Make your old fridge green by insulating it

50% energysavings through insulation of my old fridge with polysterene foam

Deutsche Version: Kühlschrank dämmen

Don't throw your old fridge, insulate your fridge!

model: old fridge Siemens KT 15N00/05, bought in 1993
material cost for the fridge insulation / decor foil: 25 Euros
cost reduction by energy savings after insulating the old fridge per year: 27 Euros (119kWh x 0,23 Euro/kWh)

Measuring the baseline power consumption for at least 24 hours at a given room temperature before insulating the old fridge. Extrapolating the result for a years energy consumption. In my case the old fridge took 247kWh per year at 22°C.
Insulating the old fridge and making it eco. Important: The condenser (see how a fridge is built) must not be insulated as the air has to circulate freely around the condenser and around the fridge itself. Everywhere else i put insulation either on the outside or inside fridge wall depending on what seemed more reasonable. I used foamed polysterene for fridge insulation. Outside the fridge insulation: both sidewalls with 2cm thick polysterene and the fridge's door with 1cm only. Inside fridge insulation: back (4cm thick), ceiling and some additional polysterene insulation at a small part next to the evaporator. The polysterene / styrofoam insulation was fixed by glue. The fridge's unused vegetable cooler was replaced by a removable thick self-made polysterene box. Furthermore, I disassembled the workplate of the fridge which was just empty, insulated it with foamed polysterene too and put the workplate back on top of the old fridge.
Decorating the insulated eco-refrigerator: Covering the outer polysterene insulation first with a layer of thick foil to make the surface smooth. After that adding self-adhesive films. Covering polysterene box bottom inside the fridge with a white easy-to-wash plastic board. Separating air-circulation between the upper and the lower level in the new eco fridge by putting an equal plastic board on the grid in the middel of the fridge. That creates a cold upper part and a little bit warmer lower part of the fridge (given that the fridge's evaporator is in the upper part) and adds to the ecological effect through energy savings.
Measuring the temperature inside the self-made eco fridge. In my case the temperature inside the refrigerator was around zero degrees of Celsius though I did turn down the fridge's thermostat as much as possible. I guess that was an effect of the new insulation. So far the fridge's power consumption was down to 180kWh per year. I could not get more energy savings with further insulation, instead the temperature dropped below zero. That meant that i needed to adjust the thermostat to the new efficient insulation. I opened the cover of the thermostat and did turn the adjusting screw anti-clockwise until I got around 6-8°C in the upper level of my green eco fridge.
Miscellaneous: I did some measurements which each in itself might not do much, still i might mention them here: Increasing the distance between the self-made eco fridge and condenser with thick discs under the screws that fix the condenser to the refrigerator. Cleaning the fridge's condenser. Checking the rubber seal insulation of the door: in a dark room, putting a switched-on torch into the eco fridge, closing door and checking for light coming through the rubber seal. If so the fridge's insulation is gone and one should change the rubber seal. I did not need to do so which means it did not add to my insulating costs. Removing the grid at the top of the fridge's back for better air-circulation. This part of the self-made eco fridge is not visible anyway cause it disappears under the workplate of the kitchen. Removing some bars of the fridge's front grid at the bottom for better air-circulation too. Circulation around the fridge should be good, cause the fridge's condenser needs to get rid off the heat. So keep distance on the side and back and top of the fridge.
Measuring the eco fridge's power consumption after adding all the insulation for at least 24 hours at a given room temperature. Temperature was now 18°C in my kitchen. At that temperature I did measure and extrapolate 105kWh energy consumption per year for my self-made eco fridge. Assuming that the eco fridge needs 5% more energy with every degree of higher room temperature I calculated 128kWh at 22°C room temperature. That is a low level of energy consumption for a fridge and equals energy label A+. That means the self-made eco fridge does save 119kWh per year just by adding insulation to the old refrigerator!
Sideeffects of insulating the old fridge: Less noise, cause compressor is running less often. Sustainability and environmental benefits. Saving energy and money: I dont count the working time because it was a pleasure to work on this project. After one year the cost for insulation will be paid back by energy savings. Every year that follows i save 27Euros with my self-made green eco fridge. If i would have bought a new green ecological A++ fridge same size and quality for 350Euros the money would have been paid back by energy savings only after 7 years and 9 months (A years power consumption at 25°C room temperature: 286kWh old fridge - 90kWh new eco fridge = 196kWh x 0,23 Euro/kWh price/kWh = 45Euros/year savings. Take 350Euro for the new fridge divided by 45 Euro/year = 7,75 years.

In case you plan to make your old fridge green by insulating it yourself: thoughts about fridge insulation

Here you find the follow-up after 1 year: One year check-up

Insulated energy saving eco fridge
outside insulation: door, sides and top

polysterene insulation inside the self-made eco fridge:
backwall, top and styrofoam-box at the bottom

insulated eco fridge and green friends saving energy happily together

1 year after insulating the old fridge: a check-up

Deutsche Version: Kühlschrank dämmen

One year is gone since i insulated my old fridge. The sceptic did first not believe that it makes a difference in power consumption. When i did prove that it does a lot of difference by measuring the power consumption before and after adding insulation they argued that my kitchen will burn down, condense water will accumulate and power consumption will rise again. I take these arguments very serious.

