifier and storage, you could get a very small geo put in, and source its juice from a PV array.  At COP=3 (conservative) it would require 29 MMBTU/3.414 MBTU = 8500/3 = 2800 kWh of electricity....only about a 2 or 2.5 kW PV panel to go 'net zero' for heating.

If budget was tight, you could build PV ready....buy your juice from a green utility for now, and then put in PV in a few years when it is even cheaper, and your bank acct has recovered.  IF you have the cash now, roll it into the build and or mortgage loan.

I also think active solar space heating is a loser in the Midwest and Northeast US.  These locations have a great annual resource (hours of sun per year) but a terrible winter resource (hours of sun in the winter) due to their weather patterns.  With PV, it makes you the most juice and money spring, summer and fall.  With active solar heating, it is DOA when you need the most heat.  PV based approaches pay better in these locations.


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## semipro (Sep 18, 2014)

woodgeek said:


> That's why I would lean towards a small/cheap propane furnace, with ducts inside the envelope.


I'm curious, why propane over electric heat pump?  Concerns over using resistance heating when temps drop?  Cost of propane heat is cheaper than electricity where OP lives? 
Electric would allow easier eventual PV conversion with no need for a 2nd fuel (propane).


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## woodgeek (Sep 18, 2014)

I'm assuming even the best minis will not hack it at Upper MIdWest winter temps, and so would only provide a shoulder season solution.  Elec resistance would require 9000 kWh.  IF minis covered 60% at COP=2 and the other 40% was resistance (a wild guess), that is still over 6000 kWh/year.

I also thought propane was 'cheap' in the midwest, when it wasn't spiking.  And demand would be low enough that 1 tank would cover a season, so no buying in the winter.

It kills me to rec a fossil-fuel, but the OP would need to pencil out the numbers on geo/minisplit/propane to see what worked best, I can't rule out propane on its face.


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## Dune (Sep 18, 2014)

woodgeek said:


> OK, I"m gonna disagree with Jim (@jebatty) a bit.
> 
> IF you built it to PGH standards, that would be a specific heating index = 2 BTU/sqft.HDD.  If you had 1800 sq ft and 8000 HDD in a season (for central wisc), that would be 2*1800*8000 = 29 MMBTU, about 400 gal of propane, OR 1.5 cords of wood, assuming no other heat source.  In practice, a little passive solar, body and appliance heat would supply up to half of that, dropping you safely to <300 gal propane OR <1 cord of wood per season.
> 
> ...



A wood boiler gives you hot domestic water, and propane is a fossil fuel.


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## Dune (Sep 18, 2014)

brewerfan22 said:


> Hey all,
> I was very happy to find this website as I am in between heating options for my future home. My significant other and I are looking to build a home within the next two years and are trying to be as efficient as possible and use as little "on the grid" resources as possible. We are looking to build in Central Wisconsin and as I'm sure most of you know it can get pretty cold up here (last year we had solid -40 weather during the winter). So I figured before I put the pen to the paper designing rooms and features I would take suggestions from those experienced with the different heating methods and their efficiency to help me with this build. I am an open book as far as concept design goes and the house is looking to be 1750 sqft or slab on grade with 2x6 walls and closed cell spray foam insulation if this helps. Thanks for any input ahead of time!
> 
> 
> Zack


Look into straw bail construction, do as much solar as possible, consider a co-gen system using waste heat to heat your house and water. With a large enough co-gen electric vehicles pay dividends.


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## brewerfan22 (Sep 19, 2014)

All I can say is wow. I am so incredibly impressed at the speedy and highly knowledgeable responses from everyone. I would love to answer all of the questions but I think some of the posters answered other response questions so I'll just stick to the main ones directed at me.

What do I have against basements? 
I am still very open to basements and have enjoyed basements in every one of my houses I have lived in, the only reason I was thinking of building without a basement is the added costs of having a basement poured and it being another area to need heat. As we all know heat rises and concrete does a pretty good job of staying cold here in Wisconsin winters I figured going without one would make heating the home more efficient. I could be way wrong and would love feedback on that if possible.

Propane vs Electricity?
Here in Wisconsin propane is usually a wash when compared to electric and I emphasize USUALLY. Last year we hit a 40 year low and they are saying this year is going to be no better. I have talked with lots of people who have LP tanks that run their house and they said last year an LP tank that would normally cost them 400 to fill jumped to 1100. Like @woodgeek stated I don't enjoy the idea of having a fossil fuel run heating system due to the fact its some other person that I have to pay and rely upon to heat my home. If it makes any difference the plan is to have the home on 40 acres and I would be willing to dedicate a few acres to having a tree nursery strictly for any wood burning appliance that would efficiently heat the home. I have always loved the smell of a wood burner I am just not aware of exactly how well thermo-regulation would be from something like that? Also another consideration I would have is if I am burning wood within the home is there any potential for ash, carbon or the like to be in the air as a pollutant in such an air tight house?

