Ecomodding my fridge
 

Ever since I read this article:

DIY, Super-Efficient Fridge Uses .1 kWh a Day | EcoRenovator.org

I've realised my 1KWh/day fridge is much less efficient than it should be. Unfortunately, the above super-efficient setup wouldn't work for me. I would need to find room for a second chest freezer for frozen foods.

The converted chest fridge is set to ~5°C, while I set mine to 1°C to keep wasted food to a minimum. His fridge in my house in the summer would use 0.2KWh/day due to the difference between our ambient and set temperatures. Add in a standalone freezer, and I'd be looking at around 0.6KWh/day. So my fridge/freezer isn't as hopeless as it appears. I need to find a 40% reduction in energy consumption to match his performance, not the 90% reduction that it looks like at first glance.

Door opening losses supposedly account for 7% of heat loss from a typical fridge, so switching from an upright to a chest fridge seems like a poor compromise between efficiency and convenience. I tried some window shrink wrap as a curtain to keep cold air in on the lowest shelf, but it's far too lightweight, crinkly, and annoying. It blows around every time you open the door. I bought a clear vinyl shower curtain at the dollar store, and I've hung it up to outgas and unwrinkle itself. Hopefully, it'll be ready to install next week.

The greatest room for improvement is insulation. Some folks say you can't insulate a fridge. But you can insulate the sides and top of any upright fridge, which accounts for half of its surface area. I currently have a sheet of 2" thick polystyrene insulation on top of my freezer. A thermal probe between the insulation and freezer confirms that it's holding heat in better now.

The back of my fridge has no vents or coils, and is cool to the touch. It sounds like insulating that is fair game, too.

I can't have bare insulation in the kitchen. Fiberglass presents a health concern, exposed polystyrene is a fire hazard in a room with so many ignition sources, and cotton would get filthy. I'd have to build a cabinet to mostly enclose the fridge, probably out of thin plywood. It would have to be built very precisely to keep air from infiltrating between the insulation and the fridge.

I suspected that since the compressor and condenser are on the bottom, heat enters through the bottom of the fridge compartment. A probe below the vegetables drawer under a kitchen towel reads 17°C (versus 10°C elsewhere in the fridge), and confirms that I need more insulation there.

I'd like to replace the fruit and vegetables drawers with fiberglass batting, but I'm not sure if it's okay to keep fiberglass in the fridge. Cotton batting (or corrugated kitchen towels) would be ideal, if only it was locally available and affordable. I've got an old wool blanket in there for now (the same one as my A/C seat cover is made from), but what if I spill some milk or beef juice in the fridge?

I'm open to suggestions. How can I keep insulation in the fridge clean? Does the insulation cabinet sound easy enough to build? Any thoughts on what to do with the door of the fridge?

If you are using styrofoam, you'd want to use epoxy resin with fiberglass, which is not a health hazard unless you get to allergy levels. A sheet of Arborite or other countertop laminate is probably easier to get a good finish with, though. Coroplast would be easy, funky, and let you use thumb tacks instead of 'fridge magnets. Inside, the same material recommendations apply. A nice bead of caulking will make up for very casual joinry.

Or, how about gutting a bigger fridge, and slipping the shell over yours? Find your condenser, and its air supply, which should be left unobstructed, but it sounds like they may all be on the bottom, so you can do the back as well.

There was an article in Home Power magazine many years ago (late '90's?) about insulating the fridge and building a cabinet arount it. IIRC it was good for a 5%-10% energy reduction.

I can understand not wanting bare, toxic insulation in the kitchen, but what about cork? I read that it's a good insulator, has a nice look, and you can use thumbtacks, as BicycleBob suggested. Just remember that metal thumbtacks are like little heat bridges...

The door can also have a piece of insulation glued to it, but make sure you have enough clearance to open it. I wonder how much heat is lost (gained) through the magnetic skirt around the door's perimeter, and how one would go about improving on that.

If you insulate the back of the fridge, then remember to leave room for free airflow from the compressor.

