Lightbulb ferm heater + new bulbs?

I want to build a lightbulb + paintcan fermentation heater like so:

http://brewstands.com/fermentation-heater.html

I've read to use a 60-watt bulb, but most of the literature I've seen on the topic is a few years old. How has the situation changed since the recent change in bulb manufacturing in the USA?

I hear the new tungsten bulbs are more efficient, requiring something like 20% less energy for the same light output. Obviously less energy means less heat, but I was never completely clear on how much of the heat output of a light bulb is directly related to its light output, either.

To wit: Should I use a new-series incandescent bulb in my build, or has the decline of incandescents mooted this heater?

FWIW I use a 100W infared reptile lamp. No harmful UV rays

Context is everything: when dialing up a heat source, the chamber volume and outside ambient temperature probably matters, and you could throw in the insulation factor, as well, when comparing consumer appliances versus plywood and foam home-built chambers.

So, fwiw, I use a 40w standard incandescent in a 17 cf fridge located in an above-grade "basement". In the depths of winter the space can get down to around 55°F...

Cheers!

I would just experiment. If you need to go up to a 100 or 120 it shouldn't be a big deal, incandescent bulbs are pretty cheap.

Issue is that this fridge is outside year round, in Vermont. I dunno if I'll be brewing anyway when it's five below zero, but ideally my heating setup would be able to keep its end up in that kind of conditions.

So far I've gotten pretty divided answers as to whether or not that's feasible, or even realistic.

I'm in the same boat and I just started a new thread asking if anyone has any experience with outdoor fermentation chambers in extreme temps.

https://www.homebrewtalk.com/f11/heating-outdoor-fermentation-chamber-cold-weather-428122/#post5451381