The rebound effect strikes again

Not a surprise to those who know about William Jevons. Efficiency promotes growth.

In a surprise finding, the study into the long-term effect of loft and cavity wall insulation in England and Wales showed that the fall in gas consumption for each household was small, with all energy savings disappearing by the fourth year after it had been fitted.

Policy experts at the University of Cambridge said the findings suggested a “rebound effect” in energy use, where changing behavior cancelled out the reductions in gas use. They also suggested that fitting insulation often happened alongside the building of house extensions, which use extra energy. For households with conservatories, any gains in energy efficiency disappeared after the first year.



The Rebound Effect is very real!

When people feel too safe they jump off bridges with a rubber bungee cord on their ankle and out of asirplanes without a parachute.

When investors make a fortune in the market they buy extravagant jets, yachts, or both.

The Captain

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But is that a bad thing? Resources are being used more efficiently. The same amount of resources are providing more benefits.

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If the goal is to reduce energy use then the rebound effect works against that reduction.



Totally true in my case. I had 13 inches of insulation blown in over a six inch bat.

My inside temp I could then turn up from 63 F to 72F.

I saved no money. I am now much more comfortable for the same amount of money. In that regard as I aged the temp would have gone up using more and more energy even at lower temperatures would have been used.

Do my medical bills go down? Possibly.
Does my productivity rise? Yes.
Am I happier? Yes.
Did other things happen that improved my life and health? Yes. I got more organized in other things including adding a standing desk converter. I just about never sit while working. With the increased health I am cooking and exercising more.

All of that because of the temperature? A certain amount of it yes in part.

There is more to life than a straight line.


Yes and no. There are always unintended consequences. Read an article a few years ago about changing to LED lights. Good, more efficient, less ambient heat, personally knew my A/C ran less. Where is the bad/unintended consequence? People start using more decorative lighting/ landscape lighting. Energy usage evens out over time but with outdoor lighting, potentially have adverse effects on flora/fauna by disrupting circadian rhythms.

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This is definitely true. Once LED lighting arrived, people added all sorts of new lighting. Backlights on large screen TVs, fancy multicolor pool lighting, foliage lighting, elaborate Christmas lights, etc. BUT, in this particular case, the rebound has no chance of catching up to previous usage because 100W (incandescent bulb) versus 9W (equivalent LED bulb) is just so much lower. Nobody is using 11 times as much lighting to fully rebound.


True, but more people are adding the new lightings which offsets some of that 11 times (but not 11 times as many people LOL).


TV v Computer v Cellphone…TVs are truly the wasters of wattage.

I think it is ordered as such…from memory…

10 cents per hour, 2 cents per hour and 1 cent per hour of usage.

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A friend just replaced his 80% efficient furnace with a 95% efficient “on demand” furnace to heat the water in the radiator heating system. He also replaced the hot water heater with an “on demand” version. He has lived in the house for over 40 years (bought about 1980), so he has had time to evaluate the effectiveness of various systems.

The radiators used to be reasonably warm with the old furnace(s). Now, the first-floor radiators are HOT when the system is running. He had to put boards across the tops of the first-floor radiators to provide additional usable space to put things and dispel some of the heat to the rest of the room (the radiators are, of course, under the windows). The cats really like resting on the boards. Let’s just say I saw the cats “in action” . The second-floor radiators are not as hot as those on the first floor, but are definitely MUCH warmer than historically. Payback on both investments estimated at 8-10 yrs. He spends more for electricity but saves far more on his monthly gas bill (especially during the winter).

Now he has far more usable space in the basement, where the old furnace and hot water heater used to be. That is the next project.


@jerryab2 - Great to hear of your friend’s investment in their heating system upgrade.

It’s unclear to me what type of radiators he has. Does he have the old style cast iron stand up radiators, or the old style cast iron baseboard radiators, or the new style slant-fin baseboard radiators? Our house was built in 1983 and has the slant-fin baseboard radiators which mostly go along the outside walls of our home.

I’ve been reluctant to do the homework on this, as I’ve heard some horror stories with the new highly-efficient burners from some of my golf buddies.

I’m happy to hear that it seems like they are making progress in improving these units.


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He has the cast iron stand up radiators. House was built 1912? Wall insulation was blown-in shortly after they bought the house. Then I helped to install insulation inside the attic roof (on the inside–small wood blocks nailed to the roof and sheets of rigid insulation installed on the blocks–so there was an open air flow gap between the roof and the insulation). I think it was two layers of insulation, then sheetrock to finish the attic.

Those baseboard heaters are inefficient and, IMO, ineffective. I have your type of baseboard heating here and I use a separate space heater to keep the apt comfortable. The baseboard units tend to be connected end-to-end if they go room-to-room, and only the first room gets real heat. The rest of the rooms in that run need space heaters. If each room has its own baseboard heater connected directly to the hot water source for heat, then it would be much better. Each room would essentially have its own thermostat controls (and not for multiple rooms on one thermostat).

I have lived in a building with central heat and AC running in finned radiators just below the ceiling (maybe 12" below?) and about 24" or so away from the windows. That system used a 2-room connected system (LR and one BR on one thermostat) and two other bedrooms with one thermostat for the heat/AC for those two rooms. It was designed/built in early 1970s. Have not seen anything like it since. Seemed to work ok, but I also ran a fan–so the air would circulate.