They didn’t say most of the heat was carried by photons. They said the photons turn into heat when they’re absorbed by atoms. That’s how radiative heat works, and yeah, most of the heat from a space heater isn’t radiative, but some is. All of the light you see turns into heat, so it isn’t lost. A tiny fraction will be lost through some means, but approximately 100% is turned into heat in the room at some point.
They didn’t say most of the heat was carried by photons. They said the photons turn into heat when they’re absorbed by atoms. That’s how radiative heat works, and yeah, most of the heat from a space heater isn’t radiative, but some is. All of the light you see turns into heat, so it isn’t lost. A tiny fraction will be lost through some means, but approximately 100% is turned into heat in the room at some point.