By sucking 55-degree heat out of the ground and concentrating it, the heat pump is able to deliver 110-degree heat into the warm air ducts of a central heating system.

FORBES: Underground Cash

It passes by a heat pump, which is in effect an air conditioner run in reverse.

FORBES: Magazine Article

The report by AEA technology said emissions of the gases, used in refrigeration, air-conditioning and heat pump systems, were "relatively small" at 3.9% of the total but were increasing.

BBC: Guernsey greenhouse gas decrease continues

Every second, the world's smokestacks and cars pump 2.4 million pounds of the heat-trapping gas into the air.

NPR: Experts: CO2 Record Illustrates 'Scary' Trend

Highlights of the new software include System Match technology with features such as True Radiant and Heat Pump Balance geared to help high-efficiency, non-conventional (i.e. not forced air) heating systems perform even more efficiently.

FORBES: World's Smartest Thermostat Is Now Even Smarter

Air is injected into the bubble rows by a squeaky pneumatic pump, then the sheets are heat-sealed on one edge.

FORBES: Magazine Article