Instructables

Increase your refrigerator's efficiency in 10 minutes for about $2

Picture of Increase your refrigerator's efficiency in 10 minutes for about $2
When I was a little kid, supermarkets often had these hanging plastic sheets with slits cut in them over the upright refrigerated produce and dairy sections to keep the cool air in while allowing people to easily reach through and grab the groceries.

It was so easy that no one thought twice about it, but for some reason they all disappeared.

One day I opened my refrigerator, felt all the cool air coming out, heard the compressor kick on instantly, and I still wasn't sure what I wanted, so I stood there like an idiot, trying to decide while being distracted by my money (in the form of electrically generated coldness) spilling all over the floor for no particularly good reason.

So I decided to do something about it.

[UPDATE:
In response to all the comments - com'on guys!  Don't you read the other comments that other people already posted before you write your own? 
More specifically:

"Most of the heat is stored in the items in the fridge" - this is true, IF the fridge is mostly full.  If it is sometimes fairly empty, it will improve its heat holding ability, as well as require less cycling of the compressor, to put full, sealed, bottles of water inside to take up space.

"The items in the door will be warmer"  - Possibly.  Good question.  I'll put a thermometer in there and find out.  I personally don't keep any dairy in the door (mostly condiments and cool water for drinking) so I hadn't thought of that possibility as a negative.

"Why not use velcro / magnets / spring curtain rod instead of tape, so it's removable" - Not a bad idea, though I'm not at all sure how well it would stay in place.  If I happened to have any of those materials lying around, I might try it, but as I have a huge rarely used roll of packing tape, that's what I used.  I wouldn't take it out when loading the fridge after shopping anyway, as thats when it is most useful.

"This won't make a huge difference in energy use" - Almost none of the energy saving ideas I propose will, alone, make a huge difference.  Cumulatively, though, I have a monthly energy usage of under 60kWh (for a two person, one cat, household - with high speed internet, two computers, 27"TV, DVR, videogame systems, microwave, etc) for a cost of less than $8, compared to the US household average energy use of just under 1000kWh.
60 vs 1000.
I feel that speaks for itself.
For a bunch of other tips that won't save that much by themselves, but add up to $1000s in annual savings all added up, see: http://www.instructables.com/id/Not-your-average-save-energy-advice-use-less-en/ ]

 
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catgil317 days ago

It's not just a savings by way of less electricity required to cool the contents, it's also in Food savings. Just returning from 2 weeks of travel, I found the watercress still fully green. No way would they have lasted that long if I was opening the frig on my routine basis.

My only concern is whether vinyl is a healthy material.. The smell of new vinyl is pretty strong. I would not want vinyl outgassing into my food supply... maybe if it's left to sun and outgass for a while first...

JPcreo12 months ago
The instructables it’s simple and valuable. Thanks.
It’s most valuable for one or two peoples I believe.. If I would do that at my refrigerator I could get scorned by my kids.
Other proactive action can help too as to clean the back of the refrigerator (Heat-exchanging pipes) periodically, like once or twice per year should suffice.

grapenut1 year ago
I love this idea and here's why: You mention seeing these at grocery stores when you were younger but don't know why they disappeared. 1st. The fact that you actually saw these things in use on a relatively large scale, at commercial type grocers; to me speaks volumes. Think about it; -would those retailers actually have used those type energy saving devices if they didn't show SIGNIFICANT savings benefits that could be SEEN? I would imagine that during the fuel crisis of the 70's power bills soared... 2nd: So why then did they disappear? The answer is simple: Big time grocers study this kind of stuff very closely; and the truth is the overwhelming vast majority of grocery store shoppers (lots of women and elder ladies) much prefer groceries with nice clean lines, and aesthetically picture perfect displays (not the loose plastic flappy things)...But I strongly suspect that the energy savings from this (for an open grocery store shelving system) is quite significant in terms of percentages (like more than 10%; who knows maybe even like 30% or so). I suspect one of the reasons many might make loosely framed comments such as "this won't save that much" is due to the fact that modern fridges aren't really considered to be the energy hogs we often suspect them to be...So 20% savings in operating costs for something that uses less than 5% could be kinda hard to see; but no doubt SIGNIFICANT with regard to the refrigerator's overall energy use.
I know it's a bit late of a reply, but... I still see these curtains in SOME stores.
Specifically, there are 2-3 large liqueur stores in the Wisconsin/Illinois area that use them on the refrigerators that contain the cases of beer. Also, seen in use on virtually ALL walk-in refrigerated supply rooms. That includes things like the local Jewel butcher-to-store doors, and even the frozen food supply area of the local no-name grocery(they have the curtain mounted behind a normal door).
Broom1 year ago
Ignore the haters. Don't even address them. This is a good idea, and that's what this site is for.
wgrube1 year ago
Great idea!!! I'll try this!
grapenut1 year ago
I have seen clear shower curtains at the big discount stores for as low as $2.99, or maybe it was $3.99. Anyways you would just have to fold it sideways instead of lengthways to double it up. Mold resistant too...
rsmaudsley1 year ago
I honestly don't know if I'd take the time to do this, but I think it's a great idea.  One way you could check to see if it is really saving any money is to use a Kill-o-watt meter to measure the watts used be your fridge, with and without the plastic material.

