[voisin]

What about windows? I find buildings with few or small windows to be unmanageably dreary, but the math works out that no matter how insulated you make the walls if you have a good amount of glazing on the walls the effective R value drops quite low.

[jmrm]

You always can use isolated glass panels and wood or plastic frames to prevent that: https://www.energy.gov/energysaver/window-types-and-technolo...

I personally have gas filled glass panels and are pretty good at that, but I wish I had also those that have an IR filter coating that prevent IR heat from entering and from exiting the house. That was a lot more expensive when I installed mine.