If there is enough space between the bottom of the fridge and the condenser/compressor you can add insulation there. Maybe a 5mm piece of styrofoam with aluminum foil on one side? Or just alu foil if there isn't enough room.

I've read about keeping large empty containers in the refrigerator to reduce the volume of air that escapes each time the door is opened. If they are filled with water, then the increased thermal mass helps keep the temperature low during a power outage.

Except on the hinge side, it is easy to add insulation all around the door seal. Fuzzy mating surfaces may be optimum, but hard to clean. Hard-coated foam parts can be progressively glued in place to give virtually zero air space where the insulation parts. You can also use door weatherstripping material, and a mechanical door latch. Along the hinge edge, you can extend the hinges, or use flexible insulation.

On a similar vein, my wife stuffs the freezer with bread after the shopping. Thermal mass helps keep down open door losses. Although the freezer is mostly closed and it has drawers. So the theory is sound only it would apply to fridges more.

Re: the fridge compressor. It produces a lot of heat down there and it has to have a negative effect on fridge temps. Perhaps installing reflective insulation above that would reduce heat rising into the underside of the fridge?

ollie

In my old house I had some styrofoam board behind the fridge. I don't think it's that much of a fire hazard. It's not readily ignitable like gasoline.

For the cotton insulation, can you placed it in a larger freezer bag to keep it clean?

I saw a solar decathlon show a couple years ago and the competitors were really worried about door opening time. They made a list of what they wanted to get out of the fridge, then quickly opened it, grabbed the food, and slammed the door. I don't get that crazy, but I do try to minimize door open time.

My current fridge has the coil under it towards the rear by the compressor. A small fan draws air through a vent in the toe kick, blows it over the coil, then exhausts it back out the front. I'm sure this is not optimum as the cooler intake air is mixing with the warm exhaust air. There must be a better way to do this. This is an energy star fridge, though. If your fridge is designed like this, you should be able to add insulation to the sides, back and top without affecting its operation.

My Mom's refrigerator is also like that. When I stand in front of it, I can feel the warm breeze on my toes. I seems like the whole fridge is bathed in rising warm air. I imagine that when the door is open, cold air drops out while warm air from underneath climbs inside. No wonder her fridge is on more often than off.
So how about adding a duct to lead the warm air far away from the fridge (or maybe behind/above it)? That way the temperature of the whole area may drop by 1-2 degrees.

The design with condensers (=hottest part) placed underneath is not efficient. The "old fashioned" ice boxes with large coils on the back wall were much better. Granted, they used more energy, but this was because of poor insulation. The large surface area of the coils was much more efficient at transfering heat, and the placement allowed the natural convection of airflow, so no energy hogging fan was needed.

My superefficient refrigerator uses only 0.7kWh/day, and it has rear placed coils. Even when it's been on for 15 minutes those coils are barely warm. I wonder if having the freezer below the fridge helps or hurts efficiency?

How about putting your fridge on a timer. Recalling all of my hurricane training, I remember that a fridge can remain without power for about three days without spoiling the food inside with quick access to what you need.

I would suggest setting up a timer that would shut off power to the fridge after a certain time, like after dinner and kick on again before breakfast or later depending on when you first use it in the morning.

It may just save you a couple cycles a day or more depending on your fridge.

I think the prettiest option is to have it match the walls or cabinets in the kitchen.

Cork has many nice properties, but I was thinking of adding four inches of insulation to each side of the fridge, at which point cork becomes cost-prohibitive. I'm leaning towards fiberglass batting, as it has the most thermal resistance for the dollar. Can I buy cellulose batting locally?

@Ollie: adding loaves of thermal mass helps reduce door opening losses by reducing the volume of air that can escape during each door opening event. Adding thermal mass doesn't affect the amount of energy that escapes when the door opens: empty water jugs should work just as well as full.

But full water jugs would reduce the number of times during the day it cycles on and off, which could save a little power. Also, the water jugs can be set outside to freeze in the winter, and brought into the fridge to thaw.