Passive House?
I have seen some other forums post about these and was very interested them there are only a couple of concerns I have. When you say that proper placement of windows and trees can almost heat the home by themselves what type of temperature are we talking? Like @jebatty stated above the winters up here can be -40 for weeks at a time with blistering winds. Also conversely our summers are also god awful at times where its 100+ with 97% humidity. While I'm no drama queen when it comes to temperature as last year we had our boiler in our current home go out and lived through the winter on just space heaters in that -40 weather, I would like to build this home with long term comfort and low maintenance in mind. Even if the house is 60-70 year round that would be perfect for me. I have heard about those heat removal ventilators that someone mentioned above but have yet to get a real clear cut answer on exactly what they do or how efficient they are to run, could someone elaborate?

Active Solar?
This was my original plan for the home. I wanted to either do active solar or a wind turbine or a combination and tie to the grid to reap the benefits of being able to make money on my investment while it powers my home as well. Like @woodgeek mentioned though they are actually going to start charging a fee to active solar users here in Wisconsin per month for being an active solar resident. Do I think the benefits of being self sufficient outweigh the added costs? To a certain degree yes, but Wisconsin also has its disadvantages when it comes to solar as well. Our average insolation is about 4.2 hours and I think if I remember correctly we can hit lows of 2.8 or 3.2 so having something else in place on those crummy days would be ideal. 

OWB for in slab heating?
This was my second ideal option for home heating but not in slab. I was thinking more along the lines of running radiators in the homes and using the OWB like a traditional hydronic boiler. My only concern with this is maintenance and longevity. I will be on well water and it will be iron/sulfur rich and I am not sure what this would do to a closed loop system of heating. I know that the lines that are run are pex and would not rust but over time the water would become more and more like sludge or that's how it makes sense in my head. Would someone care to take a stab at this as well?


Thank you all for your input this far it is helping immensely!

Zack


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## jebatty (Sep 19, 2014)

It may have been mentioned so forgive the repetition: for a tight house, plentiful fresh air year round and humidity removal during the heating season are very important. You need to plan for excellent HRV.


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## jebatty (Sep 19, 2014)

> OWB for in slab heating?


Makes me cringe.


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## woodgeek (Sep 19, 2014)

A couple ponts of clarification....

'Active solar' usually means solar thermal panels, not solar electricity, which is photovoltaic or 'PV'.  I think most of us are very positive on PV-grid tie, many members in here have PV systems, but you didn't say if you were open to it in your first post.  @jebatty was recommending PV AND active solar thermal panels to heat water, which would be stored in a large tank as a 'heat battery' to allow you to store that solar heat and release it in a controlled way as needed.  'Passive solar' is of course just sunlight coming in windows, and dumping heat into the space.

Sounds like you are interested in self-sufficiency, and wood heat with 40 acres is def a great way to go.  Insurers will usually require a non-wood heating system to be installed also, and that will be nice to have if you have to travel away from the house in winter.  Since you won't be running it much, for the backup system you care more about low up front cost than you do about fuel cost.  This brings you back to a cheap propane furnace with a tank of propane that gets refilled very rarely, or an electric baseboard system.  The first one is easier to integrate with central AC.

For wood heat questions you came to the right place.  Bottom line: a single wood stove is great for delivering a certain amount of heat, depending on the size 20,000 BTU/h to 40,000 BTU/h.  If your house is poorly insulated (like many existing houses) then you need a lot of heat, and you need to go through many cords of wood a season.  The result is not great...you are stacking, storing and hauling a LOT of wood, you need a huge stove or multiple stoves, and the far end of the house away from the stove can get cold....distributing all that heat is hard.  Conversely, if you are well insulated, your wood consumption and work gets reduced a lot, you can buy a smaller stove, you can reload/burn less often, and distributing the heat gets a lot easier so temps are a lot more even, even with a single heat source in one room.

**From a self-sufficiency POV, I would build a 'super-insulated' house with above code insulation and airsealing levels, the most cost-effective route being the PGH, pretty good house. The resulting house would use far less heat than any house you have ever been in (probably only 1/4 to a 1/3 as much), so you would have to adjust your thinking re heating bills and fuel consumption downward.  HRVs are still still expensive, the cheapest ones recover 50-60% of the heat from the air streams.  Ones that do 80-90% are available from European sources, but cost many thousands of $.   You will likely get one of the cheaper ones, which as I said, are standard in new houses in Canada.

**I still think you would get ducts inside the structure, and the smallest propane furnace and central AC unit they sell, and both would still be a bit too large.  You would get most of your heat from a simple wood stove, a point source of heat, and it would mostly circulate naturally due to an 'open plan' layout.  IF you wanted to boost the distribution, your furnace blower would help with that (get an ECM blower motor for efficiency).

**You would get your electricity from a PV grid tie arrangement, and would design the house with a good roof for solar...having one roof plane facing South or nearly so, and not making it too shallow of a pitch, and design out any penetrations (vents, chimneys, etc.) from that plane.  The steeper pitch will get you more power and better natural snow shedding.  Having the roof under your panels fail and leak is a real PITA, so, you might want to get a metal roof at least on that plane, rather than shingles, and the panels and roof could last together for decades.

Your plan is doable with current building science and technology, but many things that folks figured out decades ago will not apply.  While you will get some passive solar heat, you will not be building huge south facing windows and huge amounts of thermal mass....that approach is very tricky and seldom resulted in a comfortable house.  You will be super-insulated, and design a more normal looking amount of south-facing glass, with overhangs so the sun doesn't cook your house in the Summer.

