Upgrading and retrofitting air conditioning systems with energy-efficient upgrades is a smart choice for both homeowners and businesses looking to save money on their energy bills while reducing their environmental impact. These upgrades can include installing programmable thermostats, upgrading to high-efficiency HVAC units, improving insulation, sealing ductwork, and implementing smart technologies.
By making these upgrades, you can significantly decrease your energy consumption and lower your utility costs. Energy-efficient air conditioning systems use less energy to cool your space, which not only saves you money but also reduces greenhouse gas emissions. This is particularly important as we strive to combat climate change and preserve our planet for future generations.
In addition to the financial and environmental benefits, energy-efficient upgrades can also increase the comfort of your home or business. By ensuring that your air conditioning system is running at its optimal efficiency, you can enjoy more consistent temperatures throughout your space and improved indoor air quality.
Overall, investing in energy-efficient upgrades for your air conditioning system is a win-win situation. You'll save money on your energy bills, reduce your carbon footprint, and create a more comfortable living or working environment. So why wait? Start exploring the options for upgrading your air conditioning system today!
Older air conditioning units can often be inefficient and prone to breakdowns, leading to higher energy costs and frustration for homeowners. However, retrofitting these units can offer a number of benefits that make them a worthwhile investment.
One of the main benefits of retrofitting older air conditioning units is increased energy efficiency. By upgrading components such as motors, compressors, and coils, older units can operate more efficiently and effectively, resulting in lower energy bills and reduced carbon emissions. This not only saves money in the long run but also helps to protect the environment by reducing energy consumption.
Retrofitting also extends the lifespan of older air conditioning units, potentially saving homeowners thousands of dollars on replacement costs. By replacing worn-out parts and upgrading components, retrofitted units can continue to provide reliable cooling for years to come. This can be especially beneficial for homeowners who are not yet ready to invest in a completely new system but still want to improve their comfort and efficiency.
In addition to cost savings and improved performance, retrofitting older air conditioning units can also enhance indoor comfort. Upgraded components can improve airflow, reduce noise levels, and provide better temperature control, creating a more comfortable living environment for homeowners. This can lead to increased satisfaction with the cooling system and overall quality of life.
Overall, retrofitting older air conditioning units offers a range of benefits that make it a smart choice for homeowners looking to upgrade their systems. From increased energy efficiency and cost savings to extended lifespan and improved comfort, retrofitting can help older units perform like new again. With these advantages in mind, it's clear that investing in retrofitting is a decision that pays off in both the short and long term.
When considering upgrades and retrofitting for air conditioning systems, one crucial aspect to take into account is the cost analysis. This evaluation helps determine the financial implications of making changes to an existing system in order to improve its efficiency or performance.
Upgrades and retrofitting can involve a variety of changes, such as installing new components, replacing old equipment, or implementing advanced technologies. Each of these modifications comes with its own costs, which need to be carefully assessed before proceeding with any work.
Cost analysis of upgrades and retrofitting involves calculating both the initial investment required for the changes as well as the potential long-term savings that may result from improved energy efficiency or reduced maintenance costs. It is important to weigh these factors against each other to determine whether the benefits of upgrading outweigh the expenses involved.
In addition to direct costs, it is also essential to consider indirect expenses such as downtime during installation, training for personnel on new systems, and any potential disruptions to daily operations. These factors can impact the overall cost-effectiveness of upgrades and retrofitting projects.
Furthermore, it is advisable to consult with professionals in the field who can provide expert advice on cost-effective solutions tailored to specific needs. By conducting a thorough cost analysis before embarking on upgrades and retrofitting projects for air conditioning systems, businesses can make informed decisions that align with their budget constraints while maximizing long-term benefits.
When it comes to upgrading or retrofitting air conditioning systems, there are a few common mistakes that can easily be avoided with proper planning and attention to detail. One of the most common mistakes is failing to properly assess the needs of the space being cooled. It's important to consider factors such as the size of the space, insulation levels, and any existing ventilation systems in place before making any decisions about upgrading or retrofitting.
