What They Are and How They Work: Heat pumps are combined heating and cooling systems. They work by moving heat from one space to another through a similar process to that of your refrigerator or window air conditioner: A closed loop of refrigerant combined with a compressor and an expansion valve absorb heat in one location and release it in another. This process can be used to cool a space or heat it. Importantly, because heat pumps move heat rather than combust fuel to release heat, they can be extremely energy-efficient—sometimes moving two to three times more energy than they use to operate. They also are a decarbonized source of heating or cooling, provided they run on electricity produced with renewable energy, such as wind or solar power.
Heat pumps can be classified into two large categories: air-source heat pumps and ground-source heat pumps:
Air-Source Heat Pumps: These pumps either draw heat from outside air to bring inside (in heating mode) or expel heat from indoors into outside air (in cooling mode). These systems have an outdoor unit that often contains a compressor and fan. You’ll often see these units sitting outside, mounted on exterior walls or roofs. The latest air-source heat pumps can now find heat in outdoor air even during New England’s coldest winters. If sized correctly, they can keep a whole home warm in winter and cool in summer.
Learn more about air-source heat pumps here.
Ground-Source Heat Pumps:: These heat pumps draw heat from the ground to bring inside (in heating mode) or expel heat from indoors into the ground (in cooling mode). These systems often use either wells drilled in the ground or buried pipes. Ground temperature is substantially cooler than air temperature in summer and substantially warmer than air temperature in winter, so ground-source heat pumps are some of the most energy-efficient systems available.
Learn more about ground-source heat pumps here or visit the International Ground Source Heat Pump Association (IGSHPA) website - a non-profit industry group that serves as a clearing house for educational resources, research, and publications on ground-source heat pump technologies.
Market Ready? Yes, both ground-source and air-source heat pumps are readily available for residential and commercial buildings. If you are interested in a system, we encourage you to reach out to multiple contractors to compare pricing and design options. National Grid maintains a list of contractors who have been approved to deliver heating and cooling systems through Rhode Island’s energy-efficiency programs, for example, but the list is not comprehensive.