Piwoslaw, you have an interesting fridge. I wonder, how much insulation does it have? My fridge's sidewalls including the steel outer and plastic inner shells are 4cm for the fridge, 5.5cm for the freezer.

Another thing I noticed is when my fridge turns on, it draws 680W / 6A, and the voltage at the KaW drops from 121V to 117V. Am I losing an additional 3% through i²R losses between my breaker box and the outlet in the kitchen? The house dates to 1929, and I have no idea how old the wiring is.

AFAIK they don't make cellulose batting. Its all loose blown.

Rigid foam would be more expensive, but would give you a higher R-value per inch.

I'm quite interested to see how this turns out.

Biggest thing one can do is remember to clean the coils regularly.

I have a fridge like the one described in the article. It is a cheap chest freezer with this temperature controller added. I did not buy it to save energy, it was used for kegs of beer back when I was homebrewing. This type of chest freezer/temp controller is very common with homebrewers to allow fermentation to occur at exactly the right temperature. And to serve beer at exactly the right temperature.

I would use this type of chest freezer fridge again. It is far less expensive to purchase a cheap chest freezer plus a controller than a stand up fridge. And then your electric bills are lower as well.

If you were modding a chest freezer the way you plan to mod your stand up fridge, the chest freezer would just get that much more efficient. However instead of 0.1 kWh/day it might draw 0.08 kWh/day.

I never checked the amp draw on my chest freezer fridge.

The best advice I can give is to keep your fridge filled with beer.

My refrigerator is an ARDO, model CO 2210SHX. Volume is 218 liters (7.7 cu.ft.) for the fridge and 83l (2.9cu.ft.) for the freezer. The refrigerator part's walls are 4.5cm thick, freezer 7.5cm, while the doors are 6.5cm and 9cm thick, respectively. It has a scroll type compressor which uses about 65W when on. No fans, no automatic defrost. We bought it in late 2007, today it costs the equivalent of $520, but is well worth every cent.

Food for thought: Refrigerator Insulation - EcoRenovator

I would be disappointed with a 17% decrease in energy consumption. I can more than double insulation thickness across everything but the door, so I would hope to see a ~50% drop in energy consumption.

My fridge breathes in through the front and out through the back, so I'll have to leave the vent unobstructed, but I can insulate most of the back.

I can get R19 in fiberglass for $25-35. R20 in Polystyrene would be $170.

I was thinking about framing a 6' tall studwall in 2x4 and finishing it with 0.25" drywall and paint, but I'd probably be better served by building a freestanding plywood box around the fridge. Given the dimensions of my fridge (28"x26" plus a 4" thick enclosure), I can use two batts of 15" wide insulation on each side, and I'd only have to cut one batt lengthwise.

I would build the right and rear walls, insulate them, slide the fridge in, then install the left wall (the pretty one) and the top.

Now, how do I get three 4'x8's home in the Insight? I think I'll screw them together, then attach a caster and a handle and walk them home - 1.3mi. I'll just have to wait for a day without much wind.

Wait for a windy day and put on your rollerblades...

If your required width is low enough, have them cut the plywood at the home center (usually free), then load all the pieces in the hatch.

For a walkable distance, it is easy to carry plywood on a bicycle. Lash a board to the handlebars so that it will support the sheets flat and stick out on one side enough to steer. Put most of the weight on the seat, and hold the sheets to balance and push the load. For drywall, a bit more wood for support might help.

Foam cushions (or barrow the cushions from your couch) between the insight and ply, and some lashing to keep them atop the car. for 1.3 miles you are likely not going to go fast enough for the aero penalty, nor to cause much lift.

I actually did reduce power consumption of my 19 years old fridge down to 50% by insulating it nicely and tuning the thermostat a bit. I describe all the steps i did at my homepage.

http://coolfridge.blogspot.de/


I can only encourage you to try it!
Allen

I did reduce power consumption of my old fridge down to 50% by insulating it myself. Since one year it does run flawlessly. Have a look at my page for details, measurements i took or for comments:

Make your old fridge green by insulating it

Allen

It's not for everyone, but I have been very pleased with the mod I did to the 'fridge in my apartment.
I bought a temperature controlled power switch and have it in my freezer.
I've used it like this for over a year.

