Heating/Cooling SIPS built home – Washington NH
I am considering a SIPS built home, perhaps using CHS and EPS – New England, in Washington NH, and possibly on frost protected shallow foundation, slab on grade. It is possible that this is only used “3 season” so not sure if that would be bad for frost protected shallow foundation, slab on grade.
The building envelope will be quite small – about 800 sf. due to wetland considerations. One B/R w/ shower/toilet downstairs, one bedroom w/ powder room upstairs.
Upstairs might be completely open with bed, couch, etc. Downstairs will have bedroom, bathroom, laundry and the rest – open with kitchen etc exposed to “great room”.
My current thought is one ductless mini split upstairs, one down (two compressors, or one w/ two heads). Then an oil filled electric radiant heat for each enclosed area.
I’d like to hear thoughts on the heating plan, thoughts on air exchange. frost protected shallow foundation, slab on grade, SIPS built homes – all of it!
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Not my area of expertise but I'll share what I've learned here about frost protected shallow foundations and if I blow it hopefully when of the experts will correct me.
There are 2 approaches, one for heated buildings (#1) and one for unheated buildings (#2).
#1 puts no insulation under the slab and relies on the heated house warming the earth below.
#2 insulates under the full area of the slab so that the slab is thermally separate from the ground below. This approach works for BOTH heated and unheated buildings. You would want to use this approach.
Of course, there are a lot more details to it. But this should get you started on the right path.
The ductless heads are fine, ducted would probably be more comfortable. I'd install electric baseboard in the entire building, it's a cheap emergency backup.
Do the mini-splits fail? Of course, in a power outage baseboard heat won't work. Baseboard gather's dust - I prefer the european flat, wall mounted radiators like this: https://www.purmo.com/public/prod/bcd2c0f2-6156-46c6-99cd-ddcde7354507/15745/f6b5accb97fb9e5b711f910b32acdbc0/en-node-yali-p-type-21-h600-l600-livingroom-2000x2000px-desktop810x810.jpg
Of course, all equipment fails! Heat pumps also eventually lose capacity and even stop at low temperatures (about -20F for the highest performing, lower for others). You’re right about the power outages of course.
As JGSG posted: Whether you intend to supply some minimal heat year round will determine which type of FPSF you use.
I agree with Paul - baseboards are cheap insurance and would be a good heat source for the enclosed rooms. I don't see any advantage to the oil filled heaters.
Plan on including a ducted EV for ventilation.
When installed diligently SIPs work well. The downsides are they are outside the skill-set of most builders, and are one of the few methods of construction which can experience widespread, irremediable failure.
What is considered "minimal heat" year round? Also, are you familiar w/ a skillful builder for SIPS>
There are guides for unheated and heated buildings. The design of the insulation depends on a variety of factors including the R-value of the floor, and how warm the building above will be.
I'm on the West Coast. Hopefully someone from New England can recommend a local builder.
I wasn't sure what you were considering as radiant heaters. I agree those wall mounted units are probably a good choice.
thank you for the update. Are you living in a super insulated home?
No. We live in a small house I built thirty years ago. Between our temperate climate here on Vancouver Island, and low energy prices, the moderately efficient all electric house consumes about $5 of power a day - which isn't much of an incentive to make improvements.
Consider skipping the SIPs. They were a cool idea but the market has decided that the costs outweigh the benefits. You can build walls with a higher R value for less money using greener materials that are repairable.