Steam heat: Generally speaking buildings put up before WWII had a design temp of 0F, meaning rooms could be maintained at 70F (60F?) as long as the outside temperature was 0F or higher. Windows were normally single-paned and drafty. Individual radiators in each room were sized to allow this.
Problem #1. Now in 2015, even the oldest buildings have double-paned windows with few if any leaks. As a result rooms are often overheated. Common sense dictates that slower valves be used in overheated rooms (to save energy) but that concept is far too complicated for most to understand.
Many pre-WWII buildings and nearly all 1-3 family pre-WWII homes are designed with low-tech, LOW pressure (as in steam pressure under TWO psi) single pipe systems that are dependent on the non-negotiability of laws of physics to run efficiently.
Problem #2: There are very few steam heat specialists alive today who actually understand why these systems were designed the way they were. Many homes have 'updates' made decades ago causing losses in efficiency. Scams abound: You see, sir, your system has to be replaced because it is old and inefficient and I'll conveniently not tell you that it worked JUST FINE 100 years ago because the technicians back then knew what they were doing.
I've had some so-called experts seriously didn't understand that no, the steam pipes CAN'T be level because then the condensate (sorry, was that too big a word for you?) can't flow back into the boiler. No, you CAN'T just take the insulation off the first 15' of steam pipe without compensating for the resultant heat loss and expect the system operate the same way. No, you CAN'T replace a clogged 'E' valve with a 'C' and expect the room to be equally warm. No, this is NOT my personal philosophy of steam heat. These are laws of physics! I know that was long-winded, but really I've barely scratched the surface. The incompetence of steam 'experts' is mind-blowing.
With a PTAC system, nobody has to understand anything. You can just slap it in, connect the wires, and stick the person living there with a needlessly high electric bill. Launderess' most excellent point regarding humidity really needs more emphasis, IMO. These past several summers have been extremely humid, to the point that dehumidification must be considered independently of cooling. As discussed in another thread, recent changes in residential a/c units have rendered them more efficient at cooling (thereby satisfying the 'goobermint') AND less efficient at dehumdification. Anyone see the problem here in the East?
The only solution I see on an individual level is to do it all ourselves. Apartment too clammy, buy a dehumidifier. Hot water luke warm? Make sure your dishwashers and washers can heat their own water. Landlord replaced your 4' steam radiator with 4' of hot water baseboard? Buy an electric heater to compensate for the unacknowledged 50% reduction in heat output.
It's beyond absurd.
Jim