That is why i did a thourough check-up one year after insulating the refrigerator:

Power conumption: I did meaure the energy consumption over 24 hours again. This time the room temperature was 25 °C, which is perfect because it meets the conditions for the measurements for the european energy level. Except that in my case the fridge was used normally, we put warm things inside and did open the door maybei 15 times in these 24 hours. The consumption calculated for a whole year was 135kWh which would translate into A++ fridge, except that my self-insulated fridge had a disadvantage because of warm things put inside and opening of the door from time to time. Compared to one year ago when the fridge was freshly insulated there is no difference in power consumption.

Condense water: To keep it short i could not find any. I was watching with a torch under the fridge, behind the fridge, under the styrofoam plates as far as i could see and under the decor foil at a corner where it was torn a bit. All that was dry.

Burning: The fridge did not burn down or almost burn down ;).

The look: Visiting friends get their beer from the eco fridge and they do not notice that it is modified.

So i am happy with my fridge insulating project.

Burning down the house with my styrofoam insulated old fridge?

From time to time i got questions about the safety of the styrofoam insulation around my old fridge. Indeed there were incidents of burning styrofoam insulated walls of buildings. Here they caused great troubles because they were dropping liquid burning pieces and became impossible to cross.
However styrofoam at an old fridge is different cause nobody needs to cross it in the case of fire. Styrofoam itself is not prone to take fire. It needs at least 350°C to make it burn. Of course burning styrofoam does produce toxic gases as does other materials too - even wood does. That means in case of a fire in your flat too big to extinct immediately you should leave your flat alone. Even if you have to leave behind your nice insulate-your-refrigerator-project ;)

Of course when insulating your old fridge you should use your common sense and leave all elelctric devices uncovered. You will find more details here: Insulate your fridge yourself

Modify your old fridge and buildt your own eco fridge

If anybody plans to insulate his old or even new fridge to save some energy and money here are some thoughts:

Condenser and evaporator of the fridge have to stay clear and not covered by insulation! One has to find out where they are (see How a fridge is built). The condenser is giving away the heat so it has to be on the fridge's outside, often its at the back of the fridge. But careful: some fridges got it integrated into the sidewalls, you would be able to feel it, cause while the compressor is running its getting warm. The fridge's evaporator is inside. At older fridges they are often visible like in my fridge at the upper right corner. Modern fridges can make it more difficult, cause they often integrate it into an inner wall. That is where the cold is coming from. Dont insulate that part of the fridge.
Effort. My eco fridge insulation project took the effort of maybe 20 hours, cause it became like a challenge for me to save even more energy by insulating a bit more here and there on the old fridge. But the biggest amount of energy saving was done with the insulation of the fridge's outer sidewalls and top and the fridge's inner backwall. All that was fast done and it does need no decorative measurements cause its not visible anyway.
Condense water. Theoretically condense water could accumulate under the polysterene insulation of the new eco fridge. But so far it did not. I believe that the original fridge walls dont get cold enough for condense water to accumulate. To be sure i was putting the glue on all the edges of the styrofoam so no air can get between them and the fridge itself.
Hygiene. Fridge surfaces should be easy to clean. Styrofoam itself is often s not easy to clean because of its rugged surface. A solution could be to buy insulation material with a smooth surface that can be washed or use that decorative foil i die use (see Insulating fridge)
Alternative methods to fix the insulation. Because my eco fridge is made of an old fridge and there is no warranty anymore i did glue the insulation polysterene directly to the fridge's wall. If you want to keep your fridge's warranty rights or for transport reasons it might be useful to be able to remove the insulation from the fridge. I did hear about using magnets inside the polysterene or building a frame around the old fridge which keeps the insulation at place. What i dont know is whether in these case condense water would develop between fride and insulation.
Ventilator. One could use a ventilator to get the heat away from the fridge'scondenser. It could be running at the same time as the compressor. I got the feeling that this does not save much energy.

Changing a freezer into a super eco fridge

Even the most ecological fridges (A++) on the market are only reaching 90kWh per year power consumption. That is not enough for a fridge in my opinion knowing that some ecological energy efficient freezers with minus 18°C inside only need 130kWh per year. I am dreaming of the following project: putting a fridge's thermostat into one of these well insulated energy efficient eco freezers and therewith building my super green eco fridge. I calculated that the fridge's power consumption would be around 30-40kWh per year at 25°C room temperature.

Now i found somebody describing the changing of a chest freezer into a super eco chest fridge reaching 36,5kWh a year: http://mtbest.net/chest_fridge.html

How a fridge is built

technical configuration of a fridge

A: outside the fridge
B: inside the fridge
I: fridge's insulation

1: Condenser
2: Expansion valve
3: Evaporator
4: Compressor

And the insulation is the part of the fridge where one can add some. Here are the steps i took: Insulating the fridge