I've been reading this site for years and I am finally getting closer to being able to build my dream home. The problem I'm having is that I've read so much it has gotten to the point where I feel like I don't know anything! I'm not normally the ask for help type, so this post might be a bit all over the place, just warning in advance. My main two questions are the best way to heat it and the best way to insulate it.

My Location is near the Wisconsin/UP MI border (54847 is the closest "big town" zip) so I'm in a heating dominated climate. I currently live in a house with practically no insulation and a small window AC is more than adequate for cooling. It is only used a few days a year so I would think that I could get away without any air conditioning.

My goal is to build a house where I feel that I've spent my money in the most intelligent way possible. I will have a crew frame up the house and set the windows, but I will be doing the rest of it and time doesn't mean much to me from a cost standpoint. I would actually say that I'm looking forward to spending time on the project. I'm one of those weirdos who would rather pay to work than to sit idle. Also, I have access to an insulation blower for dense packing and have done so with success on other projects in the past.

The house will have a 1200 sq ft footprint with a full basement and full second story. The basement will not be used as living space, but will be used as a hobby space. Basically, I'm fine with the temp not being any higher than 50-60 down there. The upstairs will be the master bedroom and bath, so ideally it will be cooler than the first floor of the house. The main floor will have an open floorplan. I will have 156 sq ft of South facing windows on the main floor and 125 sq ft of south facing windows on the second floor. There will also be 60 sq ft of north facing windows on the second floor, but they are in auxillary rooms (laundry/closet/stairway) and can be plugged for the winters (assuming there isn't a problem doing so). The windows will be double pane with automated insulated blinds. The house is in the woods on a hill with a lot of old red pines. Basically, very little direct sunlight in the summer, a small amount during the winters.

Insulation: I would like to get to at least R40 walls. This is the area that the more I read the less I feel like I know. In a perfect world I'd do a 2' double wall and dense pack it with cellulose, but in my experience I've found that the machine I use doesn't get the right density on a uniform basis when doing anything bigger than a 24"x 5.5"x 120" area so that rules that out. At this point I'm considering 3 options.

Option #1 is to do a 2x6 load bearing wall for the exterior of the house. Dense pack that then put 4" of iso/eps followed by a 2x4 wall which will also be dense packed and then drywalled. Is something like this practical? I've never read of anyone doing it this way and I'm sure there is a reason for it, I just don't know what the reason would be. The pros to this would be that the framing would be inexpensive, I could put a stone veneer on part of the house (I'm not comfortable with stone over 4" of foam), high R value, I could do most of the work myself. The only con I can think of is that there would be a lot of messing around to get the details of the rim joists right. I'm sure there are other cons and that is the reason I haven't read about someone doing it like this, I just don't know what they are, but I'd guess it has something to do with a vapor barrier being in the middle of a wall assembly.

Option #2 would be a double wall system with a 2" airgap and strips of foam between the interior and exterior studs to make the bays narrow enough to get a good dense pack. I would have 1 or 2 inches of CCSF sprayed before I dense packed to get a good seal. The pros and cons here seem similar to option 1 but there would also be the added cost of the spray foam which I'm not crazy about.

Option #3 would be a regular 2x6 wall with 4" exterior foam. I like the way these systems perform (based on reading, haven't actually seen anyone do that around here), but the window detailing scares me a bit. I only have a total of 9 windows in the house, but the smallest are 5' wide and the biggest are 10' wide. I plan on putting a 42" high stone veneer wrap on part of the house (about 35 lineal ft) and I don't like the idea of putting it over foam. I know it can be done, I'm just not comfortable with it. The other con is that I'm not using as much cellulose and that's the biggest bang for the buck in my situaion.

My questions are:
- Does option #1 work or will it lead to problems? That seems to be the best bang for the buck if I can make it work.
- Are any of these options the smartest way to go about it when you consider framing/window hanging costs are the biggest out of pocket expenses I will have (CCSF would also be a high cost deal for me)?

Heating Obviously I don't know what my final R values will be, but using R40 walls, R60 ceiling, R10 basement and basment floor insulation in a tight home, my heat loss calcs put me around 30-40kbtu on a design day. I would love to just put in a couple of hyper heat split units in and heat the house that way but it gets really cold up here and natural gas is cheap so I have to take that into consideration as well. One thing I absolutely hate is duct work running all over a house so I would like to avoid it if possible. Having said that, a natural gas furnace is a cheap way to get heat around here. I was wondering if it's possible to have one huge duct on the first floor. I've read a lot of theories on superinsulated houses being isothermal, but I've never come across any hard data that led me to believe it's a great idea. Another option I have is to pour gypcrete/concrete on the first floor and go with in floor heating. I've put in floor systems in other projects so I'm comfortable doing the work, but I'm afraid the added costs of beefing up the floors and all that concrete works against my goal of spending money in the most intelligent way possible. I suppose an underfloor/stapled up type of radiant system is an option too. I haven't done one of these but there is a first time for everything.

