Hello,
    I am set to build a home in Southern Ontario in the next month or 2 and I am in the final stages of the planning. I have been researching and planning this for over a year and have a lot of contradicting advice. In my local area it seems that I do not have many people to lean on for advice in building a super efficient home.
    I have found one builder who builds air tight homes and has homes with the similar design of mine to rate 85+ in the energy star testing and blow door testing. He usually build a home with 2x6 walls filled with celuose with 1.5" exterior foam claiming to be a R34 wall. I know with thermal bridging this will not be the case, but it is better than most builders in this area.
    We have been talking and might settle on thermapan SIPs as they can provide a 8.25" wall at R38, but there is a connecting stud every 4' so I will lose effectiveness due to thermal bridging. They can provide a 10.25" wall for an R49 value at an additional $1700 (for entire home), but thermapan tells me the ROI is not there and with the additional cost due to the wider walls it is not worth it. My original thought was another r11 for $1700 was worth it. What are peoples thoughts on this? Maybe should I do some type of exterior foam to stop the thermal bridging? Is money better spent on the exterior foam or the 10.25" wall? The walls will be 9' high walls also.
    The basement will also be 9' high walls with 5.5" underground while the rest will be above ground (I am near a river and have a windows in bedrooms so elevation of window openings plays a factor). This will be a nudra ICF foundation with an R22 wall. The basement slab will be insulated with old door panels giving me an R10 underslab insulation with seems and such taped.
    My windows will be a fiberglass window from Fibretec (doors also) triple pane giving me a U value of 0.15.
    The home will be cathedral ceiling throughout the home at a 8/12 slope with a 12/12 exterior roof slope (I know cathedral is not the best for insulation). My builder tells me we can spray celluose in the ceiling and get a R65 value. I will not be doing any recessed lighting in the ceiling only fixtures (prob track lighting and such, any input on lighting would be amippreciated).
    The home is a rectangle home 62'x32' so just under 2000 sqft on the main level. The front door is facing South and the East side of the home is a rectangle 16'x32' which will be the master bedroom and onsuite. The rest of the main level is an open concept style with the living room, kitchen, dinning, office and then a small laundry and powder room.
    We have a 34'x32' attached garage with a loft above that will sit on a beam and give me a large living area for the kids.
    I plan on using the basement in the future as a game room and entertaining area.
   
    Besides the few questions above about the exterior insulation (maybe people have input on the ceiling and underslab?) I am trying to figure out my heating system. I would like to stay away from a ducted system because of efficiency, air quality and also head room in the basement and the difficulty of running the system into the loft. I am hoping I could run a main system based on mini-splits only. I have done some research and it seems people are doing it, and there is evidence in Quebec. I have spoken the a few local heating and cooling contractors and they do not seem knowledgable on different systems at all. I have connected with who I was told was the best heating and cooling guy in the area and he is telling me that:
    1- the mini split would not be efficient in the low temps and would not heat the home nor be efficient
    2- I would have other room that would be very cold
    3- I would need a commercial grade system 36,000 btu that would be very expensive

I have done a lot of research and have read of people building homes similar to mine in similar environments and heated only on mini-split systems. From my research I would be able to put a main unit in my wide open area to heat the main floor (46'x32') and then use a separate mini-split for the loft. From my research the bedroom area would be sufficiently heated and cooled from the main area, but I may have to provide ventilation or leave the doors open. I would think I would still probably want a small unit for the master area regardless. From my research it seems to be more efficient to run separate systems and stay away from multi head units. I was hoping I could have 2 small units (loft, master area), then 2 larger units (basement/main floor).

I have used hot2000 to do my own heat loss calculations and using a total value of R33 for the walls (estimated down the R38 for thermal bridging) it calculates 18,000 btu of heating needed in the home (entire home basement and loft included). Are my calculations wrong? Is over sizing the mini-split ok or does my efficiency drop down?

Thanks for any and all insight, I have been learning a lot throughout my research but as with many things there are grey areas and not everything is black and white. Any input on anything in the home is always appreciated as I am trying to build the best home reasonably possible as I plan on living in the home for the next 30 years. Currently it will be in the middle of an open field, but I have planted over 1000 trees around the perimeter to provide a wind break in 10 years.