Another common mistake is neglecting to properly size the new equipment. It's crucial to ensure that the new air conditioning system is correctly sized for the space it will be cooling in order to maximize efficiency and avoid unnecessary stress on the equipment. Oversized units can lead to short cycling and reduced energy efficiency, while undersized units may struggle to keep up with demand.
Failing to properly maintain and service the new equipment is also a common mistake that can result in issues down the line. Regular maintenance is essential for keeping air conditioning systems running smoothly and efficiently. This includes tasks such as changing filters, cleaning coils, and checking refrigerant levels.
Lastly, overlooking energy efficiency upgrades when retrofitting air conditioning systems can be a costly mistake in the long run. Investing in energy-efficient equipment and technologies can help reduce operating costs and lessen environmental impact. This could include upgrades such as variable-speed drives, programmable thermostats, or high-efficiency filters.
By avoiding these common mistakes and taking a thoughtful approach to upgrading or retrofitting air conditioning systems, you can ensure that your project runs smoothly and effectively. With proper planning and attention to detail, you'll be able to enjoy improved comfort and efficiency for years to come.
Installation Orlando
Cooling is removal of heat, usually resulting in a lower temperature and/or phase change. Temperature lowering achieved by any other means may also be called cooling.[1][2] The transfer of thermal energy may occur via thermal radiation, heat conduction or convection. Examples can be as simple as reducing temperature of a coffee.
Ventilative cooling is the use of natural or mechanical ventilation to cool indoor spaces.[1] The use of outside air reduces the cooling load and the energy consumption of these systems, while maintaining high quality indoor conditions; passive ventilative cooling may eliminate energy consumption. Ventilative cooling strategies are applied in a wide range of buildings and may even be critical to realize renovated or new high efficient buildings and zero-energy buildings (ZEBs).[2] Ventilation is present in buildings mainly for air quality reasons. It can be used additionally to remove both excess heat gains, as well as increase the velocity of the air and thereby widen the thermal comfort range.[3] Ventilative cooling is assessed by long-term evaluation indices.[4] Ventilative cooling is dependent on the availability of appropriate external conditions and on the thermal physical characteristics of the building.
In the last years, overheating in buildings has been a challenge not only during the design stage but also during the operation. The reasons are:[5][6]
In many post-occupancy comfort studies overheating is a frequently reported problem not only during the summer months but also during the transitions periods, also in temperate climates.
The effectiveness of ventilative cooling has been investigated by many researchers and has been documented in many post occupancy assessments reports.[7][8][9] The system cooling effectiveness (natural or mechanical ventilation) depends on the air flow rate that can be established, the thermal capacity of the construction and the heat transfer of the elements. During cold periods the cooling power of outdoor air is large. The risk of draughts is also important. During summer and transition months outdoor air cooling power might not be enough to compensate overheating indoors during daytime and application of ventilative cooling will be limited only during the night period. The night ventilation may remove effectively accumulated heat gains (internal and solar) during daytime in the building constructions.[10] For the assessment of the cooling potential of the location simplified methods have been developed.[11][12][13][14] These methods use mainly building characteristics information, comfort range indices and local climate data. In most of the simplified methods the thermal inertia is ignored.
The critical limitations for ventilative cooling are:
Ventilative cooling requirements in regulations are complex. Energy performance calculations in many countries worldwide do not explicitly consider ventilative cooling. The available tools used for energy performance calculations are not suited to model the impact and effectiveness of ventilative cooling, especially through annual and monthly calculations.[16]
A large number of buildings using ventilative cooling strategies have already been built around the world.[17][18][19] Ventilative cooling can be found not only in traditional, pre-air-condition architecture, but also in temporary European and international low energy buildings. For these buildings passive strategies are priority. When passive strategies are not enough to achieve comfort, active strategies are applied. In most cases for the summer period and the transition months, automatically controlled natural ventilation is used. During the heating season, mechanical ventilation with heat recovery is used for indoor air quality reasons. Most of the buildings present high thermal mass. User behavior is crucial element for successful performance of the method.