This is obviously a wood-burning board, and this and the other rooms will tell you everything you want to know about wood heating.  In a super-insulated house a lot of the challenges of wood heat will fall away, and you will just be left with the many pleasures of it.

But for building a house, you need to read up about that somewhere else....I rec Green Building Advisor.  They have a huge amount of info and blogs about all the tradeoffs and options we have discussed above, and invented the PGH concept.  You will be unlikely to find a builder who knows this stuff...you will find conventional builders who will talk you out of any 'more than code insulation' options, or will happily upinsulate some areas of the house he can do easily, e.g. the attic, but not others, resulting in bad thermal performance.  IF you hunt around, you might find a passive house builder who can deliver you a 'passive house' that can be heated by your body heat, for an eye-popping construction cost.  You need to find someone who is experienced building energy efficient super-insulated houses, but who isn't seeing you as a bottomless pit of money.  You need to be knowledgable enough only to find the right person, so they don't sell you a bill of goods.  And that will be the hard part.


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## jebatty (Sep 19, 2014)

My lack of clarity. I considered solar PV as active solar. I was not recommending solar PV to heat water and I was not recommending solar thermal to heat water. I was recommending a wood gasification boiler to heat water and with substantial storage to allow long periods between required firings.

My recommendation was solar PV for electricity in a grid-tie installation. Solar PV and mini-splits can work very well during much of a winter in the northern US. In my area of MN, only January typically is the really cold period. Much of winter is in the +10F and higher temperatures. The low point of solar PV occurs in January, and even then solar PV is 63% of maximum solar PV, which occurs in July. While winter days are short, solar intensity (low humidity, low atmospheric dust) combined with low temperatures results in very high solar potential. And even at current prices, if more electricity is needed in winter, it makes sense to add panels to provide needed winter electricity, which also may fit well for higher summer demand due to air conditioning.


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## woodgeek (Sep 19, 2014)

I agree with everything Jim @jebatty is recommending solar-wise, and misunderstood his earlier post.   He has great experience with PV not far from you.  He also recommends 'minisplits' for heating....I like that approach for heating, but I had assumed would be a no-go in your climate.  I'm happy to be wrong.   You should look into them, they would provide cheap heat and AC.

I still think a wood boiler and storage is overkill for a super-insulated house.


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## jebatty (Sep 19, 2014)

> ... a wood boiler and storage is overkill for a super-insulated house.


This may be true. My gasification boiler/storage recommendation was influenced by that use to heat my shop, 1500 sq feet, in-floor heat (constant 61F). During a typical winter I burn wood with btu content of about 56 million. That's equivalent to,16,500 kwh of electricity. At my general electric rate of $0.108/kwh, that is $1,780 annually for heat. That's also about 725 gallons of propane in an 85% efficient heating appliance, and use whatever per gallon cost might be reasonable ($2/gal = $1,450). I also have my own wood supply and c/s/s all of my own wood. At truckload rates for logs, purchase of this wood is about $250, or if purchased c/s and delivered, about $600 in my area.

Depending upon applicable rates in the OP's area, gasification boiler/storage may not be reasonable.


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## maple1 (Sep 19, 2014)

Mini-splits + good wood stove, heat pump water heater for DHW.

Next?


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## semipro (Sep 19, 2014)

brewerfan22 said:


> I have always loved the smell of a wood burner I am just not aware of exactly how well thermo-regulation would be from something like that? Also another consideration I would have is if I am burning wood within the home is there any potential for ash, carbon or the like to be in the air as a pollutant in such an air tight house?


You might consider a masonry heater with a dedicated outside air source then.  This combined with a backup system, especially something like a mini-split would seem to be ideal for your.  You may even be able to incorporate some of the hydronic features you like into such a unit. though I've not seen it done.  That might also be overkill.
If you like the idea of  masonry heater now is the time to plan it in to your house.  They are big honking stacks of rock that need to be centrally located.


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## Dune (Sep 19, 2014)

OWB for in slab heating?
This was my second ideal option for home heating but not in slab. I was thinking more along the lines of running radiators in the homes and using the OWB like a traditional hydronic boiler. My only concern with this is maintenance and longevity. I will be on well water and it will be iron/sulfur rich and I am not sure what this would do to a closed loop system of heating. I know that the lines that are run are pex and would not rust but over time the water would become more and more like sludge or that's how it makes sense in my head. Would someone care to take a stab at this as well?

In slab pex if installed and used properly will use 1/3 less energy than radiators and is all around more comfortable. 
In a better than average home (such as a pretty good house) a decent water heater could run your floor heat, and having excess thermal mass is critical to a passive solar design. 

The ultimate therefore is a passive solar orientation and design, with in floor radiant tubes, solar hot water combined with  a wood boiler with massive storage and for backup heat electric baseboard (it is cheapest and you should seldom if ever need it). 

Oh, and I would set up your heat loops so you can drain and flush them every year and filter the inlet water.


