In the mid to late 1960s, manufacturers of refrigerators and freezers began replacing the glass-fibre insulation used on the walls and doors of their products with polyurethane plastic foam. The move not only provided consumers with a larger interior that offered the same insulation properties (i.e. 80 to 90 mm of glass insulation is replaced by 40 mm of polyurethane foam), but lifecycle analysis performed on the two types of appliances showed that it also cut down dramatically on energy consumption and greenhouse gas emissions.

Canadian plastics body EPIC reports that the analysis took into consideration the amount of energy used and the greenhouse gases emitted during the production of each insulating material and the energy and greenhouse gases consumed and produced in the operation of the respectively insulated refrigerators and freezers. Comparisons were made on a 19-cubic foot refrigerator and a 15-cubic foot chest freezer - both with an estimated lifetime of 19 years.

Results from this life cycle analysis show that the refrigerator with the polyurethane foam consumed 39 per cent less total energy through its production and use than the one with the glass insulation. Total emissions compared over the operating lifetimes of the refrigerators found that the polyurethane-insulated one emitted 35 per cent fewer carbon dioxide equivalents.

On a larger scale, statistics show that the decision to use polyurethane foam instead of glass insulation in the 106 million refrigerators that were in operation in the United States in 1995 reduced greenhouse gas emissions by 34.9 million tons of carbon dioxide equivalents and provided an annual energy savings of almost 50 million kilowatt hours.

EPIC reports that the findings were similar with the comparison of freezers. The one with the polyurethane insulation was found to use 39 per cent less total energy than its counterpart and to emit 33 per cent fewer carbon dioxide equivalents of greenhouse gases. The 33.4 million current household freezers in the United States collectively save 9,619 million kilowatts of energy and 6.4 million tons of carbon dioxide equivalents - thanks to the use of polyurethane foam rather than glass-fibre insulation.