Building components of ventilative cooling are applied on all three levels of climate-sensitive building design, i.e. site design, architectural design and technical interventions . A grouping of these components follows:[1][20]
Control strategies in ventilative cooling solutions have to control the magnitude and the direction, of air flows in space and time.[1] Effective control strategies ensure high indoor comfort levels and minimum energy consumption. Strategies in a lot of cases include temperature and CO2 monitoring.[21] In many buildings in which occupants had learned how to operate the systems, energy use reduction was achieved. Main control parameters are operative (air and radiant) temperature (both peak, actual or average), occupancy, carbon dioxide concentration and humidity levels.[21] Automation is more effective than personal control.[1] Manual control or manual override of automatic control are very important as it affects user acceptance and appreciation of the indoor climate positively (also cost).[22] The third option is that operation of facades is left to personal control of the inhabitants, but the building automation system gives active feedback and specific advises.
Building design is characterized by different detailed design levels. In order to support the decision-making process towards ventilative cooling solutions, airflow models with different resolution are used. Depending on the detail resolution required, airflow models can be grouped into two categories:[1]
Existing literature includes reviews of available methods for airflow modelling.[9][23][24][25][26][27][28]
Annex 62 'ventilative cooling' was a research project of the Energy in Buildings and Communities Programme (EBC) of the International Energy Agency (IEA), with a four-year working phase (2014–2018).[29] The main goal was to make ventilative cooling an attractive and energy efficient cooling solution to avoid overheating of both new and renovated buildings. The results from the Annex facilitate better possibilities for prediction and estimation of heat removal and overheating risk – for both design purposes and for energy performance calculation. The documented performance of ventilative cooling systems through analysis of case studies aimed to promote the use of this technology in future high performance and conventional buildings.[30] To fulfill the main goal the Annex had the following targets for the research and development work:
The Annex 62 research work was divided in three subtasks.
A heat pump is a device that uses electricity to transfer heat from a colder place to a warmer place. Specifically, the heat pump transfers thermal energy using a heat pump and refrigeration cycle, cooling the cool space and warming the warm space.[1] In winter a heat pump can move heat from the cool outdoors to warm a house; the pump may also be designed to move heat from the house to the warmer outdoors in summer. As they transfer heat rather than generating heat, they are more energy-efficient than heating by gas boiler.[2]
A gaseous refrigerant is compressed so its pressure and temperature rise. When operating 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 indoor 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. It is now colder than the temperature of the outdoor space being used as a heat source. It can again take up energy from the heat source, be compressed and repeat the cycle.
Air source heat pumps are the most common models, while other types include ground source heat pumps, water source heat pumps and exhaust air heat pumps.[3] Large-scale heat pumps are also used in district heating systems.[4]
The efficiency of a heat pump is expressed as a coefficient of performance (COP), or seasonal coefficient of performance (SCOP). The higher the number, the more efficient a heat pump is. For example, an air-to-water heat pump that produces 6kW at a SCOP of 4.62 will give over 4kW of energy into a heating system for every kilowatt of energy that the heat pump uses itself to operate. When used for space heating, heat pumps are typically more energy-efficient than electric resistance and other heaters.
Because of their high efficiency and the increasing share of fossil-free sources in electrical grids, heat pumps are playing a role in climate change mitigation.[5][6] Consuming 1 kWh of electricity, they can transfer 1[7] to 4.5 kWh of thermal energy into a building. The carbon footprint of heat pumps depends on how electricity is generated, but they usually reduce emissions.[8] Heat pumps could satisfy over 80% of global space and water heating needs with a lower carbon footprint than gas-fired condensing boilers: however, in 2021 they only met 10%.[4]
Heat flows spontaneously from a region of higher temperature to a region of lower temperature. Heat does not flow spontaneously from lower temperature to higher, but it can be made to flow in this direction if work is performed. The work required to transfer a given amount of heat is usually much less than the amount of heat; this is the motivation for using heat pumps in applications such as the heating of water and the interior of buildings.[9]
The amount of work required to drive an amount of heat Q from a lower-temperature reservoir such as ambient air to a higher-temperature reservoir such as the interior of a building is: W = Q C O P \displaystyle W=\frac Q\mathrm COP where
The coefficient of performance of a heat pump is greater than one so the work required is less than the heat transferred, making a heat pump a more efficient form of heating than electrical resistance heating. As the temperature of the higher-temperature reservoir increases in response to the heat flowing into it, the coefficient of performance decreases, causing an increasing amount of work to be required for each unit of heat being transferred.[9]
The coefficient of performance, and the work required by a heat pump can be calculated easily by considering an ideal heat pump operating on the reversed Carnot cycle:
This is the theoretical amount of heat pumped but in practice it will be less for various reasons, for example if the outside unit has been installed where there is not enough airflow. More data sharing with owners and academics—perhaps from heat meters—could improve efficiency in the long run.[11]
Milestones:
An air source heat pump (ASHP) is a heat pump that can absorb heat from air outside a building and release it inside; it uses the same vapor-compression refrigeration process and much the same equipment as an air conditioner, but in the opposite direction. ASHPs are the most common type of heat pump and, usually being smaller, tend to be used to heat individual houses or flats rather than blocks, districts or industrial processes.[20]
Air-to-air heat pumps provide hot or cold air directly to rooms, but do not usually provide hot water. Air-to-water heat pumps use radiators or underfloor heating to heat a whole house and are often also used to provide domestic hot water.
