Similar to electric baseboards, hydronic heating systems facilitate zone heating as you can keep different rooms at different temperatures.

Though different from electric resistance heating, hydronic systems are ultimately still using electricity to generate heat, so all the same environmental realities apply. Heating the liquid in a hydronic system can be achieved in many ways:

Hydronic radiators and baseboard heaters will transfer heat in the same way as electric resistant heat sources. So for comparison shopping, efficiency of heat generation isn't as much an issue as installation cost and the lifespan of mechanical equipment. Worth noting that noisy baseboard heaters can be fixed, whether electric or water heated, so don't let this irritating trait put you off them.

One advantage to hydronic heating systems is the ability to convert to thermal solar in the future. Solar water heating is much less expensive than solar power generation (photovoltaic).

New homes can be made 'solar ready' which is very inexpensive, adds value for resale, and is worth LEED points. It is a simple matter of running a normal 4 inch plumbing pipe from your attic to your utility room. 

By doing so, installing solar panels (thermal or photovoltaic) is a simple matter of fishing wires or tubes through the pipe rather than an expensive remodelling project involving opening walls. A bit of real estate is required in the basement as well for a storage tank.