Here’s an additional piece of nuance that these conversations always overlook: how much waste heat is actually waste heat? Where I am in Quebec, we have hydroelectric electricity in spades and since it is so cheap many homes have electric baseboard heating. Couple that with the fact that in Quebec we run our heaters for 7 months of the year, and that means that 60% of the time your waste heat is not entirely wasted. Assuming at least 75% of the infrared radiation from the bulb remains within your home, then on average year-round 45% of the thermal energy is not wasted and your 90% efficiency improvement of LEDs suddenly only looks like a 50% improvement.