Here's the product website


I've used it to measure the wattage used by various appliances to see where our electrical money was going.  I also use it to test Christmas lights to makre sure I haven't strung too many together
Great idea. Going to start on it soon. Thx
Great idea! It's good to think about these things, even if they don't end up saving money. I hate to point out the obvious, but buying the smallest refrigerator that fits one's needs is probably the biggest possible money saver. I switched from standard American full size fridges to the fridges about 1/3 the size, standard in most everywhere else in the world. Sometimes it gets to be a bit of a Tetris game, but it stops me from wasting food, by opening too many containers or by buying more stuff than I can use up in time. I have a separate little freezer that is probably not so efficient, but still probably uses a whole lot less energy than most options.

For efficiency, I find the trick really is in thinking smaller. I don't have any room for water bottles on the door, but if I did, that would make sense. The more full the fridge, the colder it stays. cheers!
JacobAziza (author)  prickly vegan1 year ago
I agree 100%.

I am still a little bitter about the fact that when I bought a new fridge earlier this year (the old one leaked its refrigerant), I was not eligible for the EnergyStar rebate BECAUSE it was a less-than-full-size model - even though this is my primary, and only, fridge. The one I got was EnergyStar rated, and it uses LESS power than ANY of the ones that qualify for the rebate, but the assumption is that any one who bought it must be using it for something other than the main household fridge. We have to move society as a whole away from the assumption that everything needs to be big and expensive as the standard.
Check out my energy guide instructable, it goes right along with this concept
DustBunny1 year ago
I like the plastic idea, especially if you have kids who like to stand there in front of the open door hoping something new magically shows up.

Since I have glass shelves in the refrigerator I'm going to try hanging the plastic from each shelf to make it easier to get things out with less air transfer. 

The less the compressor kicks in, the longer it will last. Fortunately ours was still under warranty when the compressor died.

Instead of using water bottles, my mother keeps lots of cans of soda in her refrigerator (her grandkids love that)
I'm looking at this, and thinking it could occasionally be a hassle to load/clean the fridge. So, rather than tape in the curtain, why mount it on a strip of some kind, that is held in by magnets?

That way, you could remove it easily for maintenance of the fridge (or cleaning goop off the curtain, which is bound to eventually happen. And reinstallation would be a cinch.

Self Adhesive VELCRO appears to me to be the best way! (magnets won't aqttach to the plastic interior of many refrigerator models...) But your idea is good. Amclaussen.
Cool!
What a great idea, I have trouble with my freezer frosting up too (as it's an older style fridge that requires you to open both the large fridge door and the smaller freezer door to access the freezer). Perhaps something like this would help for the freezer section too?
If you have that old of a fridge, you need to replace it with an energy-star model - that will go much further than plastic stripson an energy savings. The electricity savings will probably pay for it compared to what you are paying now with that old fridge.
CatalinRO1 year ago
That's a nice idea, I have to give it a try. I saw that there are some comments (in my opinion) related to the mindset change and to the difficulty to improve things. In spite of all, keep up the good work on saving energy! :)
platdujour1 year ago
Brilliant.
insydney1 year ago
one thing thats not absolutely clear, did you overlap the 1st and 2nd layers? or do they just lay so the pieces double up exactly ?
i assume an overlap would seal better however might make retrieving items harder, like swimming thru seaweed :)
JacobAziza (author)  insydney1 year ago
I lined them up exactly when I cut them, but they just naturally fall so that they overlap once it was in place.
jolshefsky1 year ago
Great! What's the efficiency gain? I assume you have an average power usage (e.g. total energy over 12 months) and have started measuring with the plastic in place. Keep us posted!
JacobAziza (author)  jolshefsky1 year ago
Don't know yet, I just did it a couple days ago.

But my energy use has been dropping, as I keep finding new ways to save energy, so a average over 12 months wouldn't be helpful.

