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Use Heat Pumps

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Heat pumps

Heat pumps use electricity to efficiently move heat from one place to another. This solution focuses on the replacement of fossil fuel-based heating systems with electric heat pumps. Heat pumps are remarkably efficient because they collect heat from the outside air, ground, or water using a refrigerant and use a pump to move the heat into buildings to keep them warm in colder months. Heat pumps typically replace heating systems such as boilers, furnaces, and electric resistance heaters. Many will also replace air conditioners, because the same pump can move heat out of a building in warmer months. 

Last updated September 2, 2025

Solution Basics

heat pump systems

t CO₂-eq (100-yr)/unit/yr
0.95
units
Current 1.3×10⁸ 06×10⁸9.6×10⁸
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0.12 0.570.91
US$ per t CO₂-eq
-200
Gradual

CO₂ , CH₄, N₂O, BC

Additional Benefits

177
183,187
    183
    • 184
    • 185
    • 186
    • 187
    • 188

Overview

Heat pumps use a refrigerant cycle to move heat. When the liquid refrigerant enters a low pressure environment, it absorbs heat from the surrounding air (air-source heat pumps), water, or ground (ground-source heat pumps) as it evaporates. When the refrigerant vapor is compressed, it condenses back into a liquid, releasing the stored heat into the building. By passing the refrigerant through this cycle, a heat pump can move heat from outside to inside a building. 

Absorbing heat from the outside gets more difficult as temperatures drop. However, modern cold-climate heat pumps are designed to work effectively at temperatures approaching –30 °C (–22 °F) (Gibb et al., 2023). The freezer in your home uses the same technology, moving heat out of the cold box into the warm room to keep your food frozen. In most systems, the refrigerant cycle in a heat pump can be reversed in warmer months, moving heat out of a building to ensure its occupants are comfortable year-round. 

Heat pumps are very efficient at using electricity for heating. This is because they move heat rather than generating heat (e.g., by combustion). For example, a heat pump may have a seasonal coefficient of performance (SCOP) of 3, meaning it can move an average of three units of heat energy for every unit of electrical energy that it consumes. Conventional combustion and electric resistance heaters cannot produce more than one unit of heat energy for every unit of fuel energy or electrical energy provided. 

Heat pump systems may be all-electric or hybrid, where a secondary fossil fuel-based heating system takes over in colder weather. 

A heat pump’s potential to reduce GHG emissions depends on the heating source it replaces and the emissions intensity of the electricity used to run it. When heat pumps replace fossil fuel-based heating, they displace the GHG emissions – primarily CO₂ – generated when the fuel is burned. When replacing electric resistance heaters, heat pumps reduce the GHG emissions from the electricity to power the system because heat pumps are much more energy efficient. As electrical grids decarbonize, the GHG emissions from operating heat pumps will decrease. 

All-electric heat pumps provide the most climate benefit because they can be powered with clean energy, but hybrid heat pumps also play an important emissions-reduction role. Hybrids consist of a smaller electric heat pump system that switches to fuel-based heating systems in colder weather. They may be attractive due to lower up-front costs and because they have lower peak power demand on cold days, but hybrids also have a smaller emissions impact. Our cost and emissions analyses assumed all-electric air-source heat pumps, while the data used in the adoption analysis included all types of heat pumps with the expectation that all-electric versions will dominate in the longer term. 

In this analysis, we calculated effectiveness and cost outcomes from specific countries with high heat-pump adoption (European countries, Canada, the United States, Japan, and China) to avoid comparing research studies that use different assumptions. The analysis used global assumptions for heating system efficiency: 90% for fueled systems (International Gas Union, 2019), 100% for electric resistance (U.S. Department of Energy [U.S. DOE], n.d.), and SCOP of 3 for heat pumps (Crownhart, 2023). We also assumed all existing fueled systems use natural gas, which is currently the dominant fossil fuel used for space heating globally (International Energy Agency [IEA], 2023b). The analysis did not include emissions or costs from cooling but did assume the heat pump is replacing both a heating and cooling system. 

