The way a home or business building is insulated has a huge impact on the heat loss/gain.
We have been trained to believe that the best place to insulate is the attic or ceiling no matter what. This saying started years ago when homes were not insulated at all. Installing insulation in the attic would save the most money, because the air at the ceiling is warmer (since heat rises), and insulating the attic was a lot easier than insulating any other part of the house.
This saying was true when insulating of homes first began, but it has mislead most people of today. If you had a home without any insulation, and you had money to insulate one area of it to an R-5, of course the attic would be the most important place to spend the money. If you insulate your attic to an R-30 but do not insulate anywhere else you will have wasted 2/3 of the insulation. It would be like insulating the attic to R-30 and then removing a couple of windows, and leaving a couple of big holes in the walls.
For years installers did not even consider the basement area in the heat loss calculations, but now installers are starting to realize the considerable loss there is though masonry walls (cement block, poured concrete, brick), even if your basement temperature is kept at 55 to 60 degrees. Your basement walls MUST be insulated to benefit the most from a geothermal heat pump.
It is true that if your home had no insulation installed in it at all, the basement would have the lowest heat loss of any floor that is above the ground level. But, when you have even some insulation in your other walls and ceilings, heat loss calculations then show the basement is now the place of largest loss.
I have been told by many people that the earth is warm and for this reason the basement should not be insulated. Sure the earth is warm: this is where a geothermal heat pump transfers the heat from. The problem is, when there is only a little thermal resistance to the heat transfer through the wall (R-value), then even with a small temperature difference there will be mega BTUHs (BTUs per hour) transferred back into the earth from the basement. It is silly to pay for power to move heat out of the earth and have most of it go right back into the earth through badly/not insulated basement walls.
Some people tell us they don't even heat their basement, so it doesn't need insulation. The facts are this: If you live in a cold climate and you did not heat your basement, it would eventually freeze. Your basement is above freezing in the winter because it absorbs heat from your first floor (and a little bit from the ground around it), which means you are heating it.
In the deep south it is usually more beneficial not to install insulation in the basement because of the cooling benefit of the cooler earth temperatures. Because the earth's temperature is 60 to 75 degrees, there will be a much lower impact on heat loss. But it is the heat loss/gain calculation that accurately tells you whether your basement is gaining or losing heat and how much, and that is how you determine where best to spend your money on insulation.
An example of how large a basement's heat loss can be: In a home in an area where the low temperature can be 10 degrees F, a masonry basement wall (R-1.83) will have an overall average temperature of 32 degrees F. Even if your basement temperature is at the lowest allowable temperature (if the geothermal heat pump is installed there) of 55 degrees F, the heat loss will still be about 22,000BTUH. If the basement walls are insulated to an R-10 the BTUH heat loss would be 3,782... WOW look at the difference!!! A ton and a half smaller furnace can be installed!