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.

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Among the energy-saving options, two promising technology switches are the electrification of transportation (electric vehicles can be about four times as energy-efficient as standard fossil-fuel vehicles) and the use of electric-powered heat pumps to deliver winter heating and hot water (heat pumps can be four times as energy-efficient as standard heaters).

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Mr Green also said that prospective buildings should be well insulated to reduce the "heat load", the amount of heat the system needed to deliver in order to warm the property.

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The result is that too many poor countries have failed to deliver adequate power to their industries, or heat and light to their citizens.

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