The cost and effectiveness analyses focused on residential heating systems due to availability of data and also because large variations in the cost and size of commercial systems make it more challenging to estimate their global impacts. Commercial heating systems are typically larger than residential systems, and their emissions impacts are expected to be proportionally greater per unit. Cost savings may be different due the greater complexity of heating and cooling systems (Tejani & Toshniwal, 2023). Available data on heat pump adoption, on the other hand, typically include both residential and commercial units. Our adoption analysis therefore included both residential and commercial buildings, with greater adoption assumed in the residential sector. 

Impact Calculator

Adjust effectiveness and adoption using range sliders to see resulting climate impact potential.

Effectiveness

0.95
t CO2-eq/heat pump systems/yr

Adoption

1.3×10⁸
heat pump systems
Low
6×10⁸
High
9.6×10⁸
1.3×10⁸
current
Achievable Range

Climate Impact

0.12
Gt CO₂-eq/yr (100-yr)
05
which is the equivalent of
0.21%
of global emissions

The Details

Current State

Our analysis showed that each all-electric residential heat pump for space heating reduces emissions by an average of 0.95 t CO₂‑eq /heat pump system/yr (20-yr and 100-yr basis, Table 1). 

Heat pumps reduce emissions by reducing the amount of fossil fuels burned for space heating or by reducing the use of less efficient electric resistance heating. Operating a heat pump generates no on-site emissions except refrigerant leaks, which are addressed by the Improve Refrigerant Management solution. Our analysis included the emissions from the electricity used to power heat pumps. Thus, the emissions reduction from heat pump adoption is expected to improve as electricity generation incorporates more renewable energy (Knobloch et al., 2020). 

There are significant regional differences in heat pump effectiveness due to the electricity mix, climate, and types of heating systems used today (Knobloch et al., 2020). The global average is weighted based on regional heating requirements and existing heating technologies. 

We did not quantify the reduction in pollutants such as nitrogen oxides, sulfur oxides, and particulate matter, which are released when fossil fuels are burned for space heating. We also refrained from estimating the global warming impacts of refrigerant leaks associated with the use of heat pumps, which is addressed by our Improve Refrigerant Management solution, or natural gas leaks associated with the use of fossil fuels for heating. 

Table 1. Effectiveness at reducing emissions from space heating.

Unit: t CO₂‑eq/heat pump system/yr, 100-yr basis

mean 0.95

A residential air-source heat pump has a mean initial installed cost of US$6,800 and an estimated US$540/yr operational cost for heating. Over a 15-year lifespan, this results in a net cost of US$990/yr. A heat pump generally replaces both a heating and cooling system with a combined mean installed cost of US$5,300. Operating a baseline heating system costs US$830/yr (operational cooling cost was not included in this analysis). Over a 15-year lifespan, the baseline case has a net cost of US$1,180/yr. This results in a net US$190 savings for households that switch to a heat pump. This translates to US$200 savings/t CO₂‑eq reduced (Table 2).

These values include the average annual cost to operate the equipment for heating and the annualized up-front cost of a heat pump relative to both a heating and cooling system that it replaces. There can be significant variability in the up-front cost of equipment based on the type of heat pump installed, the size of the building, and the climate in which it is designed to operate. We assumed the cost to operate the equipment for cooling to be the same with heat pumps and the air conditioners they replace. 

There are significant regional differences in the operational cost of heating systems due to climate, utility rates, and the heating systems in use today. The global average outcomes described here are weighted averages from Europe, Canada, the United States, China, and Japan based on regional heating requirements and existing heating technologies. 

Utility cost estimates are from June 2023 (Global Petrol Prices, 2024) and may vary substantially over time due to factors such as volatile fossil fuel prices, changing carbon prices, and heat pump incentives. Additional installation costs, such as upgrades to electrical systems, ductwork, or radiators, are not included. 

Table 2. Cost per unit climate impact. Negative values reflect cost savings.

