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Comment by david422 | Hacker News Reader

> In some climates and energy grids, switching from things like incandescent to LED causes a greater environmental impact

How would that be the case?

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If you live in a climate where it's too cold for heat pumps to function, and rely on electrical (resistive) heating instead, the "waste" heat from the incandescent bulbs offsets the power needed for heating almost 1:1. Replacing those with LED bulbs wouldn't reduce your power requirements at all (you'd just run the heaters more) and the LEB bulbs require more energy and exotic materials to manufacture.

Is there such a thing as too cold for heat pumps though? They drop in efficiency, sure, but still beat resistive heating. Modern ones are still going to be 300% efficient down to -20C or so. With a resistive pre heater I don't see how they'll ever not be more efficient than resistive heating.

My heat pump is a Trane heat pump from 2018 and it goes into emergency heat mode when the temps are below 36, which is off and on for most of the winter. I wonder if I should have it serviced to make sure it's working correctly.

It's partially a function of your heating demands. My sister's emergency heat mode would run all the time in her town house. But she installed a giant insulating curtain over one of her leaky sliders and now it almost never needs to run.

That seems more like she improved her insulation, decreasing her heating needs rather than addressing the temperature cutoff for a heat pump.

I still like the heat pump because in the summer my power bill for cooling a 2600 sq ft home is about $50/month, and in the winter I do have a wood burning stove that I can run to heat the house when the temps are below 36. That and recirc mode on the fan unit can keep my power bills to a minimum.

A heat pump with a sufficiently powerful resistive preheater will be at least as energy-efficient in operation as the resistive heater alone, but it's also much more complex, with a correspondingly higher up-front cost and ongoing maintenance requirements. A resistive heater can consist of little more than a solid-state heating element, a blower fan, and a mechanical thermostat; radiative heaters can even dispense with the fan, which is the least reliable part of the system. A heat pump, by contrast, additionally involves pumps, heat exchangers, and volatile fluids under pressure, generally under the management of some moderately complex logic.

Naturally a heat pump is more complex and thus more maintenance intensive, but it's worth the investment/cost in energy savings in any calculation I've seen (they do tend to require more maintenance).

Cost is one factor, but if you live in, say, rural North Dakota, you may not be able to afford the risk that your main source of heat breaks down in the middle of a blizzard and you can't get anyone in to service it for several days… or weeks. Don't discount the value of predictable reliability.

> If you live in a climate where it's too cold for heat pumps to function

Year round? So you mean the polar regions? Because they can work even at -10F. Efficiency is reduced, but they can work. Crappy ones will cutoff earlier though. If you are not in one of the planet's poles, we have seasons so it's better to use LEDs for at least 3/4 of the time (maybe more as even northern latitudes only have a few really severe winter days).

Modern LED lamps are tiny and use very little material. Incandescent bulbs are no longer considered 'exotic' because of how old the tech is, but tungsten was a very exotic material at some point.

If you live in a climate where it's too cold for heat pumps to function, and rely on electrical (resistive) heating instead

That's the point where I'd strongly consider cryptocurrency mining.

Reminds me of the story of the LED traffic lights that freeze in winter, thus needing an additional heating solution (making them more expensive / error-prone and even less energy-efficient during cold weather): https://www.popularmechanics.com/technology/infrastructure/a...

That was once true but it's no longer a real issue: https://youtu.be/GiYO1TObNz8

5x 100W light bulbs is 0.5kW of heat output which your heating system doesn't need to supply.

Switch to LED and your heating system will need to supply that extra 0.5kW.

In a climate where you are almost always running heating, this makes the benefit of switching to LED much smaller, and considering that they are much less environmentally friendly to produce, it may even tip the scale the other way.

Yes, but. There are few places that need heating 100% of the year and fewer people living there. During the non-heating hours/days, that's just waste heat.

Depending on where the bulbs are located, they may be emitting into a ceiling cavity that exits the building's envelope more quickly than the location of the heating coil. Some bulbs are actually outside the building.

And of course, the heating system can supply 0.5kW for less than 0.5kW of power with heat pumps or (net including generation and transmission) natural gas.

Resistive electrical heating is typically the most expensive heating option available, at least here in Canada. A heat pump uses much less power to provide the same amount of heat, and fossil fuel heating (gas in the west, oil in the east) is often much less expensive than electric.

This really only applies where the heat is frequently so low that heat pumps cannot function. Antarctica, or maybe Siberia or northern Alaska.

Beyond that, heat pumps are still much more efficient than direct electric heating.

Also, if you have air conditioning at any point in the year, those incandescent lights are just going to make your air conditioner work that much harder.

It used to be the case. The energy cost of production was massively higher in their early days and if the waste heat was used, there wasn't a net energy savings. Not so much anymore, especially when increased lifespan is taken into account (it's at least at parity at this point).

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