[Dylan16807]

Thermal infrared doesn't go through glass. You only lose a negligible amount of visible light. It's still 100% efficient as an integer percent.

[elil17]

I assume by “thermal infrared” you mean the IR produced by approximately room temperature objects. Incandescent bulbs produce much higher energy infrared because the filament reaches about 2000 Celsius. Those higher energy waves can go through glass.

[Dylan16807]

Right, that's true, I was thinking about it wrong.

Still, not much is going to hit a window on average. So maybe 90% efficient.