North Idaho ranch house design
Our house will be around 1800 sq ft with a 600 sq ft attached garage. In northern Idaho, zone 6.
The plan is to build slab on grade due to water table issues in my subdivision.
Heat would be hydronic in floor heat. High efficiency natural gas boiler which would both supply hot water to floor and heat domestic hot water. Looking forward to no forced air noise or dust. We have Natural Gas service at street.
Not planning to add Air Conditioning. N Idaho seems to cool down sufficiently at night that one should be able to use a whole house fan to cool the house down enough to not need AC. From what I could see, there were only two nights this summer where that strategy might not have worked. I might run the electrical to spots where I’d add mini splits units just in case I’m wrong about this. From reading on this site I learned that I need to consider the cost of the hole in the ceiling with a whole house fan. I’m evaluating Energy Star cool roofs as a way to help with keeping the house cool.
I plan to insulate under the slab with 4 inches of XPS foam.
The ceiling will be as close to R 60 as I can get. Will use either energy trusses or cantilevered trusses to get significant insulation out to the wall top plate. Does blown in cellulose seem the best choice for that? Is there anything I should consider given that I will have a 2250 cfm fan blowing into the attic space in the summer?
Haven’t decided walls yet. Certainly will be 2X6. May add external rigid foam although that seems to complicate a lot of other things like installing windows and siding. I did a return on investment for adding rigid foam and other potential insulation options. The spreadsheet is attached. I welcome feedback to improve on my installed cost and effective R values. The best upgrade from starting point of R 19 batt seems to be blown fiberglass like Spider with an inch of Polyiso on the interior. Best from an ROI standpoint that is.
My biggest question is would additional money be better spent on other areas than increasing wall R Value? A couple of areas I’m still researching are reducing air infiltration and better windows.
I am not sure how to spec the caulking and sealing of the house, but I certainly want to reduce air infiltration. Is there some standard language to use in a contract with my builder? Assuming I reduce air infiltration sufficiently, I’m thinking about using the Twin Fresh Comfo units. Not sure yet if I need two or four. I like them as they don’t need ducts.
Will spec air tight electrical boxes, use air tight LED ceiling fixtures in place of can lights, etc. No ROI analysis needed for the air tight LED’s, I think it is great technology and currently own a house with can lights and little attic insulation. What an energy waste.
My starting point is to use North Energy Star windows, mostly single hung and casement. Looks like one can get an U of .27 in double pane. I’m looking at windows that have a higher SHGC especially for the southern exposure. Suggestions of a triple pane window with low air infiltration to use for my window ROI would be appreciated.
I will likely add at least 6 kW PV system. Even with so-so net metering in Idaho ROI is 3% without assuming any increase in electrical rates. I’m investigating how to make provisions for future addition of panels up to 8 kW system as I hope to be able to purchase a reasonably priced plug-in hybrid SUV. When will that Mitsubishi Outlander ever arrive in the US???
My contractor is open to my ideas for energy improvements but is not a “green builder”. The only “green builder” in the area didn’t want to bother with my project as they are able to land projects that cost twice or more what mine will. Can’t blame them for that, I would do that same. But it does leave me trying to figure out a lot of this stuff on my own. Fortunately I’m into it and I have this great site as a resource.
Any ideas to help me make this a greener house appreciated.
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