Heating systems for tile vary. Some just warm the floor while others can be set to the ambient temperature. I prefer NU-Heat as the thermostat can be set ambient or timed. They can also be set wireless if that matters to you.

Electric heating systems are just to warm the floor. BUT-- when the floor feels warm, the rest of the room won't feel quite so cold, either. If you want something that will warm the room, you're looking for hydronic radiant heat (water tubes running under the floor). But that's a primary heating system. As for the towel warmer, I've had a free standing towel warmer in my bathroom for about 3 years now. It's great to drape a towel over right by the shower. But I honestly can't remember the last time I turned it on. And you talk about cold-- I'm in Maine. :-)

Our MB is over our unheated garage. Floor heat warms the floor nicely and does contribute to the overall warmth of the room as well. We used Nu-Heat custom mats.

What about a heat lamp over the shower as well as the floor heat?

We may end up building the master bedroom/bath on a slab--and if we do, I definitely want floor heat--but since we're looking at a curbless/doorless shower, too, I think a timed heat lamp above the shower might be lovely.

"will underfloor heating help warm the room at all, or just stop the floor being chilly?"

A true underfloor radiant heating system will heat the room. Basic under-tile heat mats or cables can do what the others' wrote; simply warm the floor, or some are capable of warming a room.

"2. what wattage of towel heater is needed to make a difference to air temp? Over 150? Over 400?"

Look at the BTU output. Most "towel warmers" struggle to simply warm towels. If you want a "towel warmer" that will heat a room, look at Runtal. There are other brands as well. Some of their warmers are hydronic, some are electric. For room heat, a very generic rule-of-thumb...which is exactly, that...a generic rule-of-thumb... recommendation would be to get something that can output about 25-30BTU per sqft of room. You have a 10' x 10' room, 100sqft, you'd look at a unit that can output 2500-3000BTU. There's always Manual J for a more accurate number.

"3. whats the most energy efficient and non-ugly ;) way to heat a bathroom?"

First, stop the loss. Air seal the room to prevent air infiltration through the house's thermal envelope, and properly install whatever insulation that you use.

Then address heat requirements. In a light-use climate like yours, anything "radiant floor" you'd want low-mass for quick response times. Simple under-tile cables or mat systems, or if you did go with a true underfloor hydronic, a low-mass staple-up system would probably serve you best.

If you pursue the towel warmer route, Runtal and Runtal-like towel warmers come in a variety of sizes (BTU outputs) and styles. They blend well with most decor.

Most cost-effective would likely be a Runtal-type warmer with a few judiciously placed bathroom floor rugs set on the tile.

I had hoped to use a hydronic floor heating system as my sole heating source in my bathroom but with high ceilings and 104 sq ft with three large windows in the room the heat exchange formula used for code, I live in New England, said I also needed a second heat source. I went with Nuheat floors, much cheaper than hydronic and since it is meant only as a scondary source it was the best option, and a radiator towel rack by Myson. It is actually a hydronic radiator sourced to my square area with towel racks around it... I must say that although code would not permit my floor to be a sole heat source I have never even turned on the rad once in a year. The floor seems to heat the volumous room well even with bellow freezing weather.

here is my myson towel radiator, this was a big splurge that is mostly now decorative for it would make the space too warm if used with my floors on.

Thanks for the replies everyone!

I'll discuss output of underfloor heaters with the electrician: looking at NuHeat now.

I've asked team to insulate under the (ground floor, over crawlspace) bathroom too to prevent heat loss. I have planned a large window in the bathroom - 3' wide, 8' tall - which will be laminated safety glass, but I don't think that's exactly going to help warm the room!

Are there Runtal-like warmers that aren't as expensive? I'll search for ones that output 2500-3000 BTU: thanks for that direction.

Rorah, turn off the heat and use that Myson! lol

Many of the Runtal towel warmers produce enough BTUs to help heat a bathroom.

There is also Tuzio and several in the Amba collection that will give off some radiant heat.

Runtal Towel Warmers

Tuzio Towel Warmers

Amba Towel Warmers