An ASHP can typically gain 4 kWh thermal energy from 1 kWh electric energy. They are optimized for flow temperatures between 30 and 40 °C (86 and 104 °F), suitable for buildings with heat emitters sized for low flow temperatures. With losses in efficiency, an ASHP can even provide full central heating with a flow temperature up to 80 °C (176 °F).[21]
As of 2023[update] about 10% of building heating worldwide is from ASHPs. They are the main way to phase out gas boilers (also known as "furnaces") from houses, to avoid their greenhouse gas emissions.[22]
Air-source heat pumps are used to move heat between two heat exchangers, one outside the building which is fitted with fins through which air is forced using a fan and the other which either directly heats the air inside the building or heats water which is then circulated around the building through radiators or underfloor heating which releases the heat to the building. These devices can also operate in a cooling mode where they extract heat via the internal heat exchanger and eject it into the ambient air using the external heat exchanger. Some can be used to heat water for washing which is stored in a domestic hot water tank.[23]
Air-source heat pumps are relatively easy and inexpensive to install, so are the most widely used type. In mild weather, coefficient of performance (COP) may be between 2 and 5, while at temperatures below around −8 °C (18 °F) an air-source heat pump may still achieve a COP of 1 to 4.[24]
A ground source heat pump (also geothermal heat pump) is a heating/cooling system for buildings that use a type of heat pump to transfer heat to or from the ground, taking advantage of the relative constancy of temperatures of the earth through the seasons. Ground-source heat pumps (GSHPs)—or geothermal heat pumps (GHP), as they are commonly termed in North America—are among the most energy-efficient technologies for providing HVAC and water heating, using less energy than can be achieved by use of resistive electric heaters.
Exhaust air heat pumps extract heat from the exhaust air of a building and require mechanical ventilation. Two classes exist:
A solar-assisted heat pump (SAHP) is a machine that combines a heat pump and thermal solar panels and/or PV solar panels in a single integrated system.[27] Typically these two technologies are used separately (or only placing them in parallel) to produce hot water.[28] In this system the solar thermal panel performs the function of the low temperature heat source and the heat produced is used to feed the heat pump's evaporator.[29] The goal of this system is to get high coefficient of performance (COP) and then produce energy in a more efficient and less expensive way.
Likewise PV can simply be used to power the heat pump electrically to enable electrification of heating buildings[30] and greenhouses.[31] These systems enable electrification[32] of heating/cooling and are normally driven by economics[33] and decarbonization goals.[34] Such systems have been shown to be economic in the Middle East,[35] North America,[36] Asia[37] and Europe.[38]
A water-source heat pump works in a similar manner to a ground-source heat pump, except that it takes heat from a body of water rather than the ground. The body of water does, however, need to be large enough to be able to withstand the cooling effect of the unit without freezing or creating an adverse effect for wildlife.[39] The largest water-source heat pump was installed in the Danish town of Esbjerg in 2023.[40][41]
A thermoacoustic heat pump operates as a thermoacoustic heat engine without refrigerant but instead uses a standing wave in a sealed chamber driven by a loudspeaker to achieve a temperature difference across the chamber.[42]
Electrocaloric heat pumps are solid state.[43]
The International Energy Agency estimated that, as of 2021, heat pumps installed in buildings have a combined capacity of more than 1000 GW.[4] They are used for heating, ventilation, and air conditioning (HVAC) and may also provide domestic hot water and tumble clothes drying.[44] The purchase costs are supported in various countries by consumer rebates.[45]
In HVAC applications, a heat pump is typically a vapor-compression refrigeration device that includes a reversing valve and optimized heat exchangers so that the direction of heat flow (thermal energy movement) may be reversed. The reversing valve switches the direction of refrigerant through the cycle and therefore the heat pump may deliver either heating or cooling to a building.