Unit: 2023 US$/t CO₂‑eq , 100-yr basis

mean –200

Insufficient data exist to quantify the learning curve for heat pumps. 

The cost of installing a heat pump includes both equipment costs and the labor cost of installation. According to the U.S. Energy Information Administration ([U.S. EIA] 2023), retail equipment costs are 60–80% of the total installed cost of residential air-source heat pumps (central and ductless). 

Equipment costs can decrease with economies of scale and as local markets mature, but may be confounded by technological advances as well as equipment and/or refrigerant regulations that can also increase costs (IEA, 2022). European estimated learning rates for heat pump equipment costs range from 3.3% for ground-source heat pumps (Renaldi et al., 2021) to 18% for air-source heat pumps (Jakob et al., 2020). Ease and cost of installation is a research and development goal for manufacturers (IEA, 2022). 

The installed cost is also affected by rising labor costs and projected labor shortages (IEA, 2022). Renaldi et al. (2021) showed negative learning rates for the total installed costs in the United Kingdom due to increasing installation costs: –2.3% and –0.8% for air-source and ground-source heat pumps, respectively.

Heat pump manufacturer efforts to improve the performance of the technology may impact learning curves as well. In North America, the Residential Heat Pump Technology Challenge has supported the development of heat pumps with improved cold-climate performance (U.S. DOE, 2022). 

Speed of action refers to how quickly a climate solution physically affects the atmosphere after it is deployed. This is different from speed of deployment, which is the pace at which solutions are adopted.

At Project Drawdown, we define the speed of action for each climate solution as emergency brake, gradual, or delayed.

Use Heat Pumps is a GRADUAL climate solution. It has a steady, linear impact on the atmosphere. The cumulative effect over time builds as a straight line.

Adoption

Our analysis suggests that 130 million heat pumps for heating are currently in operation primarily based on data in Europe, Canada, the United States, China, and Japan (Table 3). These include both all-electric heat pumps and hybrid heat pumps. The IEA (2023a) estimated that 12% of global space heating demand was met by heat pumps in 2022. 

This value is based on market reports and national data sources plus IEA (2022) estimates of total GW of installed capacity. To convert installed capacity to the number of heat pumps, we used the median from the range of suggested average capacities (7.5 kW for Europe and North America, 4 kW in Japan and China, 5 kW global average). In Japan, where heat pump units typically heat only one room, we assumed 2.4 units per heat pump (International Renewable Energy Agency [IRENA], 2022).

Table 3. Current heat pump adoption level (2020–2022).

Unit: Heat pump systems in operation

mean 130,000,000

Our estimates put the median adoption trend at 17 million new all-electric and hybrid heat pumps in operation per year (Table 4). This analysis is based on product shipment data (used as a proxy for installed heat pumps), market reports, national statistics, and IEA data for growth in installed capacity. For the IEA data (2010–2023), we assumed a global average of 5 kW of heat capacity per heat pump unit (IEA, 2024).

Shipment and market analysis reports consistently show growing markets for heat pumps in much of the world (Asahi, 2023; European Heat Pump Association, 2024; IEA, 2024). In the United States, shipments of heat pumps have outnumbered gas furnaces since at least 2022 (Air-Conditioning, Heating, and Refrigeration Institute, 2025).

Table 4. Heat pump adoption trend (2010–2023).

Unit: Heat pump systems in operation/yr

25th percentile 12,000,000
mean 15,000,000
median (50th percentile) 17,000,000
75th percentile 18,000,000

Our adoption ceiling is set at 1.200 billion heat pumps for space heating by 2050 (Table 5), most of which are expected to be in residential buildings. This is based on the IEA’s Net Zero Roadmap projection that heat pumps will represent 6,500 GW of heating capacity globally by 2050, covering 55% of space heating demand (IEA, 2023a). Our adoption ceiling assumes all-electric heat pumps cover all space heating demand. 