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## moey (Sep 22, 2014)

Have you had a geothermal provider come out and quote? You probably could get by with close to the smallest system out there. With the tax credit it would cost about the same as a conventional system.


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## begreen (Sep 22, 2014)

Our geothermal quote was well over 2x the installed cost for air to air heat pump. Note that it also qualifies for a tax credit.


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## maple1 (Sep 23, 2014)

I spent a lot of money on my new boiler setup, but it would have been 2x that to go geo. Then I would have had seriously increased power bills for the rest of its life. So I decided to max out my time left on this earth by investing it in free fuel for as long as I'm able to do it. Then I can always switch fuels on the boiler if I just can't do wood any more. Or invest in the ever-increasing efficiencies of mini-splits or whatever else might be on the horizon.


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## moey (Sep 23, 2014)

Our geo system was about the same price as a conventional system. If I was to get A/C and a oil or propane system the cost for geo was nearly the same probably within 1-2k in the end. I quoted everything. I did have some wild quotes when I had companies come out though for geo. Some were 40% more then others. A lot seemed to depend on whether they were digging wells or trenches wells were significantly more. We have trenches.

The highest quote we had was 33k the lowest was 17k after tax breaks for a geo system. A new boiler install would have been 8-10k while A/C and ductwork would have been 6-8k. The decision was pretty obvious when I had companies come out and compared costs.


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## DickRussell (Sep 23, 2014)

As advised earlier in this thread, a new house in a place like Wisconsin really ought to be superinsulated, if only for the sake of comfort. Depending on what's envisioned in the way of size and shape, it can be shown in many cases that the relatively little extra cost to make it superinsulated, amortized over 20-30 years, is less than the savings in heating cost, so it could well be sound economic advice as well. But comfort alone is enough to tip the scale.

With a superinsulated house, a "geothermal" (ground source) heat pump (GSHP) can make a lot of sense, particularly if either the digging of trenches for ground loops is easy (cheap) or if a new well must be drilled anyway for domestic water supply and the quality of that water is good. While a heating system that burns a fuel doesn't come in progressively smaller sizes as the design load is reduced, a GSHP does. For a superinsulated house, that would be a quite small system. Your 1800 sqft of house is half the size of mine (around 3700 sqft net conditioned space, on two levels), in central NH (CZ 6). It's superinsulated, and it's heated by a two-ton GSHP. Last winter it kept the house warm while running in just first stage. For the electrical power it used, the heating season cost me less than $600. The extra cost for GSHP vs a propane system zoned the same way might well have been recouped by now, and I get cooling with humidity control all summer as well. For my situation, geo was a good fit. I suspect it would be a harder sell for a house of "ordinary" construction.

I do have a small woodstove in the lower level (Quadrafire 2100 Millenium; 11-28 KBTU/hr firing rate), mostly because I like watching a wood fire in the evening. But it does provide backup in the event of a prolonged power outage. We actually used it to heat the whole house in the 2010-11 winter when the crew was finishing the interior, before the GSHP was installed.

In my area, I had little hope of finding a builder with experience in building this sort of house. But I had done my homework over the years, knew what I wanted, down to small details, and designed the house accordingly. I found a local builder who liked "different," understood that this house would be quite different from anything he had built, and was eager to work with me to get me what I wanted. I particularly didn't want a builder who didn't want a homeowner telling him how to build a house, something he had been doing for the last 30 years. I didn't want a house built the way it was done 30 years ago. The arrangement worked out very well, and the house came out the way I wanted. Actual performance in bitterly cold weather has been slightly better than my heat loss model had predicted. If you are willing to invest a lot of time reading up on the subject, looking at sites like www.greenbuildingadvisor.com and www.buildingscience.com, you can specify your own exterior shell design and insist on the actual construction accomplishing that. But you have to be very involved throughout the project.


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## Deardorff (Oct 5, 2014)

Why not a corn burning stove? Ours burns corn, wheat, wood pellets and other stuff. This year we can get wheat for almost nothing - due to infections in the crop. Can't be fed to animals or people but burning poses no problems.

Corn/wood pellet stove backed by Propane and a few portable 'radiator style' plug in electric heaters do us well in Northern North Dakota. Our propane heaters work just fine when the power goes out - a major consideration during winter storms. Doesn't take long at 20-30 below zero for problems to surface when the electricity is off.


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## Hot-Tubes (Oct 9, 2014)

As the OP was trying to minimize grid use, what about incorporating a wood burning rocket mass stove as primary?  These are incredibly efficient and inexpensive to build.  Besides all the solid tips above, I'd also consider the core principle of a smaller home if it's an option.  That, an insulated slab, minimum of glass and maximum of passive solar features would make for a super efficient home.  I doubt you'd need even a cord of wood for a 1500SF new home built right.  

Bill Zelman
www.Hot-Tubes.com


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## chief72 (Oct 10, 2014)

Recently completed construction and test installation of of a rocket stove type heating system.....The rocket unit supplies hot combustion gas to the system while generating radiant/convective heat to the surrounds......Gas then exits rocket unit via a crossover tube and enters a secondary heat exchanger/heat bank before exhausting....Secondary exchanger is actually a rebuilt, resealed cast iron stove affording three effective passes for exiting combustion gas....Test burn results (averages) as follows: Top plate of rocket unit---695 deg. F avg., Rocket casing---578 deg. F avg., Crossover tube---525 deg. F avg., Cast iron stove shell---275 deg. F avg., Exhaust outlet---145 deg. F avg.