Because the two heat exchangers, the condenser and evaporator, must swap functions, they are optimized to perform adequately in both modes. Therefore, the Seasonal Energy Efficiency Rating (SEER in the US) or European seasonal energy efficiency ratio of a reversible heat pump is typically slightly less than those of two separately optimized machines. For equipment to receive the US Energy Star rating, it must have a rating of at least 14 SEER. Pumps with ratings of 18 SEER or above are considered highly efficient. The highest efficiency heat pumps manufactured are up to 24 SEER.[46]
Heating seasonal performance factor (in the US) or Seasonal Performance Factor (in Europe) are ratings of heating performance. The SPF is Total heat output per annum / Total electricity consumed per annum in other words the average heating COP over the year.[47]
Window mounted heat pumps run on standard 120v AC outlets and provide heating, cooling, and humidity control. They are more efficient with lower noise levels, condensation management, and a smaller footprint than window mounted air conditioners that just do cooling.[48]
In water heating applications, heat pumps may be used to heat or preheat water for swimming pools, homes or industry. Usually heat is extracted from outdoor air and transferred to an indoor water tank.[49][50]
Large (megawatt-scale) heat pumps are used for district heating.[51] However as of 2022[update] about 90% of district heat is from fossil fuels.[52] In Europe, heat pumps account for a mere 1% of heat supply in district heating networks but several countries have targets to decarbonise their networks between 2030 and 2040.[4] Possible sources of heat for such applications are sewage water, ambient water (e.g. sea, lake and river water), industrial waste heat, geothermal energy, flue gas, waste heat from district cooling and heat from solar seasonal thermal energy storage.[53] Large-scale heat pumps for district heating combined with thermal energy storage offer high flexibility for the integration of variable renewable energy. Therefore, they are regarded as a key technology for limiting climate change by phasing out fossil fuels.[53][54] They are also a crucial element of systems which can both heat and cool districts.[55]
There is great potential to reduce the energy consumption and related greenhouse gas emissions in industry by application of industrial heat pumps, for example for process heat.[56][57] Short payback periods of less than 2 years are possible, while achieving a high reduction of CO2 emissions (in some cases more than 50%).[58][59] Industrial heat pumps can heat up to 200 °C, and can meet the heating demands of many light industries.[60][61] In Europe alone, 15 GW of heat pumps could be installed in 3,000 facilities in the paper, food and chemicals industries.[4]
The performance of a heat pump is determined by the ability of the pump to extract heat from a low temperature environment (the source) and deliver it to a higher temperature environment (the sink).[62] Performance varies, depending on installation details, temperature differences, site elevation, location on site, pipe runs, flow rates, and maintenance.
In general, heat pumps work most efficiently (that is, the heat output produced for a given energy input) when the difference between the heat source and the heat sink is small. When using a heat pump for space or water heating, therefore, the heat pump will be most efficient in mild conditions, and decline in efficiency on very cold days. Performance metrics supplied to consumers attempt to take this variation into account.
