I am building a grout filled CMU house in the Ozarks. I have limited funds at this point and so I would like to focus my budget on thermal control where it will be needed most (i.e. heating / cooling). So far, I will have a large East facing deck roof which provides an 8' "overhang", and a 3 foot overhang around the other elevations. The west facing elevation gets a lot of tree shade around 4pm. I'll be using engineered trusses with a 10 inch heel for plenty of insulation in the ceiling. The steel roof will be painted white. For heating, I will have a good cast iron wood burning stove with an unlimited supply of free hardwood seasoned logs. All doors and windows will be tightly sealed. Rooms will have adjustable vents (to outside) that can be shut as needed. The house is 51 feet N to S and 26 feet E to W ... and the floor is concrete as well.

At this point I am not sure what to expect. Are the winter nights going to be the challenge or the hot summer days? .. in other words .. should I expect it to be harder to cool than to heat or vice versa? As long as I know which is tougher, then I can focus more energy and budget there.

  • This question is too broad, partly because it relies on substantial speculation and hypothetical situations.
    – isherwood
    Jun 15 at 18:08
  • We put 8" of insulation under our concrete floor - will you have any?
    – Solar Mike
    Jun 15 at 18:40
  • Wrap ~4" of foam around the outside of your block walls (and stucco over it for a finish layer, or use siding, whatever) and you have a nice thermal mass enclosed in insulation. Otherwise you have mentioned NO insulation in the walls, and grouted concrete block is not a decent insulator at all...freeze and boil.
    – Ecnerwal
    Jun 15 at 20:10
  • What are you planning to use for insulation? (Your construction technique does have the benefit of lending itself well to continuous exterior insulation, and no, foam isn't the only game in town either) Jun 15 at 23:46
  • If I remember correctly the CMU blocks I last used had an R value of ~50 so it depends on the actual temps high and lows for the area and the number of heating days compared to cooling days. The government has statics by zip code for most of the US by zip code, I would start with that information and your actual site wether it is shaded or full sun.
    – Ed Beal
    Jun 16 at 14:57

CMU has different day/night swing than insulated wood.

If summer nights are cool at altitude you'll have cool summer days inside.

Your challenge is thermal inertia in the winter: the time and energy it takes to get the inside comfortable after you arrive, and the cost of lost energy left in the walls when you leave.

To be more precise and come up with a quantitative analysis you'll have to model your home, talk to neighbours, or visit similar areas elsewhere in the Ozarks.


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