> more efficient [electric motor] designs are simply more delicate
Nope. This argument works for portable power tools (lighter designs are more delicate), but not for stationary motors. The efficiency gains for stationary motors have primarily come from better drive circuitry.
> running closer to their optimal maximum which means ... running hotter in general
This is utterly wrong. The maximum power is defined by the amount of copper (and thermal resistance to ambient), which is constrained by cost/weight. Warmer windings actually mean higher ohmic losses, so the manufacturer's savings actually mean higher electricity consumption.
> I recently read that ... your average ceiling fan was something like 30% efficient up until fairly recently
Citation needed, especially with your implication that this was due to the motor itself (as opposed to say shape of blades and electrical power factor)
I'm probably wrong on the technical reasons specifically (my motor experience is limited to robotics and rc cars), but its only recently you could buy 29-35 watt ceiling fans due to the use of DC motors:
You can google up articles from the early 2000s were it was conventional wisdom that the fan ran 100 watts.
I did read a bit about motor design but I can't find it now, but clearly the differences in wattage are real. I believe the newer ones are brushless DC vs the single phase induction of old. I imagine newer fan design helps too.
This Kensgrove is a whopping 72" but with a DC brushless motor. 31 watts on the highest setting.
Sure, fans have become more energy optimized. That doesn't support the implication that the lightness was required to get the modern lower energy usage, nor that a better built (heavier) motor wouldn't be more efficient and last longer. That lack of longevity is what the "motor weighers" are lamenting - a major reason this whole topic is important is that we're currently unable to buy new more efficient appliances that will also last long.
> newer ones are brushless DC vs the single phase induction of old. I imagine newer fan design helps too.
Yes, this is the advance in drive circuitry that I referred to - same with the "DC motor" fans. It's still a fact that at the current consumer design point, adding more copper to the windings will increase weight, efficiency, and longevity.
Nope. This argument works for portable power tools (lighter designs are more delicate), but not for stationary motors. The efficiency gains for stationary motors have primarily come from better drive circuitry.
> running closer to their optimal maximum which means ... running hotter in general
This is utterly wrong. The maximum power is defined by the amount of copper (and thermal resistance to ambient), which is constrained by cost/weight. Warmer windings actually mean higher ohmic losses, so the manufacturer's savings actually mean higher electricity consumption.
> I recently read that ... your average ceiling fan was something like 30% efficient up until fairly recently
Citation needed, especially with your implication that this was due to the motor itself (as opposed to say shape of blades and electrical power factor)