Unit incorporates a Tjernlund AD-1 draft inducer to assist with cold light-offs and to counter adverse wind (pressure gradients) conditions respective of the through-wall exhaust configuration.

Unit was designed to burn any quality/type of wood and will undergo exhaustive testing this winter to determine fuel consumption, thermal output and overall operational characteristics/flaws.....Theoretical maximum fuel consumption is 1/4 cord per season (6 months).....I've included a photo of the complete unit in its current test configuration.

Regards,
Chief72


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## woodgeek (Oct 10, 2014)

In the picture it looks like aluminized bubble wrap on the walls......isn't that combustible and very close to the radiant stove?


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## maple1 (Oct 10, 2014)

I don' t think you'd heat much of a space with 1/6 cu.ft. of wood per day.

Edit: there must be some condensation in the flue too?


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## chief72 (Oct 10, 2014)

Manufacturer's specs. rate that specific insulation for 180 deg. F max.......There is no fire rating given for it.....Before installation I subjected samples of it to some rather rigorous testing in the shop......A propane torch flame, directed at it from a distance of 6" only managed to melt it.....It took direct contact from the flame to initiate slow combustion of the plastic......Not to say this is the best stuff to use in a residential (or any) setting.....Stone, concrete or non-combustible backer board would definitely be more appropriate not to mention "code-worthy"....Bear in mind that the unit is currently being tested under shop/lab conditions by a qualified/trained engineer.....The test parameters require walls and ceiling to be covered with a material capable of reflecting radiant energy....To that end, the FBF insulation turned out to be the most cost effective expedient....To date, I've had no issues with insulation degradation during testing BUT time will tell.....BTW, that secondary HE is 12" from the insulation and runs at 225-275 F; a good litmus test for the FBF.......Future plans (if this system proofs out) are to encapsulate the unit inside a fireproof, insulated, reflective plenum chamber and duct the heat to the desired location(s).....All of that said; thanks for your safety concerns.

Regards,
chief72


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## chief72 (Oct 10, 2014)

maple1 said:


> I don' t think you'd heat much of a space with 1/6 cu.ft. of wood per day.
> 
> Edit: there must be some condensation in the flue too?


Theoretical fuel consumption is what the tests will prove or disprove.....To date, it appears as though the unit will operate (fire) on a 20% duty cycle......By that I mean that once up to operating temperature (about 20 minutes) it will be fired for a 15 minute interval then shut down for a 60 minute interval....15/75=.20.....The heat bank located in the rocket unit along with the secondary heat exchanger's mass will give up their stored heat during the "down-time".

Condensation is one of the issues that will be addressed during testing......So far, no condensation or precipitation has been noted anywhere in the system....Third stage combustion temperatures in the rocket generator are running about 1,800 deg F and appear to be generating 100% quality exhaust gas.


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## woodgeek (Oct 10, 2014)

Um.  Looks like the (single wall?) flue pipe is penetrating the wall adjacent to a combustible material (bubble wrap).   A chimney fire in that flue, and the plastic in contact with the flue will go up.  Whether that flame spreads to engulf the entire space will depend on the fine engineers at the reflectix corporation of america.

And, whats behind the bubble wrap....more combustibles?


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## BrotherBart (Oct 10, 2014)

Give it up woodgeek. Arguing with an engineer is messier than peeing into the wind.


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## jebatty (Oct 11, 2014)

Kudos to analyzing the feasibility of a rocket stove type heating system.

But if the stats are intended to represent something close to a final production stove, they just don't add up. 





> Exhaust outlet---145 deg. F avg. *** Unit was designed to burn any quality/type of wood ....Theoretical maximum fuel consumption is 1/4 cord per season (6 months)


 1/4 cord of oak at 20% MC has about 6 million btu's (or make it 8 million assumed for 145F stack temp compensation). That's 33-45,000 btu's/day over a 6 month period, or 1,400-1,900 btu/hr. And since the stove is designed for any quality/type of wood, for oak reduce that by about 50% for green wood, and if the wood is pine, reduce the dry/green btu's another 40%. That might be enough btu's to heat a single room in a cool/cold climate. Keep in mind that a 1500 watt electric heater (near 100% efficient) provides about 5100 btu/hr, about 3 times the maximum btu's the rocket stove is spec'd to provide. I don't know of anyone who can heat a house with a single 1500 watt electric heater, and the rocket stove design only provides maximum about 1/3 the btu's of the electric heater.

Next is stack temp - keeping in mind that the rocket stove is intended to burn any type/quality of wood.. The vaporized water from boiling off water in the wood (seasoned or green) and from combustion has to go somewhere, and that vaporized water at 145F going into any chimney in a cold environment is going to condense to liquid -- a matter of physics, not stove design.

So, interesting concept but at this point I would have to conclude not practical or feasible.