Jan-255kWh
Feb-205kWh
...
Aug-194kWh
Sep-76kWh
Oct-64kWh
Nov-59kWh

This is the only change this month, so in another month or two, I'll have an answer as to whether it was measurable or not.
menahunie1 year ago
So then just don't stand there with the door open deciding what you want; know already get in and then get out.
The plastic curtain doesn't increase the frigs efficiency; only to hold air in.
That is why super markets have them due to clients always opening or entering the frig all the time.
JacobAziza (author)  menahunie1 year ago
Well obviously, but you can't always control the behavior of everyone in your household.
Even in these comments you can see that is a common problem
pinhole1 year ago
You can improve your fridge's efficiency by 20-30% by adding a fan to cool the compressor, which is usually located behind the fridge, The fridge is usually placed against a wall in such a way, that there is only a little space around the compressor and the cooling grid. Good venting significantly reduces the time the compressor is on.

I use an extension cord with master / slave function. The fridge is connected in the master socket. Once it starts, the slave socket is lit and starts an ordinary little 7 W table fan. Now there is ample ventilation, and the compressor runs about 20% less often. Negative side effect is, that you must vacum more frequently.

On the other hand, you might ask "Warum einfach, wenn man es auch schön kompliziert machen kann?" and build the electronics your self and use 8" computer of industrial fans. 8-)
JacobAziza (author)  pinhole1 year ago
The cabinets my fridge goes into actually draws air from outside, and then vents it directly to the roof.
In the winter this means that the air past the coils is cold, and in summer it means the heat from the fridge isn't heating up the house.
I have solar powered fan mounted just above the coils to encourage air flow past them.

I just figured a $2 10min project would be more likely to be implemented than a kitchen remodel
Good reflection... Another thing is that the condenser coils are going to be covered with dirt and grease more easily. But cleaning them is necessary to resore their heat transfer efficiency anyway. Could you give us some data on energy conservation with your additional fan? (it uses a little bit of additional energy, but appears as a very good improvement since natural convection cooling of the coils is not the best. Cheers, Amclaussen, Mexico City.
HowardC1 year ago
I can tell you why they all disappeared, and why this isn't a standard option on household fridges.

1. The plastic is ugly and deters visability of the products. This isn't as much of a big deal at home but still. Even if you used totally clear plastic for your project, refraction and glare would hinder visability.

2. It's unsanitary. Plastic sheeting is quite cumbersome to clean.

3. It's akward to pull things out. This is even more true at home considering you'll often have open containers. Having open containers slide out of the slits would also contribute to number 2.

4. There are much better ways to keep cold air in, such as a horizontal freezer or, a door.

Number 4 is the main thing. You don't really lose an extreme amount of cold air when you open a fridge unless you are one of those idigits that stands with the door open for 15 minutes. People think the air rapidly escapes like the air in a tire, but the difference is the air is uncompressed. Cold air naturally falls, your fridge has a bottom... hardly any of it "rolls out" as you would think it does.

Commercial stores wized up to this and switched to either glass door vertical refrigerators, or horizontal freezers. The horizontal freezers are particularly effecient. Think about it for a sec.... cold air falls, so it'll stay trapped in the walls of the freezer. Warm air rises, so it will naturally stay away from the pocket of cold air, thus keeping the freezer from doing a lot of work, it merely has to maintain that pocket of cold air.

I applaud your efforts, I genuinely do, but I'm almost positive that your modification would have no impact on your energy bill. You mentioned it only having to save you a dollar or two a year, I think we are actually in the pennies department.

If you do want to save energy, do like some of the others have suggested and put some bottles of water in your fridge. Water is a better insulator than air and because the water in the bottles isn't going anywhere, there is zero leakage. For freezers, ice is even better. Remember, prior to electricity, people kept their food preserved using only cold water (spring houses) and ice (ice boxes).
JacobAziza (author)  HowardC1 year ago
"This is even more true at home considering you'll often have open containers"
Its best to NOT have open containers, as the moisture sublimates out and then collects on the cooling fins, lowering their heat transfer capacity until the next defrost cycle (which may have to be sooner because of it)

I think the single biggest factor for stores was #1. That's just how business works.

People think the air rapidly escapes like the air in a tire, but the difference is the air is uncompressed. Cold air naturally falls, your fridge has a bottom... hardly any of it "rolls out" as you would think it does.
"If the temp and humidity are right in your house, you can pretty much see just how fast it rolls out from the freezer. Its actually a lot faster than I would have expected. You can also get an idea of how much air transfer occurred from how much suction is generated after opening the door, then closing it, and then trying to open it again.


"do like some of the others have suggested and put some bottles of water in your fridge. "
Actually, that was me, the author, that first suggested that here in the comment threads!
wolfkeeper1 year ago
Cute, but I'm not sure it makes a tremendous difference.