Common performance metrics are the SEER (in cooling mode) and seasonal coefficient of performance (SCOP) (commonly used just for heating), although SCOP can be used for both modes of operation.[62] Larger values of either metric indicate better performance.[62] When comparing the performance of heat pumps, the term performance is preferred to efficiency, with coefficient of performance (COP) being used to describe the ratio of useful heat movement per work input.[62] An electrical resistance heater has a COP of 1.0, which is considerably lower than a well-designed heat pump which will typically have a COP of 3 to 5 with an external temperature of 10 °C and an internal temperature of 20 °C. Because the ground is a constant temperature source, a ground-source heat pump is not subjected to large temperature fluctuations, and therefore is the most energy-efficient type of heat pump.[62]
The "seasonal coefficient of performance" (SCOP) is a measure of the aggregate energy efficiency measure over a period of one year which is dependent on regional climate.[62] One framework for this calculation is given by the Commission Regulation (EU) No. 813/2013.[63]
A heat pump's operating performance in cooling mode is characterized in the US by either its energy efficiency ratio (EER) or seasonal energy efficiency ratio (SEER), both of which have units of BTU/(h·W) (note that 1 BTU/(h·W) = 0.293 W/W) and larger values indicate better performance.
The carbon footprint of heat pumps depends on their individual efficiency and how electricity is produced. An increasing share of low-carbon energy sources such as wind and solar will lower the impact on the climate.
In most settings, heat pumps will reduce CO2 emissions compared to heating systems powered by fossil fuels.[70] In regions accounting for 70% of world energy consumption, the emissions savings of heat pumps compared with a high-efficiency gas boiler are on average above 45% and reach 80% in countries with cleaner electricity mixes.[4] These values can be improved by 10 percentage points, respectively, with alternative refrigerants. In the United States, 70% of houses could reduce emissions by installing a heat pump.[71][4] The rising share of renewable electricity generation in many countries is set to increase the emissions savings from heat pumps over time.[4]
Heating systems powered by green hydrogen are also low-carbon and may become competitors, but are much less efficient due to the energy loss associated with hydrogen conversion, transport and use. In addition, not enough green hydrogen is expected to be available before the 2030s or 2040s.[72][73]
Vapor-compression uses a circulating refrigerant as the medium which absorbs heat from one space, compresses it thereby increasing its temperature before releasing it in another space. The system normally has eight main components: a compressor, a reservoir, a reversing valve which selects between heating and cooling mode, two thermal expansion valves (one used when in heating mode and the other when used in cooling mode) and two heat exchangers, one associated with the external heat source/sink and the other with the interior. In heating mode the external heat exchanger is the evaporator and the internal one being the condenser; in cooling mode the roles are reversed.
Circulating refrigerant enters the compressor in the thermodynamic state known as a saturated vapor[74] and is compressed to a higher pressure, resulting in a higher temperature as well. The hot, compressed vapor is then in the thermodynamic state known as a superheated vapor and it is at a temperature and pressure at which it can be condensed with either cooling water or cooling air flowing across the coil or tubes. In heating mode this heat is used to heat the building using the internal heat exchanger, and in cooling mode this heat is rejected via the external heat exchanger.
The condensed, liquid refrigerant, in the thermodynamic state known as a saturated liquid, is next routed through an expansion valve where it undergoes an abrupt reduction in pressure. That pressure reduction results in the adiabatic flash evaporation of a part of the liquid refrigerant. The auto-refrigeration effect of the adiabatic flash evaporation lowers the temperature of the liquid and-vapor refrigerant mixture to where it is colder than the temperature of the enclosed space to be refrigerated.
The cold mixture is then routed through the coil or tubes in the evaporator. A fan circulates the warm air in the enclosed space across the coil or tubes carrying the cold refrigerant liquid and vapor mixture. That warm air evaporates the liquid part of the cold refrigerant mixture. At the same time, the circulating air is cooled and thus lowers the temperature of the enclosed space to the desired temperature. The evaporator is where the circulating refrigerant absorbs and removes heat which is subsequently rejected in the condenser and transferred elsewhere by the water or air used in the condenser.
To complete the refrigeration cycle, the refrigerant vapor from the evaporator is again a saturated vapor and is routed back into the compressor.
Over time, the evaporator may collect ice or water from ambient humidity. The ice is melted through defrosting cycle. An internal heat exchanger is either used to heat/cool the interior air directly or to heat water that is then circulated through radiators or underfloor heating circuit to either heat or cool the buildings.
