Heat pumps that fit in an apartment window could make a big impact in reducing greenhouse gas emissions that contribute to climate change. Heat pumps are a highly efficient technology that has been outshipping gas furnaces in recent years, but they have mainly been an option for owners of houses. When used in big apartment buildings, they offer the prospect of replacing systems that rely on inefficient central boilers powered by oil or gas. The New York City Housing Authority is testing the window units in Queens, where residents say they're working well. The International Energy Agency says installing heat pumps in apartment buildings and commercial areas should be a priority to help meet climate goals worldwide.