   

This is my attached approx sqft the windows will cover in the home also (this number will drop a bit as I do final revisions):

South 163.777673
North 187.1387691
Basement N 23.99998464
East 32.99997888
Loft S 26.6666496
Loft W 29.9999808

If you are in deep southern Ontario, most seem to agree that minis will work. Myself, I'm not completely convinced that you won't get cold areas but your fall back position would be a few cheap resistance (baseboard or other) heaters. If there is a month that you need to run some additional heat, it should be more then offset by the savings of installing and operating the minis compare to a full blown system. You would still need to do make up air, so add in the cost of an HRV when comparing.

Your calc's might be a bit low but not by much.

Doing electric resistance under tile floors in a small area is a nice way to get some luxury. It puts the heat in a very specific area and also contributes to the overall heating picture. An ideal place is in a bathroom shared by two bedrooms, particularly if you are worried about the bedrooms being too cold.

I'm doing a 2700 sf house on 2 levels; but I'm in California. The only part of your decision process that changes is how low ddo your temps get, and what is the efficiency of the mini-split at that temp. 1) Do a manual J calc; sounds like you did. You can also use BeOpt as well. 2) get the BTU/hr for the house; great, you have that. 3) Design the size and placement of minisplits to optimize heat transfer; done 4) My house is not as efficient as yours; 28000 BTU coldest temp. I got 2 minis; 1 of which has 2 heads; installed cost is 11,000 USD for 36000 BTU 5) If back up is desired for coldest nights, consider cove heaters. Remember, a bedroom probably has a very low BTU need, less than a mini is designed for. 6) Shop around for HVAC guys who are in the 21st century. I had to go through 7 quotes and twice that many inquiries, but the actual labor is only a couple of man-days, way less than ducted HVAC.

First, round off your window sf rather than go to 7 decimal places. Makes reading it easier & doen't make that much difference.
Second, if the energy star values are the same as ours, 85 isn't that good; like getting 24mpg rather than 21.
Third, your ideas are sound - you can easily heat with minisplits IF the house is superinsulated and airtight. If it gets below -15 regularly and for extended periods, you may need supplemental heat. Electric baseboards or small wall units may work fine.
Forth, the easiest and least expensive way to get high R values (R-40 walls) is double stud walls with blown in cellulose, or blown fiberglass or Roxul batts. Airtightness is achievable if you pay attention. SIPS and spray foam are good products but they are not necessary for a well insulated house.
Fifth: airtightness is as important as R value. A leaky house with R50 walls will not work well.

Thanks for the insight everyone and confirmation on some of my ideas.
Does anyone have any recommendations on the best way to insulation the cathedral ceiling and having the air tightness? Should I be looking for 1-2" of spray foam then fill with celluose in a vented type configuration?
Any other ideas for backup heat on the coldest days of the year? Electric baseboards are ugly and I have very small children.

The Mitsubishi M-series single head mini-splits (MSZ-FH12NA or -15NA or -FH09NA)) have significant capacity and run at a COP of about 2.0 @ -25C outdoor temps, and would average over 3 for the season in most southern Ontario locations. The Fujitsu -XLTH series (AOU-15RLS2-H , -12RLS2H, or -9RLS2-H ) are nearly that efficient, and have a rated capacity at -15F/-26C.

The 1.25 ton units in either of those series deliver about 15-16,000 BTU/hr @ -25C. The 3/4 tonners deliver about 8-10,000BTU/hr @ -25C. You can definitely get there from here when your whole-house design heat load is under 30,000BTU/hr. What is your outside design temp? (Or the nearest city, so we can look it up.)

Radiant cove heaters mounted up at the crown-molding level above windows (sized at no more than 2x the design heat load for the room) is a far superior auxiliary heating solution for the doored off areas or cold rooms than electric baseboard, for both comfort (it raises the average radiant temperature of the room, lowering the rate of heat loss out of your body even when the room air is cold), and for kid-safety. They're not much more expensive than baseboards, and the comfort comes on when the heater does, no waiting for the room to come up to temp. It's possible to control them with occupancy sensor switches in series with line-voltage thermostats in the rooms where you won't be sleeping, but you'd probably want do stick with regular thermostat controls (setback controls, if you like) for the bedrooms.

