I'm looking for advice on heating my 100+ year old 3-flat (no tenants,
just me and my sister).

It is currently heated by cast iron gas space heaters, 1 or 2 units per
floor, approximately 35000 BTU per heater. The brick building, for the
most part, has no insulation. It has an unheated glorified crawl
space, 3-5 feet in height. New windows and doors, so leaking air is
not a problem.

I'm remodeling the place and my contractor has suggested lowering the
10 foot ceilings to install central heat. I don't want to do that, but
I'm at a loss for alternatives. I'd like to install radiant floor heat
on the first floor, and gas fireplaces or heaters on the other floors.
I really like my old space heaters, but my sister doesn't, and we
should probably replace them anyway. I have a newer space heater that
doesn't work as well, plus it's downright ugly. Direct vent gas
firelplaces are being considered, but that requires punching a hole in
the wall, which I'm not too keen on.

Vent-free gas heaters are out of the question, as the aggrevate my
respiratory problems. Likewise for any heating system with a fan.

I'm afraid to convert to electrical heat completely, as I have no idea
what it would cost. Ideally, I would love to have a dual fuel system
(gas/electric), to be able to take advantage of whichever fuel is
cheaper. I live in Chicago, and electric rates are due to rise around
20% soon.

What are my options? (I plan to stay in this building for another 8-10
years.)

Karen