We assumed that average heat pump sizes (capacities) will increase over time as heat pumps cover a greater portion of a building’s heating load and as more commercial buildings with larger heating loads install heat pumps. Using a global average of 10 kW per heat pump, the IEA projections imply 650 million heat pumps will be in operation by 2050 with the technical adoption ceiling for 1,200 million heat pumps if all heating demand were met by heat pumps.

Table 5. Heat pump adoption ceiling: upper limit for adoption level.

Unit: Heat pump systems in operation by 2050

mean 1,200,000,000

We estimate the achievable range for heat pump adoption to be 600–960 million heat pumps in operation by 2050 (Table 6).

Most existing space heating systems will be replaced at least once between now and 2050 because this equipment typically has lifetimes of 15–30 years (U.S. EIA, 2023). Policies that encourage high efficiency heat pumps alongside insulation upgrades have the potential to provide lifetime savings, greater comfort, and energy efficiency benefits (Wilson et al., 2024). Given the available timelines and potential benefits, near full adoption is technically feasible. 

We have set the Achievable – High heat pump adoption at 80% of the adoption ceiling to account for systems that are difficult to electrify due to very cold climates, policy, economic barriers, and grid constraints. This high achievable value assumes that some systems may be replaced before their end of life to meet climate and/or financial goals. 

We have set the Achievable – Low heat pump adoption at 50% of the adoption ceiling. This is roughly consistent with the current adoption trend continuing out to 2050. 

Our heat pump units adopted include both all-electric and hybrid heat pumps. This analysis assumes that hybrid heat pumps will become less common as fuels are phased out and that all-electric heat pumps will dominate by 2050. 

Table 6. Range of achievable adoption levels.

Unit: Heat pump systems installed

Current Adoption 130,000,000
Achievable – Low 600,000,000
Achievable – High 960,000,000
Adoption Ceiling 1,200,000,000

Impacts

Our estimates show the global impact of existing heat pumps for space heating to be a reduction of 0.12 Gt CO₂‑eq/yr (100- and 20-yr basis) based on current adoption and today’s electricity grid emissions (Table 7). Because electricity grid emissions are decreasing for each kWh of electricity generated (IEA, 2025), the actual impact will be greater than our estimates when future electricity generation emissions are lower.

For the adoption ceiling, assuming heat pumps supply all of the IEA’s projected global heating demand in 2050 (IEA, 2023a), 1.1 Gt CO₂‑eq/yr (100- and 20-yr basis) could be avoided per year with today’s electricity grid emissions.

A high-end achievable target is 80% of the adoption ceiling, accounting for systems that might continue to use fossil fuels for heating due to factors such as cold climates, economic barriers, and grid constraints. This would result in avoiding 0.91 Gt CO₂‑eq/yr (100- and 20-yr basis) with today’s electricity grid emissions. 

A low-end achievable target is 50% of the adoption ceiling, roughly equivalent to heat pump adoption continuing at today’s rate. This would result in avoiding 0.57 Gt CO₂‑eq/yr (100- and 20-yr basis) with today’s electricity grid emissions. 

Table 7. Climate impact at different levels of heat pump systems adoption.

Unit: Gt CO₂‑eq/yr, 100-yr basis

Current Adoption 0.12
Achievable – Low 0.57
Achievable – High 0.91
Adoption Ceiling 1.1

Heat Stress

Heat waves and extreme heat are becoming increasingly significant factors of morbidity and mortality worldwide (Romanello et al., 2024). Some buildings that replace heating systems with heat pumps will gain access to cooling (Congedo et al., 2023; Wilson et al., 2024; Zhang et al., 2017). This can provide protection from heat stress in regions experiencing increasingly hotter summers (where air conditioning was not previously necessary) and for populations that are vulnerable to heat stress, such as the elderly (Malmquist et al., 2022). Some jurisdictions incentivize heat pumps for this reason. For example, the United Kingdom plans to install 600,000 heat pumps by 2028 (Zahiri & Gupta, 2023), and local climate adaptation plans in Canada recommend the installation of heat pumps to provide space cooling that can reduce morbidity and mortality during heat waves (Canadian Climate Institute, 2023; City of Vancouver, n.d.). Because exposure to extreme heat is disproportionately higher for minority communities – particularly in urban environments – access to cooling has important implications for environmental justice (Benz & Burney, 2021). 

