And on the theory side, Joe's sardonic comment on the heat-transfer efficiency of the 'radiator fins' at both sides of the stud notwithstanding, the web that connects these fins is only around 0.02" thick.
Just as the steel standoffs Joe finds acceptable for supporting exterior brick angles limit but do not eliminate the thermal bridge by their (relatively) small cross-sectional area, doesn't the extreme thinness of the web severely limit heat transfer through a structure, especially one which is already protected by continuous exterior insulation?
Plus a substantial anchoring system that ties back into the steel members, there is the issue of thermal conductivity again??
I didn't challenge him, given enough rope, he's already hung himself.
CAVEAT EMPTOR Late to the discussion, but here is a link to the ORNL page covering steel framing with and without the benefit of "outsulation": walls/AWT/Hotbox Test/Lennar Steel/There are new wall calculators available at the same site.
That’s equal thermal resistance wise to about 1 inch of rigid insulation installed on the outside of the steel studs." More information can be found here: A Bridge Too Far.
Uncle Joe is always an entertaining read - "You want romance? Both are much less trouble than a fireplace and much more reliable" - but being in a questioning frame of mind I'd still like to see some empirical quantitative data on the heat transfer through steel studs.
Compared to the heat loss through even a good quality window I can only think the quantities involved are minute, hardly enough to anesthetize the effect of properly installed cavity insulation.
Not particularly trying to make a case for steel studs here, just finding the 'don't bother to insulate the cavity' arguments difficult to follow without actual data in evidence.
They also have a tradition of prefab steel-framed bungalows and light commercial structures dating back to the Victorian period.
I suspect it's a combination of cost, availability and familiarity which keeps US residential framers working with wood.
I did my best to keep the rooms to a good size, but not too small, to avoid the crippling taxes we "enjoy" in this part of the N. Steel offers many benefits, the downsides, mainly thermal conductivity, can be corrected for with double layer taped and staggered rigid panel outsulation.