To get R33 whole-wall performance with 2x6 framing with R20 rock wool cavity fill would take about R20 of continuous exterior insulation. That's about 4.5" of Type-II EPS or 4" of XPS (bad for the environment), or a stackup of 2" of polyiso + 2" EPS (EPS on the exterior side), any of which is buildable.

Thermapan severely exaggerates their R-values, using the performance of Type-II EPS at -50F (see general note #1 at the bottom of page 1: http://www.thermapan.com/pdf/ThermapanDesignHandbook.pdf ). That value is when the AVERAGE temp of the foam is -50F, so with a 70F/21C room temp that means you'll hit that performance when it's -170F (-77C) outdoors. A more useful R-value to use for estimating your peak heating loads would be the +25F (if you're on the northern edge of southern Ontario) or the +40F value (if you're in Windsor or Toronto) which is about R4.75/inch or R4.5/inch respectively. Assuming 1" of OSB skin is worth R1, you have 7.25" of EPS, so the 8.25 SIP performance would be more like R1 + (R4.75/inch x 7.25") = R35.5, or R1 + (R4.5/inch x 7.25")= R33.6, center-panel, without calculating the thermal bridging. The 2x6 stick-built with R20-ish continuous insulation would hit the same ball park, and would likely beat it by some small margin.

Dana,
    Thank you very much! Exactly the response and insight I was looking for! I especially appreciate the insight on Thermapan, further elaborate please if you have any experience with them or know of maybe some better alternatives.
    Thermapan tells me that the whole wall R values are the following including plates:
                        10.25"- R46
                        8.25"- R36.5
                        6.5'- R28
                        with 7/16" OSB

    I am located near the windsor area so I will assume R4.5/inch for the EPS (R4.5x7.25) +R1 = R34.6 maybe a whole wall value of around R32
                                                                                       R4.5/inch for the EPS (R4.5x9.25) +R1 = R42.6 maybe a whole wall value of around R40
 
   From the final 2 builders I am pricing out it seems to be a wash in final cost for the SIPs compared to a 2x6 design with 1.5" exterior foam board that one builder is purposing (claims of R34.5 achieved with this result).
   I believe the sips will be a better built home as in a stronger straighter home with less air leakage.
   What is your opinion on upgrading from the 8.25 wall to the 10.25" wall? It is a $1700 upgrade just in material from Thermapan, I will run my number in my heat calculation.
   If the higher R value was worth the cost, would I be wiser to use 1.5" of spray foam on the entire exterior of the home to help make the home air tight.
   I was then thinking I am best to use 1.5" of spray foam on the underside of the ceiling also connecting to the exterior wall to enclose the entire home.

   I like the radiant cove heater idea, I will look into it more. Do you believe the mini-split will be sufficient for cooling, my only issue is those cold cold days in the heater when I lose efficiency/output from the mini-split for heating.

   Any recommendations on ERV units? I was recommended lifebreath 200 ERV units.

There's no way 2x6 construction with 1.5" of anything but aerogel for the exterior insulation (not commercially available in anything like an affordable cost) would come close to the performance of the 8.25" SIP. If the cost is the same, the SIP wins. (R34 could be a center-cavity value for that assembly, but not after accounting for the thermal bridging of the 2x6 framing.)

Whether it's "worth" going to the thicker SIP depends a bit on what you assume future energy costs will be. But if the upgrade only costs $1700 you might just do it as a hedge against energy price inflation. Even if it doesn't have a clear pay-off, almost nobody complains about having too MUCH R-value. Another aspect to consider, at some point in the not too distant future grid tied rooftop photovoltaic (PV) systems will be under $2/watt, at which point it will be cheaper power than what your utility is charging. You might be able to hit Net Zero Energy with an R40-ish wall, but at an R30 ish wall you may not have enough roof area. (In my area PV is already under $4/watt for 10kw arrays, and will likely hit $2 by 2017 according to both Sanford Bernstein and CitiGroup investment bank' analyses.)

A rough rule of thumb for cooling that works-mostly for code-min houses is that it takes about 1 ton per 1000' of conditioned floor area. The lower the solar heat gain coefficient (SHGC) of your windows, the lower your net cooling load, and most U0.15 windows have fairly low SHGC numbers. You're probably safe to use that rule of thumb, or even increase the feet/ton figure a bit.