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Community and Q&A

Do bulb replacement programs save energy in heating climates?

David Meiland | Posted in Energy Efficiency and Durability on

My question is specifically about heating climates with a predominance of electric heat.

If a house is heated with 100% efficient electric heat, such as baseboard or panel radiators, does replacing incandescent bulbs with CFL or LED bulbs save electricity? Can anyone point to a study that has looked at this issue?

If a house is heated with <100% efficient electric heat (i.e. an electric furnace with ducts in the crawl space with the (perhaps) typical ~30% duct leakage, could bulb replacement actually be a step in the wrong direction? Of course, there are ~4-5 months of the year when heating use is minimal to zero, so waste heat from lighting is not useful during those months, but they are also the months with the longest daylight. And of course, waste heat from bulbs is often near the ceiling, where is may not be of much benefit. I’d like to know about any formal studies that apply to this, if there are any. Utility programs here in the Pacific Northwest all seem to operate bulb replacement programs (cost unknown but probably significant), so presumably there is demonstrated effectiveness.

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  1. GBA Editor
    Martin Holladay | | #1

    I don't think the calculations are particularly complicated. Under the circumstances you describe, swapping incandescents for CFLs will still save energy -- but far less energy than will be saved in Florida.

  2. David Meiland | | #2

    Martin, I don't think they are either, but I'm trying to find out what it looks like from a utility perspective. Utilities buy bulbs and pay people to install them. It almost certainly reduces use, but by how much? I am part of one such program and part of a discussion about the cost-effectiveness of the program.

  3. Aj Builder, Upstate NY Zone 6a | | #3

    My new energy saving refrigerator... has a $75 water filter that alerts to be replaced twice a year. There goes the savings in monetary green.

    As to electric lights I leave on all the lights sometimes in the winter to change the "winter is getting to be a bit long" mood... and do so knowing that the heat is being used too. Just as I post about heat pump water heaters taking heat from winter homes and that my water pipes and drain pipes add heat to my home skewing the idea of saving... heat is heat.... if my home and my water and my lights produce heat along with my refrigerator... it's all good heat... during most of the year where I live.

    Different story in a cooling climate. Use heat pump water heaters and low heat bulbs .... properly place windows to reduce passive heat incursions... etc...


  4. Expert Member
    Dana Dorsett | | #4

    The bulbs in the outdoor sockets DEFINITELY save energy. The ones indoors do only when there isn't a heating load.

    In FL they save more than you might think, since every kwh of power consumed by the light bulb takes another 1/4 kwh to pump out of the house. A 100W bulb is actually responsible for about an average 125w of net power if you're actively cooling. Swapping it out for a 23W CFL saves nearly 100 watts.

    The utility programs are more interested in saving peak power when looking at just the simple-minded bottom line. In areas where their revenues are decoupled and the utility is paid for conservation via the rate structures they factor in how much capital cost is avoided by lowering both the peak transmission amperage and the delayed/avoided cost of building more power generating capacity, which can equal or exceed their marginal fuel-cost per kwh. Putting a bounty on the "spare" refrigerator and handing out CFLs like candy is a lot cheaper than building & maintaining the equivalent amount of generating capacity, or upgrading the conductors & transformers on their grid. Buying nega-watts that way is dirt-cheap, and proven to be effective.

  5. Aj Builder, Upstate NY Zone 6a | | #5

    Unintended consequences Dana...

    So we throw green money at removing second refrigerators... your average neighbor could care less but seeing that they can get rid of the old one and get a new second one... boom.. sold on that money give away....

    Wish I was Fisker and had $500 million tossed to me to play with! Wish I could get $7,000 off a new 1 ton diesel pick up because it is cleaner now that it has a 5 gallon piss pot attached to the exhaust. How about $200 for new work boots and I will promise to walk to work saving the planet from my use of a dinosaur fueled truck... trying to imagine carrying a sheet of plywood one at at time from my lumber store to my build project... better I get $20 rebate for an ax and start building log homes right off the lots... $100 for a tent to stay on said lot to get the work boots to last longer having less miles to travel... I need some relevant rebates Mr. government...

  6. Expert Member
    Dana Dorsett | | #6

    As rare as the replacement-refrigerator is, the benefit is still there, since the new replacement refrigerator uses only about 1/3 the amount of power as that 1970s vintage piece o' scrap. In those cases there's only 2/3 the benefit, of the complete-removal/no-replacement, but in practice the majority of refrigerators removed under bounty-payment programs do not get replaced.

    The net effect on grid baseload of refrigerator bounty programs has been widely studied by both regulators and utilities, since the regulator approved compensation for those programs requires documenting the actual and not merely theoretical effects.

    These are not a federal rebates or (usually) not even a state funded rebates. The money for these programs comes from the rate-payers using that utility. The regulators require that the utility prove that the net result is a net lower cost to the ratepayer, and built into the rate structures. State regulators may (and often do) mandate the utilities pay for at least some amount of efficiency upgrades on the rate-payer's side of the meter whenever that is cheaper than the equivalent amount of new generation or grid infrastructure upgrades required for the equivalent amount of capacity improvement. The utility usually gets to decide how much light-bulb subsidy or refrigerator bounty is optimal for their bottom-line, but it is all overseen by regulators.

  7. GBA Editor
    Martin Holladay | | #7

    It's important to remember that every utility-sponsored refrigerator swap program that I've ever heard of requires the homeowner to surrender the old refrigerator so that it can be scrapped.

    The homeowner isn't allowed to keep the old refrigerator and put it in the garage to keep beer cold.

  8. Expert Member
    Dana Dorsett | | #8

    Most programs require that refrigerator be plugged in and running & demonstrably working first. They usually cut the power cord off even before it's loaded onto the truck- the cords get sold as scrap copper. The refrigerant gets reclaimed in an environmentally-safe manner as well. It usually costs the utility slightly more than what they pay in bounty to run the program due to the cost of the refrigerant reclamation and truck/employee time, but it still pays off in the offset base-load.

  9. Aj Builder, Upstate NY Zone 6a | | #9

    That's it, now where's my beer rebates... to fill my beererator to fill my tummy... and head... with less things of dread..

  10. Marla Umhoefer | | #10

    We have always used incandescent lamps in winter in Florida to heat the house. That way we are able to leave the heat pump off entirely. And we switch to cooler/more efficient ones in cooling months.

  11. Expert Member
    Dana Dorsett | | #11

    Mind you, the heat pump would likely use well under half the power to heat the house that the incandescent bulbs do, provided your house & ducts are reasonably tight. Why do you leave the heat pump off and heat with something less than half as efficient?

    Better grade ductless mini-split heat pumps would use less than 1/4 the power for heating than incandescent bulbs in a FL climate.

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