I read something somewhere where somebody had turned their refrigerator on its back so that the cold air didn't fall out every time you open the door.

Thing is though, he had an energy meter on the fridge, and discovered that it made no detectable difference to his energy use.

He said he thought that the air's heat capacity wasn't particularly big, and so you didn't really gain that much heat.

Haven't tried it myself.
JacobAziza (author)  wolfkeeper1 year ago
You should never turn a fridge on it's side. The cooling coils, the compressor, and the reservoir are designed to be vertical, in order to keep the refrigerant fluid in the right place and the right state (liquid or gas). If you even temporarily turn it on its side (as in for transport) it should remain unplugged for 8-24hours to give the fluid time to settle. Running it on its side will permanently damage it.

It is very possible that this is a big part of why he didn't see any gains.

Aside from that, the heat lost to opening the door depends on how often and how long the fridge is opened, how cold it is inside, how hot it is outside, and how much stuff (esp. water filled stuff, like beverages or fruit) is in the fridge. If all the space is filled with high water content things, they maintain their cold when the air flows out. If the fridge has a lot of empty space, most of the cold leaves with the air.
Speaking of which, if you have a fridge which usally isn't totally full, its a good idea to put some (closed) containers of water in their. It will make the compressor run less often, which both saves energy and increases its life span.
Thanks for the water tip. Would the same concept hold true if one wanted to store heat in the south-facing wall of an out-building, for example, then expect a temperature improvement inside the building at night?
JacobAziza (author)  mizar51 year ago
Yes, using water as a heat sink / thermal mass works anywhere.
Hey--I was going to make the suggestion of filling up the back part of the fridge with jugs of water... for this reason. But, I guess you beat me to it. I'm a little hesitant to do the plastic sheeting though, because it seems like it would make it difficulty to find stuff, and also because it seems like it would make it harder for cool air to flow into hot spots when the fridge is closed.
Yes, he or she had had to turn the compressor around to do this.

What I'm saying is, that unless you've measured it, you don't know how much money you've saved, and how worth it, it really is.
JacobAziza (author)  wolfkeeper1 year ago
That's true, however, it cost me nothing, so it can't not be worth it.

I'd measure it, but, I can't find the kill-a-watt I borrowed (from Gregg-a-Watt, an admin on this very website!).

In any event, if it only saved $2 a year, anyone who bought plastic would break even in a year, and it would be all savings after that.
I can't say if this particular instructable makes a measurable difference or not, but many people swear by chest freezer conversions for refrigeration. One of the claimed benefits is that cold air sinks, so you have less temperature gain when opening the door. Conceptually, that aspect is similar to this instructable, though there are other ways a conversion is more efficient.

You can find several articles online if you look around (like this: http://www.mtbest.net/chest_fridge_1.pdf) and some even have power consumption measurements showing that it is very efficient.
While this certainly can't hurt, I don't believe it's worth the effort. Have you actually noticed any change in your power bill? Air has a very low thermal mass compared to food. Your refrigerator door is closed 99% of the day. Preventing a few grams of cold air from spilling out the other 1% of the time will not reflect on your power bill.

A more effective and easier way to passively improve the efficiency of your refrigerator is simply to keep it full of cold food. If you have lots of spare space then you can fill the space with bottled water. Water bottles also help keep the refrigerator cooler longer in case the power goes out. Actually, keeping the freezer full of ice is even better because of the extra energy needed to convert liquid water to ice and back again (see "enthalpy of fusion").

It's possible you have a refrigerator with a very dumb thermostat which causes the compressor to start and stop too often. That will greatly reduce efficiency. The reason your refrigerator's compressor starts so soon after you open the door is because most refrigerator thermostats measure the temperature of the air in the cabinet. This changes very quickly when you open the door, but again, this represents very little lost energy. In other words, if your refrigerator clicks on soon after you open the door then it is overreacting. The thermostats in some refrigerators are smarter about this than others; they incorporate some hysteresis logic or add physical thermal dampening to the temperature sensor (instead of measuring the temperature of the air, they measure the temperature of a surface with in the refrigerator that has a significant thermal mass).
gilliana1 year ago
Great stuff - I hope the errant kill-a-watt shows up so you can get some readings on power usage with and without the plastic strips!
A minimum-maximum thermometer (some examples on this site http://www.partshelf.com/refrigerator-freezer-thermometers.html ) could help track any effect on temperatures inside the fridge, especially things stored on the door shelves.
About cleaning - if you used a clear plastic shower curtain for this and attached the strips in a way so you could take them on and off, you could wash them in the washing machine - I'd use a warm water and regular laundry detergent with vinegar as a rinse agent.
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