What is your application? If it is a remodel without pre-existing radiant heating installed then most would use electrical for a bathroom or other small area for comfort versus heating. If it is new construction or a replacement system, then you would use a standard radiant heating system with a 'boiler' type unit that can be powered by solar, geothermal, gas, etc. Whether it can be used under hardwood floors depends on the hardwood flooring material. You would not use an electrical "mat" for whole house primary heating - it is simply for foot comfort.

The application is critical to understand which system will work the best:

Small area with a retrofit (renovation) like kitchen or bath = high-end electric mats.

Large install in a NEW BUILD (bare land waiting to have a house built) = hydronic for efficiency.

Off-gassing will be directly attached to the floor you buy, not the heating system you install. Solid hardwood with site finishing = least likely to off gas (not including the cure time). Low-end engineered hardwood for $1.99/sf out of Asia = huge off-gassing concerns.

Thanks for the
responses! The area is about 490 ft.² of
new construction and we’ve been leaning toward a hydronic system.

The size you are talking about is the size of a great room...not whole home heating system. Will you have another heat source for the rest of the home?

One way around the gassing issue is to use stained and polished concrete floors. If I were building a home in a cold climate I would 100% go for radiant heating. It is the most comfortable heat system around.

Thanks for the additional info! The house will also have natural gas/hot water heat.

Have an idea of the flooring you want, and then look at systems that will work with it. Over the past 20 years, we've designed and installed electrical systems for just about any floor covering and sized area, but it helps to have an idea of what you are planning first so the system can work with the room.

The radiant heat product we usually use is WarmBoard. Check out this link for their Houzz page.