Did you measure the energy savings by your measurements?
And why did not the thermostat of the fridge do that job?

Greeting. Allen

I have another thought regarding fridge efficiency.

During the summer your fridge is basically a space heater in an area you don't want heated and in many cases, use power to cool. This is horribly inefficient.

the solution is to figure out a way to vent that heat outside.

My fridge has its evaporator (or is it condensor, I always screw the two up) on its rear wall. My thought is to enclose this is an airtight box made of some sort of thin insulated board that you can buy for next to nothing at HD. Half inch thick or so should do. Use duct tape to hold the seams together and make it air tight. Place an input duct near the floor and an exhaust duct near the top. You could make these ducts out of the same material. Box out the sheet rock on an exterior wall so that when the fridge is pushed against the wall, it fits into these holes. On the outside wall, you would have to trim it out with some sort of ventilated cover.

I believe there would be sufficient airflow thanks to the natural chimney effect when the fridge is running.

During the summer, you'd get rid of that unwanted warm air. During the winter, you would be venting away wanted heat, but, the fridge itself should run quite a bit more efficiently due to the cold outside air running across the coils.

An even better solution for cold temps would be a figure out a way to pipe that cold air directly to the fridge. I actually like Pioslaw's solution of placing frozen water bottles inside. So simple it is brilliant. I will do this next winter.

Another thought I had was to figure out a way to plumb some sort of heat exchanger to use cold potable water on it's way to the water heater. There are a few potential problems such as what do you do when there is not enough hot water demand to carry away all that heat, but, there are solutions. Also, I am not sure how a fridge's coil would like being submerged in the heat transfer liquid, most likely water.

How about a chimney on the back of the fridge? - EcoRenovator.org

Why not disconnect the duct from the hole in the wall and have the warmer air help heat your kitchen?

Why pipe it? If the outdoor temp is in the right range, then just unplug the fridge, pack your stuff in a basket and put it outside. You can't get lower than using no energy.

Not frozen water, just plain liquid water. Only add thermal mass (and decrease the volume of unused space), no phase-change stuff. Over at EcoRenovator, Daox did an experiment with putting water jugs outside to freeze and then moving them to the fridge. Yes, it reduced the refrigerator's energy consumption slightly, but in essence it was removing heat from the house, so the heating system had to work a little harder to make up for that.

This has been done, but I'm not sure if the gains are worth the effort.

The bottom line is: A refrigerator is often thought of as a space heater. This is true, but not to the extent that most people think. The radiator coils get warm, but most of that is the kitchen's heat which permeated through the insulation into the fridge. The only extra heat comes from the energy used to run the compressor (and the lightbulbs). So if you move that heat outdoors, you generally have a heat pump, specifically an air conditioner. You are pumping your house's heat outdoors. Good during cooling season, bad otherwise.

Now, since the only new heat produced by a refrigerator comes from running the compressor, then it would be best to reduce compressor use (or get a more efficient, scroll type compressor). This can be done by adding insulation - the longer it takes a given amount of heat to seep into the fridge, the less often the compressor will be needed.

Once you have better insulation and/or added thermal mass, you can put it on a timer to keep it from turning on for longer periods, eg at night or during the day when no-one is at home. You should keep track of the temperature inside, though, to make sure nothing spoils.

Some interesting points, Pioslaw.

I think the one idea that definitely makes sense is venting the warm air outside during the warm months. Using the cold outside air to cool the coils in the winter is debatable because of its net effect on cooling the entire house. My gut feeling is that you are probably best off to just seal up the wall when it gets cold enough to run the heat. There is one problem I see with the summer mode of operation. If it is very hot outside, drawing the cooling air from outside means it will have to run more. A possible solution is to continue the chimney down through the floor so you use cooler basement air for cooling. Of course this means that the basement gets warmer.

