Unless you insulate between the living space & basement/attic (not necessarily recommended) you have to count them as conditioned space, even if it's not a finished space.
But the difference in the total heat load counting the attic will be pretty small compared to the total heat load.
The difference in the basement can be pretty high unless the basement walls/rim joist/foundation sill are all insulated and air sealed (highly recommended.)
Air sealing the attic and foundation by insulating with spray foam takes a HUGE cut out of the infiltration losses. Whether all of the insulation is in the form of spray foam doesn't matter, but retrofit air-sealing with foam is usually easier and more reliable than other methods. In the basement/band joist/foundation sill 1-2" of closed cell foam is recommended, and you can fatten out the R with fiber as-desired. In the attic it depends a bit on your climate. Going more than 2" with closed cell on any part of the house usually has a higher long term greenhouse gas potential (due to the HFC245fa blowing agent) than the energy use it offsets, but that won't meet code min in most areas by itself. Most open cell foam uses water as the blowing agent and doesn't have that issue, but is usually more expensive than cellulose or high-density fiberglass, etc. |