Income and Work

Installing heat pumps can lead to greater household savings on electricity. Research has shown that across the United States, heat pumps can reduce electricity bills for 49 million homes with an average savings of US$350–600 per year, depending on the efficiency of the heat pump (Wilson et al., 2024). Wilson et al. (2024) found that higher efficiency heat pumps could be cost-effective for about 65 million households in the United States. Heat pumps also create jobs (Sovacool et al., 2023). In its post-COVID-19 recovery plan, the IEA (2020) estimated that every US$1 million investment in heat pumps could generate 9.1 new jobs and reduce 0.8 jobs in the fossil fuel industry. About half of the new jobs will be in manufacturing, with the remaining distributed between installation and maintenance.

Health

Burning fossil fuels for heating directly emits health-harming particulates and can generate carbon monoxide. Replacing fossil gas heating with heat pumps can reduce air pollution (Carella & D’Orazio, 2021) and contribute to improving health outcomes (Zhou et al., 2022). A study in China showed that as the power grid moves to incorporate renewable energy, the air quality and health benefits of heat pumps will increasingly outweigh the benefits of gas heaters (Zhou et al., 2022). The risk of carbon monoxide poisoning also decreases in buildings that switch from fuel-burning space heating to heat pumps. In buildings that burn fuels for applications such as space heating, carbon monoxide can pose serious health risks, including poisoning and death (Mattiuzzi & Lippi, 2020). 

Other

Heat pumps can increase demand for electricity and can therefore increase demand for fossil fuel-based power generation. In areas where power generation relies heavily on fossil fuels, heat pumps may generate more emissions than gas heating systems. As the electricity sector adopts more renewables and phases out fossil fuel-based generation, the emissions impact of heat pumps will decrease. Once a building has been designed or retrofitted to accommodate a heat pump it is likely that new heat pumps will be installed at the end of equipment life, perpetuating the benefit.

Efforts are underway to retrofit buildings by improving insulation, air-sealing, and upgrading windows. When done alongside heat pump adoption, retrofits can reduce the size of heat pump needed and increase total energy, emissions, and cost savings. 

As heat pump adoption grows, so too will the manufacture of refrigerants, some of which have high global warming potentials when they escape to the atmosphere. See Deploy Alternative Refrigerants and Improve Refrigerant Management solutions for more on accelerating change in this sector.

Heat pumps contain refrigerants that often have high global warming potentials. Refrigerant leaks can occur during installation, operation, and end of life (McDiarmid & Parker, 2024). As more heat pumps are adopted, there is a risk of increased emissions from refrigerant leaks during operation as well as refrigerant release at the end of equipment life. Alternate refrigerants with lower global warming potentials are being phased in due to an international agreement to reduce hydrofluorocarbons, including many refrigerants (Kigali Amendment). 

Higher rates of heat pump installation will require upscaling heat pump manufacturing and training, plus certification of skilled labor to install them. Skilled labor shortages are already creating bottlenecks for heat pump adoption in some countries, some of which can be met by reskilling other heating technicians (IEA, 2022).

Enhanced grid infrastructure will be required to support widespread building electrification and the greater demand for electricity, especially on cold days when heat pumps are less efficient at moving heat (Cooper et al., 2016). Demand-side management, thermal storage, home batteries, bidirectional chargers, and greater adoption of ground-source heat pumps can all help to reduce this increased demand (Cooper et al., 2016; McDiarmid, 2023).