With my fridge , 7 year old GE ,all i can do is add insulation, I am in the process of insulating it, with the insulation in the inside and some on the outside.
The bottom inside of the fridge, nearest the mini fan cooled coil pack and the compressor, will get the thickest insulating.
The plans is to tape the seams and cover the inside foam with a hard washable surface.
I am going to enhance the air flow both in and out by making defined air channels,as it mixes now.

- Here's a tip for everyone -

Yesterday i turned my hot water heater down to a comfortable temperature,for use without the need of adding cold water.
I had enough of super heating the water just to add cold water to it. :eek:

You mean like this?
http://thereifixedit.files.wordpress...-be-cooler.jpg

Two more suggestions for refrigerator efficiency:

1. Heat transfer through the walls (heat gain) is a function of temperature difference, so you can raise the inside temp slightly (sometimes fridges are set way too low) and/or lower the ambient temp. I'm not suggesting having your house's A/C works its pants off, but keeping the kitchen slightly cooler (leave a window slightly open at night with the doors closed), or moving the fridge to a cooler area. Like farther away from the stove/range, dishwasher, sunny window, or other heat sources. I once saw a refrigerator placed so that the heating system's vent was blowing hot air at it all winter, and the sun was shining on it for 1-3 hours daily, year round:eek:
2. Put a small fan under the rear coils, blowing upward whenever the compressor is on. This improves the heat exchange efficiency of the radiator, and helps the warm air leave the rear wall faster.

They started putting the condenser coils below next to the compressor ,on the newer fridges.

It has a fan that sucks cold from under one side of the fridge over the condenser coils and exhaust's directly onto the compressor, cooling it at the same time.
From that point it is forced back out the other side of the bottom.
I need to insulate between the condenser/ compressor and crisper floor. The back of the fridge where usually the condenser wrack would reside is smooth sheet metal,which stays cool, as does the top of the fridge.
When i finish with the insulation job, ill post pictures.
Tomorrow i am off to the Building material recyclers to get some thick foam insulation. I try to recycle when ever feasible.

[QUOTE=Piwoslaw;324226]You mean like this?
http://thereifixedit.files.wordpress...-be-cooler.jpg


Haha NO ! But now im thinking about it ! LOL

Back from the used/unused Building supply store.
The foam i wanted was gone. I had seen a large amount of thick foam there last time i was in. Found nothing there that was priced right, they had new 2x8 blue rigid foam insulation for $22. Not what i was hoping for so i continued down the road.
Stopped in the Habitat for Humanity Re store, a store where they sell unused and used building supplies. Mostly left overs from builds. Found some insulation but i need more, I am going to keep looking and keeping an eye out for the 2" blue rigid insulation.

Cork works well for insulation, more so if have not a lot of space to apply it to.
Sailboat owners retrofit cork onto the inside hull walls for insulation, it comes thin on 3 to 4 ft wide rolls.
Cork flooring would work excellent, its about a inch think and can be found used/ previously installed. :thumbup:

[QUOTE=Piwoslaw;324226]You mean like this?
http://thereifixedit.files.wordpress...-be-cooler.jpg

Hehe, my self-insulated fridge does not look that wild and hairy. After glueing the styrofoam which did reduce power consumption down to a half of the original baseline i added some decorative foil (details and more pics here: Make your old fridge green by insulating it)

The result looks quite like a normal fridge i would say. But judge yourself. If you look closely you can see that the door and the side are insulated.

You got me motivated to check mine. The coils were thoroughly covered with dust - it took a vacuum and then compressed air to get them clean.

I used a chest freezer/thermostat as a refrigerator for a few years. It used about 15 watts in the summer and 11 in the winter on a continuous basis (about 100 watts when running). I think the main savings was condensation, as it quickly gets to 100% humidity. Another is that the expansion coils are at the fridge temp instead of freezer temp, which should lead to a higher coefficient of performance. The top-opening door doesn't hurt, obviously. For freezing I had a fairly big chest freezer running at around 40 watts average.