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## semipro (Oct 11, 2014)

Hang in there chief72.  Your system  has created an interesting discussion.  Its easy to pick on the work of others.  
I myself would be concerned about the use of what appears to be galvanized flue pipe where it might get hot enough to create the potential for zinc metal fume fever.  In general we're a safety-oriented bunch so you'll need to endure those criticisms first before the technical aspects can be discussed. 
You may want to start a new thread though to avoid hijacking of this one.


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## maple1 (Oct 11, 2014)

jebatty said:


> Kudos to analyzing the feasibility of a rocket stove type heating system.
> 
> But if the stats are intended to represent something close to a final production stove, they just don't add up.  1/4 cord of oak at 20% MC has about 6 million btu's (or make it 8 million assumed for 145F stack temp compensation). That's 33-45,000 btu's/day over a 6 month period, or 1,400-1,900 btu/hr. And since the stove is designed for any quality/type of wood, for oak reduce that by about 50% for green wood, and if the wood is pine, reduce the dry/green btu's another 40%. That might be enough btu's to heat a single room in a cool/cold climate. Keep in mind that a 1500 watt electric heater (near 100% efficient) provides about 5100 btu/hr, about 3 times the maximum btu's the rocket stove is spec'd to provide. I don't know of anyone who can heat a house with a single 1500 watt electric heater, and the rocket stove design only provides maximum about 1/3 the btu's of the electric heater.
> 
> ...


 
Hey, I already said all that - I just put a Coles Notes spin on it. 

Seriously, it's nice to see people trying to advance the science of wood burning, and I can appreciate that a test setup can be far from what some final version might look like (talking scale & safety things), and you might be on to something overall - but some of the things you stated just don't pass a first smell test. Such as, being able to efficiently burn any type of wood (and without condensing at the temps you posted?), and keeping anything beyond the size of a small room warm for 6 months of winter with 1/4 cord of wood. The BTUs just aren't there in that much wood - let alone wet or green wood.

Would like to follow progress though, and keep at it.


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## chief72 (Oct 11, 2014)

Absolutely outstanding.....Didn't expect such a volume of constructive input to my post this soon......Many thanks to all.

Let me address a few issues/concerns:

*Safety*: This project is being conducted in a controlled, industrial environment....The unit is actually set up in a test cell that was formally used to house my hydrogen heat treating furnace....The cell itself is constructed of 8" reinforced concrete (like a pillbox) and equipped with numerous safety/monitoring features designed to suppress fire, evacuate fumes and relieve excess pressure....Since this is a prototype project, there are still LOTS of variables to be explored; many of which could present serious safety issues....Definitely NOT a project for hobbyists.

*Unit construction*: Insofar as the unit is a prototype, a great proportion of the material utilized consists of short ends, drops and various components left over from other jobs....Semipro voiced concern about the use of galvanized, single wall duct pipe/fittings for high temperature application....The photo is somewhat deceptive in that respect....The duct pipe/fittings were actually fabricated from 30 gauge, T-316 stainless sheet....Having a completely equipped fabrication/machine shop at my disposal is very advantageous.

*Operating parameters*: Lots of input here from folks who have obviously been doing research in this area.....Several have commented on the unusually low exhaust temperature with regard to precipitation/condensation in the breaching duct.....The 145 deg. gas temp. occurs ONLY when the draft inducer is in operation....Once the unit attains operating temp. (15-20 minutes) the inducer is shut down, flow/pressure stabilizes and the system goes into natural draft mode.....At that point, the breaching temp. stabilizes at approx. 220 F.....The AD-1 inducer is designed for 5"-8" round ducting and is well over-capacity (at its lowest speed) for this system....In order to compensate for this, I installed a bypass system on the suction side of the inducer to lessen the effective air flow.
*
Fuel quality/consumption*: Everyone's arguments regarding fuel and its calorific content are consistent with facts/statistics/science.....I'll be the first to admit that I'm bucking the tide on this issue.....Hopefully, the design/construction of the rocket unit will get me close to that "1/4 cord goal"....The 20% duty cycle I mentioned is an absolute worst case scenario....Previous test firings indicated that the heat banks (primary and secondary) effectively retain/radiate for almost 3 hours once the fires are extinguished.....After 2 hours of downtime, the outer casing of the rocket unit registered 250 F in an ambient environment of 75 deg. F.....How this will all shake out remains to be seen....For testing, the heat will be force-ducted from the test cell (10' X 15' plenum chamber) into my 750 SF office area which is moderately insulated....I plan to have Bermuda shorts as well as my woolies and a parka handy during the testing phase just to cover all the bases.

Best regards to all,
chief72


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## semipro (Oct 11, 2014)

chief72 said:


> Semipro voiced concern about the use of galvanized, single wall duct pipe/fittings for high temperature application....The photo is somewhat deceptive in that respect....The duct pipe/fittings were actually fabricated from 30 gauge, T-316 stainless sheet....Having a completely equipped fabrication/machine shop at my disposal is very advantageous.


Great -- just what I needed, another poster here who's fabrications skills and facilities I can drool over. 
Seriously though, I'm impressed and love it when this type of stuff is posted.