I will also have a 60 sq ft, 3" thick concrete island in the kitchen that I plan to run tubes through and hook to the wood boiler (huge) that I will be heating my garage and shop with. I also will have a 20 sq ft slab at the opposite end of the open area that will have tubes in it. I have a couple hundred square feet of wall that will have stone veneer on it and have thought about running tubing in the walls in those spots, but I am not sure how much I like the idea of water lines running in walls. I plan to use the radiant heat at all heating times and supplement with whatever else I put in.

My questions are: -Can point source heating work in a 3 story plan with a 1200 sq ft footprint considering that I'm fine with the upstairs and basement levels being cooler (even significantly) than the main level? I'd say I could supplement the main source of heat with electric baseboards, but the wife will have none of that so they are out.
- In a cold climate like I'm in with cheap natural gas, does anything other than a furnace make sense as a primary heating source? I'd love to just use the wood boiler for everything since I have the wood and I'm filling it for the shop anyway, but around here we need another source by code.
-Is an exhaust only ventillation system asking for trouble? We have a lot of days where you almost have to open the windows because the weather is so perfect, but winter does get long. I'm fine with opening windows occasionally, but there will be weeks where it's just too cold to be doing that.

Sorry for the rambling nature of my post, guess that's what happens when you wait 6 years to ask your first question!

I'm unclear if #1 & 2 are similar double walls, but I would recommend that the foam insulation between the double wall be solid and not intermittent strips, and that it be permeable - so use eps rather than iso. Otherwise it looks good. If you use ZIP sheathing or some other method to seal the exterior walls so they are airtight you could eliminate the spray foam. If you decide to use it, place it on the inside of the exterior surface and not on the inner wall. The wall needs to be able to breath to the interior.

You did not mention your basement insulation, but since that is an integral part of the envelope, it does have to be completely sealed and insulated, and the concrete floor thermally isolated from ground and any cold concrete. Built like this, a point source unit should work fine. Lots of builders are using minisplits so you may want to consider these.

A heat exchanger would be a better way to go than exhaust only. In either case you'll need replacement air to make up for the air that is exhausted - with an exhaust only you're relying on cold air seeping in under the doors; with an HRV or ERV you're bringing in conditioned - warmer - air.

Keep in mind that the tighter the house is, the easier it will be to heat and the longer it will "coast" before the heat comes back on. But a very tight house can be problematic with burning fuels, so any furnace or boiler needs to be air tight and use outdoor air for combustion, not "room" air.

Point source heating with R40+ walls works, but it works better if the rooms doored-off from the source have very low heating loads (==limited window area). Temperature balance can be improved with ducted HRV/ERV ventilation systems by putting only source-ventilation near the heat source, and only exhaust ventilation in the doored off areas (pressure-balanced with jump-ducts or transfer grilles, door cuts, etc.)

The air-gap in #2 is a thermal bypass unless you're filling it with spray foam. Closed cell spray foam would have more lifecycle greenhouse gas potential than the energy use it's offsetting in a stackup that thick. EPS or iso doesnt' have that issue, but the blowing agents for XPS is even worse than those for closed cell polyurethane. It's better to use cc foam for air seal & moisture control rather than for bulking up the R.

I don't see how you're coming up with anything LIKE 30-40kbtu/hr heat load on a 2400' house with R40 walls and R60 roof, sitting on top of a semi-conditioned R10 foundation (which should be R20 foundation walls, R10 slab, if you're trying to spend the money reasonably).

With better windows and possibly some trimming of glazed area more likely to come in under 25KBTU/hr at the 99% outside design condition even in da-yoop (and I'm assuming you're in WI, not the-UP.) Looking at the weather history for 54847 it looks like your design temp will be between -10F and -15F, which could be a bit of a stretch for heating with mini-splits during the coldest hours of the coldest days, but it's not out of the question. The Mitsubishi H2i series put out over 70% of nominal heat rating at -25C/-13F, so maybe. A 2-head (one head per floor works for point source on multi-storys) 2.5 ton Mitsubishi multi-split would be capable of putting out ~25K at -13F, and with a wood-stove/boiler or electric baseboard backup there would always be at least part of the house toasty warm even on the rare days when it hits -25F.

Check your real weather history see: weatherspark.com/ (plug in your zip code or city, even if it's a tiny zip code if there's a weather station it'll have a history in the database)

Heating with gas would be cheaper (hydronic loops with baseboard or low-temp panels off a condensing tank-type hot water heater would be pretty cheap to implement) than with mini-splits, at least during the coldest weather, but it depends on your gas and electricity rates- it varies a lot. If you're in 5-cent electricity land mini-splits may be the right solution even if gas is under a buck a therm. But if you're already running radiant floor with the wood boiler it's not worth paying extra for.

Option 3, a 2x6 wall with 4" of exterior iso would come in around R35, derating the iso for your design temps. You could boost that to between R45-50 with lateral 2x4s and cellulose on the interior "Mooney Wall" style, without the complicating feature of double-wall construction that you have in option #1. Bump the attic R to 75 too, since that's a relatively cheap upgrade. Doing the basement as an R20 or R22 insulated concrete form (ICF) and aligning the exterior foam of the ICF with the exterior foam of the above grade wall simplifies thermally breaking the band joist and foundation sill, which is something of a lower-R point. It also makes it easier to get good air tightness there, but it's still worth putting an inch or two of closed cell foam on the interior as an air seal.

