What is the difference between a heat pump and an air conditioner?

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1. 1

   Heat pump (Wikipedia)

   WikipediaPublished Oct 14, 2026Checked Oct 15, 2026

   “A heat pump is a device that uses mechanical or thermal energy to transfer heat from one space to another. The mechanical heat pump uses electric power to transfer heat by compression. Specifically, it transfers thermal energy by means of a heat pump and refrigeration cycle, cooling one space and warming the other. In winter, a heat pump can move heat from the cool outdoors to warm a house; in summer, it may also be designed to move heat from the house to the warmer outdoors, functioning in the same manner as an air conditioner. As it transfers rather than generates heat, it is more energy-efficient than heating by gas boiler. In a typical vapor-compression heat pump, a gaseous refrigerant is compressed so its pressure and temperature rise. When the pump operates as a heater in cold weather, the warmed gas flows to a heat exchanger in the indoor space, where some of its thermal energy is transferred to that space, causing the gas to condense into a liquid. The liquified refrigerant flows to a heat exchanger in the outdoor space, where the pressure falls, the liquid evaporates, and the temperature of the gas falls.”

2. 2

   Thermoelectric heat pump (Wikipedia)

   WikipediaPublished Oct 6, 2026Checked Oct 15, 2026

   “Thermoelectric heat pumps use the thermoelectric effect, specifically the Peltier effect, to heat or cool materials by applying an electrical current across them. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current. Such an instrument is also called a Peltier device, Peltier heat pump, solid state refrigerator, or thermoelectric cooler (TEC) and occasionally a thermoelectric battery. It can be used either for heating or for cooling, although in practice the main application is cooling since heating can be achieved with simpler devices (with Joule heating). Thermoelectric temperature control heats or cools materials by applying an electrical current across them. A typical Peltier cell absorbs heat on one side and produces heat on the other. Because of this, Peltier cells can be used for temperature control. However, the use of this effect for air conditioning on a large scale (for homes or commercial buildings) is rare due to its low efficiency and high cost relative to other options.”

3. 3

   Geothermal heat pumps and thermal energy networks: Technical feasibility and market adoption.

   iScience (Simpson et al.)Published Sep 9, 2026Checked Oct 15, 2026

   “Geothermal technologies, including geothermal heat pumps (GHPs) and thermal energy networks (TENs), are gaining traction as methods to efficiently meet heating and cooling loads. Changes to costs and incentives may impact adoption and can help support decision-making in effectively deploying GHPs and TENs. In this work, the updated distributed geothermal market demand (dGeo) model is used to analyze scenarios across the US demonstrating a range of economic potential and adoption for GHPs and TENs. We find that the more established GHP technology has widespread economic potential and adoption, while the newer TEN technology has economic potential and adoption concentrated in areas with dense populations. GHP adoption was projected to 251 GW-th by 2050 with high incentives and tax credits, while TEN adoption was projected at 31 GW-th by 2050. Uncertainties in cost structure translate to large variations in adoption, pointing to the importance of demonstration projects and cost-tracking efforts.”

4. 4

   Solar PVT-assisted high-temperature CO2 heat pump with thermal storage: Design for net-zero electricity operation and ethical sustainability.

   PloS one (Ma et al.)Published Jun 2, 2026Checked Oct 15, 2026

   “Results show that at least 32 PVT modules are required to guarantee 24 h stable operation, with the storage temperature and heat pump COP (Coefficient of performance) exhibiting a decrease-increase-decrease trend throughout the day; as the initial storage temperature increases from 25 °C to 50 °C, the average COP rises from 3.59 to 4.37. For a given number of PVT modules, the net daily electrical output increases with storage volume and significantly increases with the initial storage temperature, varying from -6.06 kWh to 2.32 kWh within the investigated range, and reaching its maximum at a storage volume of 5 m³ and an initial temperature of 50 °C. A storage volume of 4.4 m³ and an initial temperature of 42 °C yield a net daily electrical output of approximately zero, i.e., the electricity generated by the PVT field fully compensates the compressor consumption. Under this self-sufficient condition, the maximum instantaneous electrical efficiency gain of the PVT modules compared with a standalone PV array is 5.03%, while the maximum hourly PVT electrical output and net electrical output reach 5.91 kWh and 3.43 kWh, respectively.”

5. 5

   Multimodal modeling framework and characteristic analysis of a new air-source heat pump heating system.

   Scientific reports (Jiang et al.)Published Jun 3, 2026Checked Oct 15, 2026

   “To address this issue, this paper develops a novel prediction model called XMS (XGBoost, MLP, and Stacking model). First, heating data from an operational air-source heat pump system coupled with a phase-change energy storage tank are collected. Second, the XMS model is proposed, based on a stacking ensemble strategy. It integrates XGBoost and a multi-layer perceptron (MLP) as base learners and employs a meta-learner to perform secondary modeling of their outputs. Finally, the XMS model is compared with a traditional MLP model. The results indicate that the XMS model demonstrates significantly superior predictive performance compared to the MLP model, achieving a 22.5% reduction in root mean square error (RMSE) and a 10.1% increase in the coefficient of determination (R²). The XMS model better captures the nonlinear and multivariate coupling characteristics of the heating system. This study provides an efficient and reliable modeling method for load forecasting and control optimization in air-source heat pump phase-change energy storage heating systems, offering valuable guidance for intelligent heating control technology.”