Connect the Ice Bear to your air conditioner, and instantly cut your AC’s energy consumption by up to 20 percent. The machine freezes water in its 300-gallon storage tank at night when temperatures are low and the electricity supply is plentiful. When the AC kicks in, the Ice Bear circulates refrigerant through coils in last night’s ice (which will last well into the evening, even on a 90°F day), chilling it before it flows to the AC. This spares your AC from having to use daytime electricity to cool the refrigerant through the standard energy-intensive process. From $7,000;
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