People who rent their homes, or don’t have enough money to make major upgrades to their homes, have for many years been left out of a major shift in heating and cooling technology that can improve efficiency, save money and be better for the global climate: heat pumps.

Heating and cooling buildings consumes 35% of all the energy used in the United States each year. Many homes and businesses are converting their fossil fuel-powered heating and cooling systems to electric-powered heat pumps, which use electricity not to generate hot or cold air but to move heat into spaces needing warmth and out of spaces needing cooling.

Until recently, that process has required a significant amount of sizable and expensive equipment to be permanently installed in a building, which needs a professional contractor and can cost as much as US$10,000 just for the installation – in addition to the actual equipment. Often called mini-splits, these systems usually have a condenser outside the building that exchanges heat with the outdoor air and an evaporator inside that exchanges heat with the indoor air.

But now window heat pumps are becoming available in........

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