I know very little about legal precedent but I'd expect the major meter manufactures (selling into the utility space) to be well incentived to challenge these items best they can, and they have money.Here are the issues, and the reasons that the difference between an air forced system and a boiler/hydronic system are not meaningful for this discussion (ie efficacy issues of sub metering exist for either when method of measurement is measuring heat at point of delivery):In either case, the blower (or pump for a boiler) is the method of 'moving' either air (central air) or water/glycol or equivalent (boiler etc). 

PG propylene glycol one  at one time was pumped through the air vents in hospitals as an anti-bacterial. 

Here, we typically run a 50/50 ratio of glycol/water in the lines.

there is a glycol solution the HVAC can put in the boiler system , it will greatly reduce the freezing point of the water , protecting the pipes and radiators below freezing .MOST reasonable people realize that water freezes when its cold , the frozen pipes were caused by the tenants not having fuel to run the furnace , Damage caused by tenant neglect or abuse should be paid by them

Typically I have seen a glycol system used on a closed loop. 

Radiators (steam, water, glycol, mineral oil) or something else?

Dangers just outside your doorAntifreeze that contains ethylene glycol has a sweet taste that attracts animals but is deadly if consumed in even small quantities; one teaspoon can kill a seven-pound cat.

On the waste water side, we always drained our traps, but glycol should work (especially in the flush which is hard to drain).

I had glycol injected into the hot water baseboard system which allows me to keep the heat on but eliminates the risk of the lines freezing in the event of an extended power outage.

Also more common on upper floors when the building itself is warmer.Your boiler capacity won’t decrease with a glycol solution, it will just have a higher specific heat capacity after creating the mix.