Heat input can be improved if the refrigerant enters the evaporator with a lower vapor content. This can be achieved by cooling the liquid refrigerant after condensation. The gaseous refrigerant condenses on the heat exchange surface of the condenser. To achieve a heat flow from the gaseous flow center to the wall of the condenser, the temperature of the liquid refrigerant must be lower than the condensation temperature.
Additional subcooling can be achieved by heat exchange between relatively warm liquid refrigerant leaving the condenser and the cooler refrigerant vapor emerging from the evaporator. The enthalpy difference required for the subcooling leads to the superheating of the vapor drawn into the compressor. When the increase in cooling achieved by subcooling is greater that the compressor drive input required to overcome the additional pressure losses, such a heat exchange improves the coefficient of performance.[75]
One disadvantage of the subcooling of liquids is that the difference between the condensing temperature and the heat-sink temperature must be larger. This leads to a moderately high pressure difference between condensing and evaporating pressure, whereby the compressor energy increases.[citation needed]
Pure refrigerants can be divided into organic substances (hydrocarbons (HCs), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), and HCFOs), and inorganic substances (ammonia (NH 3), carbon dioxide (CO 2), and water (H 2O)[76]).[77] Their boiling points are usually below −25 °C.[78]
In the past 200 years, the standards and requirements for new refrigerants have changed. Nowadays low global warming potential (GWP) is required, in addition to all the previous requirements for safety, practicality, material compatibility, appropriate atmospheric life,[clarification needed] and compatibility with high-efficiency products. By 2022, devices using refrigerants with a very low GWP still have a small market share but are expected to play an increasing role due to enforced regulations,[79] as most countries have now ratified the Kigali Amendment to ban HFCs.[80] Isobutane (R600A) and propane (R290) are far less harmful to the environment than conventional hydrofluorocarbons (HFC) and are already being used in air-source heat pumps.[81] Propane may be the most suitable for high temperature heat pumps.[82] Ammonia (R717) and carbon dioxide (R-744) also have a low GWP. As of 2023[update] smaller CO 2 heat pumps are not widely available and research and development of them continues.[83] A 2024 report said that refrigerants with GWP are vulnerable to further international restrictions.[84]
Until the 1990s, heat pumps, along with fridges and other related products used chlorofluorocarbons (CFCs) as refrigerants, which caused major damage to the ozone layer when released into the atmosphere. Use of these chemicals was banned or severely restricted by the Montreal Protocol of August 1987.[85]
Replacements, including R-134a and R-410A, are hydrofluorocarbons (HFC) with similar thermodynamic properties with insignificant ozone depletion potential (ODP) but had problematic GWP.[86] HFCs are powerful greenhouse gases which contribute to climate change.[87][88] Dimethyl ether (DME) also gained in popularity as a refrigerant in combination with R404a.[89] More recent refrigerants include difluoromethane (R32) with a lower GWP, but still over 600.
Devices with R-290 refrigerant (propane) are expected to play a key role in the future.[82][93] The 100-year GWP of propane, at 0.02, is extremely low and is approximately 7000 times less than R-32. However, the flammability of propane requires additional safety measures: the maximum safe charges have been set significantly lower than for lower flammability refrigerants (only allowing approximately 13.5 times less refrigerant in the system than R-32).[94][95][96] This means that R-290 is not suitable for all situations or locations. Nonetheless, by 2022, an increasing number of devices with R-290 were offered for domestic use, especially in Europe.[citation needed]
At the same time,[when?] HFC refrigerants still dominate the market. Recent government mandates have seen the phase-out of R-22 refrigerant. Replacements such as R-32 and R-410A are being promoted as environmentally friendly but still have a high GWP.[97] A heat pump typically uses 3 kg of refrigerant. With R-32 this amount still has a 20-year impact equivalent to 7 tons of CO2, which corresponds to two years of natural gas heating in an average household. Refrigerants with a high ODP have already been phased out.[citation needed]
Financial incentives aim to protect consumers from high fossil gas costs and to reduce greenhouse gas emissions,[98] and are currently available in more than 30 countries around the world, covering more than 70% of global heating demand in 2021.[4]
Food processors, brewers, petfood producers and other industrial energy users are exploring whether it is feasible to use renewable energy to produce industrial-grade heat. Process heating accounts for the largest share of onsite energy use in Australian manufacturing, with lower-temperature operations like food production particularly well-suited to transition to renewables.