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## chief72 (Oct 11, 2014)

semipro said:


> Great -- just what I needed, another poster here who's fabrications skills and facilities I can drool over.
> Seriously though, I'm impressed and love it when this type of stuff is posted.[/quot`


LOL, Semipro.....I spent almost 50 years learning the trade disciplines and building up my shop/business.....Still learning more with each passing day.....A few years ago I closed the doors but retained the shop and most of my equipment.....Retirement has allowed me to work behind closed doors without the day-to-day concerns associated with management, help and clientele.....Now I can concentrate my efforts on a few projects that I feel are intrinsically worthwhile....If this heater project bears fruit, I plan to make the design available in the public domain......That way, anyone may feel free to build their own or to improve upon my original design.....To do other at my stage of the game (IMO) would constitute wanton negligence and greed.


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## ihookem (Oct 11, 2014)

Not that I care, but you will miss the basement. It is cheap space per sq. ft. It cost very little to heat a basement. I live 20 mi. south of Fon Du Lac so I am a bit less cold than the poster. I do live in open farm country and it is not so much the temps as it is the wind. I have a 12 course basement (8') basement walls and 9' walls on a 2200 sq.ft ranch house so I am not much bigger than your house plans. I went with 2x6" walls with 4-5" of closed cell foam. I went with 2" foam on the outside basement walls, then I studded the inside of the basement with R11 fiberglass. That actually helped very little. I had foam sprayed between the floor joists (3") . Then I had sprayed the space shut between the roof trusses and up the roof sheathing about 4'. I went with 8" energy heel trusses. This is important cause it does away with ice daming. I then went with R60 in the attic.  I used Anderson 400 windows? and most were double hung with storms on them. The patio door has a storm that is made from another patio door so I have a thermal pane patio and a thermal pane storm . It is new this year but sure I will notice the difference on a windy day. . Honeslty, The windows use  a lot of heat. On a windy night it feels a bit cold and slightly drafty cause the wind blows so hard here by the wind mills. On a calm night -5 and even -10F is a very comfy home.  I have an east facing home so sun does not do a whole lot of good. Many say build the house to face the south side with windows. I can't put my house sidways on my 4 acres. I went with an EKO 25 gassifier and have 1000' of 1/2" pex. It is staple up under the floor in the basement. It is very comfortable heat like Jebatty mentioned. The pex is under the kitchen floor (hardwood floor) ,, and under the family room floor ( carpet) , under the front door area ( tile) and some in the master bath ( tile).  This woodboiler runs constantly at 160-165 degree temps. I used 4.5 cords of wood to heat and  the hot water. 1 full cord was popple and basswood so if it was all good hardwood I most likely would have used 4 cords. In the 2011-2012 winter I used 3.5 cords.  The temps in the house stays at at 68-71 dgrees depending on the wind, temps and sunlight.


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## Clyde S. Dale (Oct 16, 2014)

I'm jumping in late here and skipped a lot of the posts but wanted to share my experience with home construction. We built our home 8 years ago and acted as our own GCs because we could not find a local builder or contractor that would build a custom home for us exactly to our specs and material requirements. My wife and I are meticulous researchers and both had project management experience so we went for it. Like you we wanted to build as energy efficiently as possible and focused on the construction materials to achieve this.

For our exterior walls we went with Insulated Concrete Forms (ICFs). The company we used is TF Systems and they are right here in your state. There are many other ICF companies out there. We chose this one specifically because the sales rep worked with us on site from start to finish of both the basement and 1st floor walls. That included pouring the concrete for us. He charged us an hourly rate, but it was reasonable and well worth the experience and equipment he brought to the table. We ran the numbers for both conventional stick framing and ICF construction and IIRC it was about 10% more expensive to build with ICFs. 8 years later I would not have done it differently. Combined with energy efficient windows and Icynene insulation in our roof, we have the quietest and most EE house around. Our primary heat source is forced hot air (propane) but the cost of heating was signifcantly offset once we installed a wood burning insert.

It may be difficult to find a contractor that will work with ICFs. I can speak from first hand experience that they are not at all difficult to install. Anyone with construction experience should be able to do it. As I mentioned, the sales rep acted as the GC while during the ICF installation. We hired local Amish carpenters to assist with the process and they picked it up on the first day. It took 1 week to install/pour our basement and another week for the first floor. Once they are up, you don't have to worry about sheathing, insulation or vapor barrier steps with the exception of anything below grade. Below grade does require waterproofing and there are more options on the market now than we had at the time. We used a membrane called Platon and it seems to be doing the job fine. I'm sure proper grading plays mostly into this, but we've never had a single leak in our basement. Your house will be so tight that it will require mechanical ventilation. We have an air exchanger (ERV) that runs every six hours. 
Feel free to PM me if you have any questions - short summary: build your house with ICFs!


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## ihookem (Oct 18, 2014)

Clyde, What is your heat load on your house?


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## Clyde S. Dale (Oct 19, 2014)

ihookem said:


> Clyde, What is your heat load on your house?



I'm not sure and had to google the term "heat load". I can give it try if someone can give me the cliff notes on how to calculate it. Glad to do it if you are serious about ICFs.


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## peakbagger (Oct 19, 2014)

One suggestion on ICFs , if you have carpenter ants in your area you may want to consider that they love to nest and tunnel in foam.


