The intensity does depend on the emissivity of the material, and emissivity is a bit counterintuitive:

https://www.engineeringtoolbox.com/emissivity-coefficients-d_447.html

But less than you’d think, given the extreme coefficient, as human perception of brightness is nonlinear. An object twice as bright as another looks pretty similar to the eye.

Turning electricity into heat is pretty much 100% efficient, but all the other conversions have outrageous conversion losses. Regardless, using solar is still the best option overall.

However, fossil fuels are still widely used, and that’s where the losses play a significant role. In that context, using gas to heat water is the simplest and most efficient setup. Converting the combustion products into electricity just introduces additional losses, further decreasing the overall efficiency.

Thanks for being kind, my logic was still bullshit ;⁠-⁠)

I was somehow wondering, if we lose that energy there anyway, without appliances failing, we could use that as heat source - which isn't too bad of an idea, but just fixing it and using an electric heater would be the actual solution.

I'm still fighting with a fever and headaches since my last business trip and I'm just not that bright at the moment.
And heavy painkillers lowers my inhibitions to just vomit out my thoughts without further reflection ;⁠-⁠)