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Insulation needs

mrcrankeee's picture

Now that there's a small house fad, craze or whatever, does anyone know if the increased surface area (as buildings get smaller) increase the insulation needs? I'm planning a 650 sq ft house at the moment. Thanks

Certainly as a structure gets (post #213318, reply #1 of 3)

Certainly as a structure gets smaller the ratio of surface area to volume increases.  But keep in mind that total surface area will generally decrease, and that's what determines overall heating/cooling load.

Except that windows are basically "holes" in the outer shell and there may be a tendency for the ratio of window area to wall area to increase with the smaller structure.  Still, total heating/cooling load goes down, but perhaps not as fast as one might expect.

For a smaller structure it's important to be more fussy about sealing all cracks and preventing drafts, as the "threat" areas where air leaks might occur (corners, around windows, along foundation, etc) again do not shrink as rapidly as the volume (and probably not as rapidly as the surface area, even).

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Thank you Dan for the (post #213318, reply #2 of 3)

Thank you Dan for the information. Physics is hard for some of us :) The comment about windows was very appropriate, that is what has currently been suggested to me- some very large windows for the living area.  They are on the south side of the structure. Depending on whose figures are used, its within the recommended limits of passive solar (glazing to total floor area) recommendations. I came up with 82 sq ft and the maximum I found was 120 sq ft. I will be sure to be really paranoid about the air sealing.

Incidental Heat. (post #213318, reply #3 of 3)

As a house gets smaller incidental heat (body heat of the occupants, heat from cooking, heat from the water heater, heat from hot water use, etc.) becomes more of a factor that could substantially diminish heat demand. But, this can also increase cooling demand. There's not a lot of incidental cooling. Passive strateges for heat and ventilation will work especially well in a very small structure.  

You might find the attached to be of interest

thermal1.pdf280.12 KB