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## ihookem (Oct 19, 2014)

Not interested in them but wonder what it would do to reduce your heat load. Heat load is a term used at how many BTU's per hr. ya use at -10F .


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## jharkin (Oct 20, 2014)

chief72 said:


> *Fuel quality/consumption*: Everyone's arguments regarding fuel and its calorific content are consistent with facts/statistics/science.....I'll be the first to admit that I'm bucking the tide on this issue.....Hopefully, the design/construction of the rocket unit will get me close to that "1/4 cord goal"....The 20% duty cycle I mentioned is an absolute worst case scenario....Previous test firings indicated that the heat banks (primary and secondary) effectively retain/radiate for almost 3 hours once the fires are extinguished.....After 2 hours of downtime, the outer casing of the rocket unit registered 250 F in an ambient environment of 75 deg. F.....How this will all shake out remains to be seen....For testing, the heat will be force-ducted from the test cell (10' X 15' plenum chamber) into my 750 SF office area which is moderately insulated....I plan to have Bermuda shorts as well as my woolies and a parka handy during the testing phase just to cover all the bases.
> 
> Best regards to all,
> chief72



I think you might be missing jebatty's point.  No matter how long the metal of the stove feels "hot" after the burn, at 1/4 cord over 6 months his calculated 1400 btu/hr is all he heat you are delivering to the room.  I know SC is a very mild climate but even there I dont think 1400 BTU is going to come anywhere close to enough for 750ft2.  That about as much heat as your typical home theater setup or powerful desktop PC throws off!


The laws of physics still apply, this thing cannot deliver any more heat to the room than what is liberated from the wood fuel burned, and a quarter cord is_ very _little fuel.


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## WiscWoody (Nov 2, 2014)

As far as building up here in Beersville Wisconsin, AKA Winter Wisconsin...I with regrets built a big high home doing much of the work myself and its not bad as far as cost to heat and power it. My electric runs $550 a year and i use 350 gallons of LP plus three cord of scrounge wood a year. It has poured ICF walls in the walkout cellar and R19 in the 6 inch standard walls above. I put R60 in the attic and sealed all of the leaks. I don't claim that it goes down to -30 and stays there for weeks but it does get that cold at night if not colder and itll warm up to 0 often during the day. WooHOO! theres ice on the lake now with the last couple of nights in the teens for lows. Ya got to love it I guess!!


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## briansol (Nov 4, 2014)

3 pages in and no one really has addressed the DHW use.  8 kids = 10 hot showers.   if even half of them are female, that's a LOT of hot water being used up.   A geothermal hybrid water heater will NEVER cut it.  person 3 is cold  let alone, 4, 5,6,7,8,9,and 10.

I think you're going to want a wood-fired boiler system if not only for the hot water set up.


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## Highbeam (Nov 4, 2014)

briansol said:


> 3 pages in and no one really has addressed the DHW use.  8 kids = 10 hot showers.   if even half of them are female, that's a LOT of hot water being used up.   A geothermal hybrid water heater will NEVER cut it.  person 3 is cold  let alone, 4, 5,6,7,8,9,and 10.
> 
> I think you're going to want a wood-fired boiler system if not only for the hot water set up.


 
Nah, just run a bath and wash all 10 of you in the same water. Father first is traditional.

My showerhead puts out 1.5 gpm of heated water. If we conservatively assume 10 minute showers and that the water is 100% hot water then you need 150 gallons of storage. Let's be smart though and assume that at least half of the residents shower in the morning vs. at night so 75 gallons is fine. Totally in the realm of available water heaters.


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## johnny1720 (Nov 4, 2014)

I have a tankless propane hot water heater, we only have 2 kids and me and the wife.  This thing uses about 160 gallons per year.  If you need that much water go with a tankless.


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## woodgeek (Nov 4, 2014)

My oldest daughter has occasionally taken 90 minute showers,   with a 1.5 gpm showerhead not going full blast....didn't run out of water with my (80 gallon) HPWH on 'eco'.


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## Highbeam (Nov 4, 2014)

woodgeek said:


> My oldest daughter has occasionally taken 90 minute showers,   with a 1.5 gpm showerhead not going full blast....didn't run out of water with my (80 gallon) HPWH on 'eco'.


 
I would freak out! More worried about my 51 year old septic system than anything.


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## semipro (Nov 5, 2014)

woodgeek said:


> My oldest daughter has occasionally taken 90 minute showers,  with a 1.5 gpm showerhead not going full blast.


In my experience if you close the HWH supply valve slowly enough while they're showering they'll think they've used up all the hot water.  

Edit: there is this also: http://www.showermanager.com/conservation-store/shower-timer-home.shtml


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## woodgeek (Nov 5, 2014)

Eh, works out to ~$0.60 of wind power.  Its not like it happens every day.  

I prefer the low tech solution of banging on the door loudly after 60 minutes.


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## jebatty (Nov 6, 2014)

You can reduce you hot water costs dramatically by getting a sand box and rolling around in it occasionally to rub the dirt off, also no need to use pumice or the like to get the dead skin off, defoliate on the cheap. Energy for hot water used = 0.


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