Don Ocean wrote:

TimR wrote:

In cold climates in the winter, a large factor you have missed is
radiative heat transfer to the cold exterior walls. Since radiative
heat transfer depends on the fourth power temperature delta, cold
walls can make you feel cold even when the air is warm and humid.

How cold? To investigate this, you might make TA = 70 F and
TR = 70-R0.66(70-30)/(R20+R0.66) = 68.7 in that BASIC program,
for an R20 wall on a 30 F day.

Well Tim lad... I live in South Dakota.. And I realize that is the
tropical Zone. But we do use forced air heat to the outside walls and
returns to the inside walls...

Then again, warm air rises. Harry Thomason used a central supply with the
heat source in the basement and a long slotted grill near the ceiling to
make a thermal chimeny and floor returns near outside walls to make good
natural airflow.

This keeps the outside walls slightly cooler. We might make up for that
by slightly raising the room temp, and end up using less energy.

Nick