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By Isabella O鈥橫alley and Ingrid Lobet

The Associated Press

NEW YORK 鈥� For 27 years, the heat in Regina Fred鈥檚 Queens apartment building came from a noisy steam radiator that she couldn鈥檛 control and sometimes wouldn鈥檛 turn on, leaving her shivering. Sometimes the radiators ran so hot that residents had to keep their windows open in the middle of winter for relief.

That all changed a few months ago, when Fred got a window-mounted heat pump as part of a New York City Housing Authority pilot project intended to cut energy costs and lower emissions. Now Fred can merely touch a dial to bump her temperature up or down, and she often enjoys 鈥渁 very good silence.鈥�

鈥淭hey did a demonstration for me, and I was thrilled,鈥� she said.

Fred鈥檚 grown children call the heat pump 鈥渢he best thing鈥� in her apartment, and her neighbors have knocked on her door to check out the unit.

Heat pumps, highly efficient appliances that have grown in popularity in recent years to rival gas furnaces, have mainly been an option for homeowners. But new designs are making them practical for apartments, which often rely on inefficient, centralized steam boilers powered by oil or gas. That represents a promising climate solution for buildings; their operations account for 26 percent of global energy-related carbon emissions, according to the International Energy Agency.

Installations of heat pumps in apartment buildings聽and commercial areas should 鈥渂e a priority area鈥� to maintain the growth necessary to meet national climate pledges worldwide, the IEA stated last year. The聽U.S. alone has 23 million apartment units, according to the National Multifamily Housing Council, representing a huge sector of people who could use less energy with heat pumps.

New York law requires building owners聽to make big cuts in greenhouse gas emissions over the next decades. To comply, NYCHA is targeting heating and cooling, the largest source of emissions for the agency, which houses about 528,000 people across more than 2,400 buildings 鈥� or about one in 17 New Yorkers, said Shaan Mavani, the agency鈥檚 chief asset and capital management officer.

Centralized steam boilers powered by natural gas or oil typically provide the heat, and they are wasteful 鈥� the NYCHA鈥檚 climate mitigation road map calls steam heat 鈥�19th-century technology incompatible with 21st-century needs.鈥� Mavani said between 30 percent and 80 percent of heat is lost through old and leaky infrastructure before it reaches apartments. And that doesn鈥檛 account for the waste when residents must open their windows to dissipate excess heat from a system they can鈥檛 control.

Eric Wilson, a senior research engineer for the Energy Department鈥檚 National Renewable Energy Laboratory, led a team that analyzed heat pump performance in various electric grid scenarios and found even the lowest-efficiency pump would cut greenhouse gas emissions and save on operating costs in every U.S. state. That analysis didn鈥檛 include the kind of pump being tested in Queens because it wasn鈥檛 yet on the scene, but Wilson said he would expect similar results.

Most heat pumps require ductwork, which isn鈥檛 an option for renters in a unit they don鈥檛 own. And ductless systems typically require extensive installation that includes wiring, making a hole in a wall and a sizable external compressor.

Gradient and Midea, the two companies making the units for the pilot project at Woodside House, downsized it all into something that looks a bit like a window air conditioner but with a much lower profile. Exterior and interior halves drape over a sill to leave the window mostly unobscured. Gradient鈥檚 unit can be installed in 15 minutes and plug into an ordinary wall outlet, according to the company.

The units 鈥渢ake up more space on the inside (of apartments) than (residents) might be used to,鈥� Wilson said, but Fred called hers 鈥渧ery beautiful.鈥�

鈥淟ook, I even have it for decoration,鈥� she said. Her three window units are usually topped by flowers and decorative candles. In one room on a particularly sunny day, morning light shone on a rose, a jar of rose petals, decorative boxes, and a 鈥淟OVE鈥� sign atop one of them.

Z Smith, an Eskew Dumez Ripple architect who isn鈥檛 involved in the Queens project, said such retrofitting 鈥渋s the carbon-smart way to get to better comfort for occupants.鈥� That鈥檚 because one of the most effective ways to reduce emissions by buildings is to avoid putting up new ones, which result in significant emissions due to all the new concrete, steel and wood.

He called the low-profile heat pumps a 鈥渓ightweight intervention鈥� because they鈥檙e so easy to install.

The NYCHA will evaluate results of the pilot project, with plans to eventually install more than 4,000 heat pumps over two years in the Woodside development if all goes well. The authority expects to save money on operating and maintenance costs with the heat pumps but is waiting to see initial results before it projects those savings.

Gradient was founded seven years ago in San Francisco with the ambition to decarbonize buildings with a window-mounted heat pump that can be easily installed without technicians. Part of the company鈥檚 goal was to present a solution for people just like those at Woodside, CEO Vince Romanin said 鈥� people in older multifamily buildings with complaints about their window ACs or aged radiators that don鈥檛 have a temperature setting.

鈥淲e think that if you鈥檙e not building solutions for people who need it most, if you鈥檙e not building solutions for people who have insufficient heating (and) cooling today, they鈥檙e not really solving climate change,鈥� Romanin said.

Editor鈥檚 note: O鈥橫alley reported from Philadelphia.