I switched to a normal fridge partly due to the disadvantages (space efficiency and condensation), and partly because fridges are quite efficient these days. My old fridge of early 80's vintage used a lot of power... about 200 watts continuous, and around 700 watts when on. The chest fridge paid for itself very quickly. The new one, which is a normal no-frost top-freezer from Lowe's (not a super-efficient Sunfrost) uses 101 watts when on, and 35 watts average. I don't know why they're so dramatically different, as it's very similar other than thick doors. Thermodynamics hasn't changed in the last 30 years, but fridges sure have!

I think the best plan is to start with a modern (post-2000) fridge. A chest fridge is extremely efficient, but adding another freezer cancels it out. Robert's 680 watt draw means an older fridge and likely huge savings just for buying a newer one. The run wattage is a big deal, even if run time is up. Note that chest freezers can't be further insulated because the condensation coils are on the outside, but fan-cooled fridges don't have that limit.

Around 2000 vacuum-packed insulation (or whatever it is called) went mainstream, resulting in a much better R-value from the same thickness. Add to that more efficient (and quieter) scroll-type compressors.

They can - the coils are on 1 or 2 sides, which leaves 4-5 sides free to be insulated. Each side counts.

[B]Refidgerator is insulated[B]
 

I have finished insulating my fridge, it was a success giving a 38% improvement in efficiency/energy consumption.
I also added a rear exhaust vent for the insulated compressor / condenser area to exhaust into a hall closet, instead of the kick panel.


I used 4 layers of 'SolidBlack' wood flooring insulation and one layer of blue vapor barrier over top along with 2 cans of 3M spray adhesive .
The under fridge is completely covered from kick panel and lower sides to the back of the fridge with a 4 layer sheet of SolidBlack. You can see it sticking out at the bottom of the fridge, that will be bent upwards and put in the top of the vent.

I am currently testing 10 gallons of water in 2 liter jugs in the bottom of the fridge.
I'll post back with the gains or losses from the PCM's (water jugs) when i collect more data.

I just retired my 1968 model General Electric fridge- sad to see it go. They don't sell the new ones in Avocado Green. :( Ha- the old fridge was green after all! :rolleyes:

Got a brand new FridgidAire of about the same size- 18 cu. ft. I happened to have a scrap piece of foil-faced foam (out of the same chunk I used to make the engine blanket for the F150) that was pretty much exactly the same width and depth as the top of the fridge, so up there it went. Perhaps someday the rest of it will get more insulation too- at least along the sides and back. Unfortunately the doors have a pronounced curve to them which although not impossible, complicates adding sheet insulation to the front.

Should see a nice power savings just from having the newer tech though.

I use a dorm fridge. Because I don't keep things in the fridge that don't need to be there, such as 2 week old left-overs and ketchup.

Refrigerator mods
 

I have tried several mods on my fridge. I wrapped the compressor with water cooling coils to carry the heat outside. I put a 1.5" layer of polystyrene
on the inside floor of both the fridge and freezer. Neither of these mods showed any improvement on my "Watts up" watt meter/data logger. The one thing that works for me is to clean the dust off of the condenser coils EVERY month. I have read that even a fine layer of dust reduces the efficiency of the condenser. My fridge is energy star, but I believe it is only energy star when it leaves the factory, And that energy star does not cover real world dust removal considerations. I hope this helps. My electrical bill is $14/mo.
While my fridge is a double wide/ice maker, chilled water in the door, and I have computers, a big screen tv, outside lighting. I'm grateful to have all the modern conveniences and a reasonable electrical bill. I have converted about half of my lighting to LED and eliminated all the vampire loads. My best electricity wasting finds are: My furnace standby ignitor was sucking 15W 24/7 for the 9 months that I never used it and my internet modem was using 17 Watts 24/7. It gets turned off automatically now when I shut down my computer.