Hugelkultur and heat

I have noticed some questions and comments about hugelkultur beds providing heat for plants growing on and/or around them.

I am thinking that mostly this relates to the hugel being warmed by insolation faster than the mass of the earth below and some combination of reflected and radiated heat benefiting plants near the southern face.

I do not think that decomposition of the material in the bed adds much, if anything, to the heating. The wood is undergoing fungal decomposition and should not be generating heat the way a bacterial compost can.

I get the feeling from some comments that people are thinking of the hugelbed as a sort of big compost pile and expecting heat generated from decomposition.

Am I generally on target, the warming benefits having more to do with good angles for insolation and the smaller mass than with any biological process going on?

More significant is suns heating effect due to surface area/ angle and contour regarding wind protection, cool air run off and warm air retention.