• Ask the Green Architect:

    Retiring Your Refrigerator,

    Earthen Floors

    Eric Corey Freed
    Green architect Eric Corey Freed answers your questions on sustainable building performance, materials, and design.


    Instead of operating a refrigerator during the cold months is there a way to harness the cold outside air to keep the food cold?

    The U.S. Department of Energy (DOE) says that every appliance has two price tags: a purchasing price and an operating cost. In any home, the refrigerator is typically the largest consumer of electricity. The idea of using the cold air outside makes so much sense; one has to ask why it is not done.

    Well, actually, it was done for centuries in the form of root cellars. Root cellars are nature's way of storing fruits and vegetables, acting as ideal storage areas for anything you wish to keep cool. Typically used for vegetables (roots like potatoes), but also for meat, milk and fruit.

    Although root cellars do not get as cold as a refrigerator during summer months, root cellars generally are 30 to 40 degrees F cooler from daytime summer temperatures. Similar to the principles of a wine cellar, the mass of the earth maintains a cooler temperature below ground. An insulated door covers a 6' by 10' hole in the ground, with stairs down to the storage.

    It is also worth noting the wonderfully energy efficient units from
    SunFrost. Sun Frost makes the world's most energy efficient domestic refrigerators and freezers. The efficiency of their refrigerators make them ideal for use with solar power, or anywhere you are generating your own power.

    If the SunFrost seems out of your range, at least consider an Energy Star-rated appliance to save as much energy as possible. A new refrigerator with an EnergyStar label will save between $35 and $70 a year.

    The reason refrigerators are such energy hogs is mostly due to inefficiency. Look at this great article listing numerous ways to reduce your existing fridge's energy use. Here is a sampling of some good practices:

    Operation Practices:

    • Minimize frequency/duration of open door
    • Check the door gasket
    • Don't overload the refrigerator
    • Correctly set the dial thermostat
    • Re-examine refrigerator's contents weekly
    • Evaluate the refrigerator's size
    • Maintain clearance around refrigerator
    • Design alcoves properly
    • Consider alternative refrigerator sites
    Design Changes:
    • Trade in frost-free units
    • Insulate the refrigerator
    • Re-locate the HDC (heat-dissipating coils)
    • Build a hybrid refrigerator/water heater
    • Use a horizontal refrigerator
    I'm considering an earthen floor with radiant heating, in a new strawbale house. Have you installed these, and seen that they last and don't crack (much) over the years? I'd like to know if it's a good, long-term investment, especially with the radiant heat.

    Technically, a true modern day earthen floor comes in various mixtures. Some are a mix of cement and earth (as in rammed earth construction). The earth chosen makes a large difference in the durability. For instance, the more clay content, the more susceptible it is to cracking from changes in water content (the clay expands and contracts quite a bit).

    If you are purchasing commercial grade soils for this floor, you can select a "plasticity index" but most single family houses just collect soil leftover from the excavation for the house. The correct soil will stabilize and prevent cracking, but there are no guarantees.

    Be sure to seal the floor when complete. The best sealer I have found is simply boiled linseed oil, thinned with turpentine and brushed on in several coats. (The odor will be gone in a week.)

    This system is the perfect complement for radiant heat. The thermal mass of the earth will store up the heat and maintain a nice, consistent temperature all winter long. You could also use the same system for radiant cooling, by running cool water through the same tubes.

    Further Reading:

    Pacific Domes -- Earthen (Cob) Floors

    Green Buildings Materials Guide -- Earthen Flooring

    Cob & Earth Building

    Alternative Construction: Contemporary Natural Building Methods

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