Thanks for your reply Bob. Am I understanding you right in that if my wall stack from outside in were to go Zip sheating >> 2x6 load bearing wall dense packed with cellulose >> 4" EPS foam >> 2x4 non load bearing wall dense packed with cellulose I would be alright? That would be my ideal option if it works.

I haven't completely decided on my basement yet. It will certainly be insulated and sealed, I'm just not sure which route I will go. I'm trying to decide if the ICF route is something I feel comfortable tackling or not. The floor plan is a rectangle, so not very complicated, but it is another thing that isn't done much around here so all my knowledge is virtual. It will be insulated, sealed, and thermally isolated no matter which route I go though.

I figured that a HRV would be the route I would have to go, but I thought I might as well ask about it since I have read that exhaust only works in theory.

You were right Dana. In my nervousness about making my first post I looked at the spreadsheet for the wrong plan. My numbers on this plan were in the 20-28kbtu range.

Thanks for the link to weatherspark. I don't know how I've missed that in the past. What a cool site!

I would think that wall would work very well - that is about R48, depending on exactly how it's computed, but certainly a high enough R value.
I missed seeing your basement R values earlier, but IMO the wall values should be close to the upper wall values and the floor should be R-20. It's up to you whether to use ICFs or not; I've been using 2" of foam and 5-1/2" of cellulose or fiberglass which is about R35, on the interior of a standard concrete wall. Not too expensive but it works well. You'll find lots of opinions about the amount of insulation under slab, but its pretty expensive to upgrade that later on.

Subsoil temps in that area are on the cool side, but not permafrost. :-) Still if the slab is going to be heated even part-time with either the wood boiler/other R10 would be the minimum sub-slab insulation, and R20 wouldn't be insane.

Some of the Building Science folks and others take the "pretty-good house" shorthand of 10/20/40/60 for slab/foundation/above-grade wall/attic for a house that has at least SOME economic rationale for climate zone 6. But there are particulars of $/R expense, window area, radiant heating, etc where you'd want to deviate from that. Sub slab R runs about 10 cents/R/square foot if you use EPS, a bit more if you use XPS, and a lot LESS if you use reclaimed EPS from commercial roofing demolition (not recommended for slabs bearing any portion of the weight of the house, but OK under a 3-4" residential slab if not prohibited by pesky building codes.) Cellulose is cheaper per unit R than most options, but if there's even a 1% chance that you'd get bulk water in the basement at some point in the next 100 years you'd probably want to use something else in the basement.

I'm a big fan of using reclaimed roofing iso in place of fiber, even in basements, and it's usually cheaper per unit R than batts. On a recent deep energy retrofit project I've been advising on (in climate zone 5) there was 6" of reclaimed iso above the structural roof deck with 5-6" of closed cell foam between the rafters (over R55 whole-assembly on average), 4" of reclaimed iso outside the antique plank sheathing with 1" of foil faced virgin stock over that on the exterior (seams staggered & sealed on both layers), and cellulose in the full-dimension 2x 4 studs, which came in at around R40. The material cost on that was under 3 cents/R/foot, saving several thousands on the budget. If you have a design that can take a truckload of it, insulationdepot.com will deliver, if you can't find local sources. (In my area there are multiple sources dealing in reclaimed rigid foam.)

The basement common area of this 3-story 3-family house was unheated but housed the water heaters & laundry, with R10 XPS under the slab, and R12-14 in closed cell spray foam on the walls. The basement ceiling and the ceilings between floors got ~ R40 low-density cellulose treatment, more for sound abatement and potential thermal bypass air retardency than for it's direct R-value. Each floor/unit has an identical 1.5 ton single head mini-split for both heating & cooling. Manual-J heat load was under 15K for the lossiest unit, a bit more than 11K, but the few west facing windows brought the cooling loads up a bit, and 1.5 tons was a reasonable fit for any of them.

To improve temperature balance, the bedrooms all had less than 12 square feet of U0.20 window, and only exhaust ducts for the ERVs, with jump ducts from the common area supplying ventilation air to those rooms. The open living/dining areas got 100% of the ventilation supply. We'll see this winter how well that works at the 99% outside design temp, but similarly heated & ventilated single-family home use that scheme successfully. Window size & performance on the doored-off rooms are an important design consideration when taking point-source heating approach on a high-R house, since that's what dominates the heat loss in those rooms.

We design HVAC systems for dream homes like yours every day. With modest homes or loads determined by a proper Manual 'J', we start with a condensing water heater and a weather sensitive controlled sub-system to drive your radiant floors. If you want to use a wood boiler, we can integrate the two for automatic back-up. We also us electric boilers for back-up occasionally, if the wood is going to be used most of the time or the electricity is cheap, not so much near the UP. All the new houses we design end up with sealed combustion appliances and a HRV or ERV for bath exhaust.