Controlling for comfort — and for cost

Resident Lisa Harrison uses a hand-held remote control to turn the heat down a few degrees, adjusting the temper­a­ture to her exact liking. The slight humming sound emanating from the Daikin unit in her dining area stops, but heat keeps flowing steadily in. 

Comfort was once elusive in Harrison’s multi-family building. Residents had to layer up or move space heaters from room to room. But with the new heat pumps they’ve had since 2020, all it takes is a touch of a button to achieve a level of comfort that was previ­ously unthinkable.

“Everyone loves having control,” said Harrison.

The co-op’s Daikin heat pump systems are made up of a series of indoor and outdoor units connected by a network of refrig­erant and elec­trical lines. The outdoor units pull air in through a large L‑shaped heat exchanger. The heat pumps then extract the thermal energy from inside the apart­ment, if they’re oper­ating as air condi­tioners in the summer — or, if they’re acting as heaters in winter, they absorb what little heat there is from the outside air and move that heat inside the building. 

While increased comfort and control are the most tangible bene­fits for resi­dents, the heat pumps also reduce energy use. As Jon Hacker, Daikin’s former Energy Efficiency Business Development Manager, put it, effi­ciency is ​“engi­neered into the system.” This is done with inverters, which use an algo­rithm to adjust the motor speed and provide cooling and heating at the minimum power consump­tion, rather than turning off the unit and then turning it back on, which makes it work harder to achieve the desired temperature.

“The lower the percentage is, the more effi­cient the system works,” Hacker said. ​“So if I could run my heat pump at 50 percent and main­tain comfort, that’s way better than running it [at] 100 percent.”

As resi­dents modu­late heat pump use, they’re also learning about how it affects their budget: Harrison found that her elec­trical bills are signif­i­cantly more expen­sive in the cold winter months than they were pre-heat pumps. In February 2020, for example, she spent $68.56 on elec­tricity, whereas the following February she spent $260.82 — about a 280 percent increase.

“Comfort does come at a cost,” Daikin’s Hacker said.

Lisa Harrison said seeing her elec­tricity bill does make her more conscious of her energy use. She has always been in the habit of keeping her heat off at night; now, with the heat pumps installed, this prac­tice can reduce energy use in the long run, according to a Taitem study. 

The study, conducted from December 2023 to April 2024, asked resi­dents to manu­ally ​“set back” the temper­a­ture a few degrees for approx­i­mately 8 hours each night. According to the prelim­i­nary results, the night­time setback reduced heating energy use by approx­i­mately 30 percent per apart­ment. Five units total participated.

“The biggest lesson is that ​‘set it and forget it’, which is often recom­mended by installers and insti­tu­tions like util­i­ties or funding sources, is out of date,” said Betsy Parrington, the vice pres­i­dent of Taitem. ​“Night setbacks save energy for heat pump systems.”

Moderating heat pump temper­a­ture is not an exact science. But gener­ally, Hacker said, best prac­tice would be a ​“moderate setback” of a couple of degrees if resi­dents plan to be away from their home for more than eight hours, and a ​“deep setback” if they’ll be gone for a longer period of time.

For curious resi­dents who want a break­down of their elec­tricity use, Con Edison ​‘Smart Meters’ in the building’s base­ment provide detailed feed­back in 15-minute inter­vals. In theory, having access to this gran­ular data combined with elec­tricity bills will offer resi­dents even more infor­ma­tion and control over their systems, and induce them to use less, Sahagian said.

“That’s one of the things that I insist on with this kind of a project, because if you don’t have that feed­back mech­a­nism, then people just leave it on all the time,” he said.