To help producers understand how they could benefit from making the switch, the Australian Renewable Energy Agency (ARENA) provided funding to the Australian Alliance for Energy Productivity (A2EP) to undertake pre-feasibility studies at a range of sites around Australia, with the most promising locations advancing to full feasibility studies.[99]
In an effort to incentivize energy efficiency and reduce environmental impact, the Australian states of Victoria, New South Wales, and Queensland have implemented rebate programs targeting the upgrade of existing hot water systems. These programs specifically encourage the transition from traditional gas or electric systems to heat pump based systems.[100][101][102][103][104]
In 2022, the Canada Greener Homes Grant[105] provides up to $5000 for upgrades (including certain heat pumps), and $600 for energy efficiency evaluations.
Purchase subsidies in rural areas in the 2010s reduced burning coal for heating, which had been causing ill health.[106]
In the 2024 report by the International Energy Agency (IEA) titled "The Future of Heat Pumps in China," it is highlighted that China, as the world's largest market for heat pumps in buildings, plays a critical role in the global industry. The country accounts for over one-quarter of global sales, with a 12% increase in 2023 alone, despite a global sales dip of 3% the same year.[107]
Heat pumps are now used in approximately 8% of all heating equipment sales for buildings in China as of 2022, and they are increasingly becoming the norm in central and southern regions for both heating and cooling. Despite their higher upfront costs and relatively low awareness, heat pumps are favored for their energy efficiency, consuming three to five times less energy than electric heaters or fossil fuel-based solutions. Currently, decentralized heat pumps installed in Chinese buildings represent a quarter of the global installed capacity, with a total capacity exceeding 250 GW, which covers around 4% of the heating needs in buildings.[107]
Under the Announced Pledges Scenario (APS), which aligns with China's carbon neutrality goals, the capacity is expected to reach 1,400 GW by 2050, meeting 25% of heating needs. This scenario would require an installation of about 100 GW of heat pumps annually until 2050. Furthermore, the heat pump sector in China employs over 300,000 people, with employment numbers expected to double by 2050, underscoring the importance of vocational training for industry growth. This robust development in the heat pump market is set to play a significant role in reducing direct emissions in buildings by 30% and cutting PM2.5 emissions from residential heating by nearly 80% by 2030.[107][108]
To speed up the deployment rate of heat pumps, the European Commission launched the Heat Pump Accelerator Platform in November 2024.[109] It will encourage industry experts, policymakers, and stakeholders to collaborate, share best practices and ideas, and jointly discuss measures that promote sustainable heating solutions.[110]
Until 2027 fixed heat pumps have no Value Added Tax (VAT).[111] As of 2022[update] the installation cost of a heat pump is more than a gas boiler, but with the "Boiler Upgrade Scheme"[112] government grant and assuming electricity/gas costs remain similar their lifetime costs would be similar on average.[113] However lifetime cost relative to a gas boiler varies considerably depending on several factors, such as the quality of the heat pump installation and the tariff used.[114] In 2024 England was criticised for still allowing new homes to be built with gas boilers, unlike some other counties where this is banned.[115]
The High-efficiency Electric Home Rebate Program was created in 2022 to award grants to State energy offices and Indian Tribes in order to establish state-wide high-efficiency electric-home rebates. Effective immediately, American households are eligible for a tax credit to cover the costs of buying and installing a heat pump, up to $2,000. Starting in 2023, low- and moderate-level income households will be eligible for a heat-pump rebate of up to $8,000.[116]
In 2022, more heat pumps were sold in the United States than natural gas furnaces.[117]
In November 2023 Biden's administration allocated 169 million dollars from the Inflation Reduction Act to speed up production of heat pumps. It used the Defense Production Act to do so, because according to the administration, energy that is better for the climate is also better for national security.[118]
Photovoltaic-thermal direct expansion solar assisted heat pump (PV/T-DX-SAHP) system enables to benefit the waste heat for evaporation of refrigerant in PV/T collector-evaporator, while providing better cooling for PV cells (Yao et al., 2020).