In general, heat pumps have higher up-front costs than do fueled alternatives but will save a building owner money over the lifetime of the system. This can create economic barriers to accessing the benefits of heat pumps, with low-income homeowners and renters who pay for their utilities being particularly vulnerable to being left behind in the transition (Sandoval et al., 2024). Equity advocates are also concerned that the cost of maintaining gas and other fossil fuel infrastructure may increasingly fall on lower-income building owners who struggle to afford the upfront cost of electrifying with heat pumps (Davis & Hausman, 2022). 

Reinforcing

Advancements in heat pump technology will support the development and adoption of heat pump technology for industrial applications. 

Increased adoption of heat pumps will increase the market for alternative refrigerants and refrigerant management.

Competing

Alternative refrigerants require design changes (Kim et al., 2020) that could increase the up-front cost of heat pumps.

Heat pumps could compete with alternatives such as fossil fuel-based district heating and cooling systems that lack heat pumps as well as low-carbon biofuels.

Adoption of heat pumps for space heating is likely to generate seasonal peaks in power demand during cold days that may require building out extra generating capacity that decreases grid efficiency (Bloess et al., 2018). Heat pumps can compete with electric cars for power during peak times (Van Someren et al., 2021).

Consensus of effectiveness in reducing emissions: High

Electric heat pumps are generally viewed as the primary strategy for reducing GHG emissions from buildings. The Intergovernmental Panel on Climate Change ([IPCC] 2023) noted that heat pumps drive electrification in buildings and help decrease emissions. The European Commission (2022) claimed that heat pumps are an essential way of decreasing reliance on gas in heating while increasing the use of renewable energy in the heating sector. The IEA (2022) reported that heat pumps powered by electricity generated with renewable energy “are the central technology in the global transition to secure and sustainable heating.” IRENA (2024) claimed heat pumps in buildings “will play a crucial role in reducing reliance on fossil fuels.” 

In one of the largest scientific reviews on the topic, Gaur et al. (2021) concluded that heat pumps “have the potential to play a substantial role in the transition to low carbon heating,” and noted that emissions impacts of heat pumps are dependent on the type of heat pump technology, their location, and the electricity grid mix. Knobloch et al. (2020) studied 59 world regions and found that electrification of the heating sector via heat pumps will reduce emissions in most world regions where they are adopted.

The results presented in this document summarize findings from 46 reports, reviews and meta-analyses and 13 original studies reflecting current evidence from 30 countries, primarily European countries, Canada, the United States, Japan, and China. We recognize this limited geographic and technology scope creates bias, and hope this work inspires research and data sharing on this topic in underrepresented regions and in the commercial sector.

Take Action

Looking to get involved? Below are some key actions for this solution that can get you started, arranged according to different roles you may play in your professional or personal life.

These actions are meant to be starting points for involvement and are not intended to be prescriptive or necessarily suggest they are the most important or impactful actions to take. We encourage you to explore and get creative!

Lawmakers and Policymakers

  • Introduce zero-carbon ready building codes, clearly designating heat pumps as the default for all new buildings.
  • Incentivize purchases with grants, loans, or tax rebates.
  • Increasing training and support for heat pump installers.
  • Expand the electrical grid and increase renewable energy generation.
  • Streamline permitting processes.
  • Incentivize complementary solutions such as better insulation, thermal storage, and air sealing.
  • Institute a clean heat standard (similar to a renewable energy standard) with a well-defined implementation timeline.
  • Launch performance labels for heating technology.
  • Roll out new energy efficiency programs.

Further information:

Practitioners

  • Commit to zero-carbon construction, clearly designating heat pumps as the default for all new buildings.
  • Increase the available workforce by encouraging trade organizations to promote career and workforce development programs.
  • Design heat pumps that are simpler, faster, and cheaper to install.
  • Educate customers on the benefits and train them on usage.
  • Connect with users and early adopters to understand and adapt to consumer sentiment.
  • Create appealing incentives and financing programs.
  • Partner with builders and developers to improve product adoption and increase market demand for heat pumps.

Further information:

Business Leaders

  • Commit to zero-carbon construction, clearly designating heat pumps as the default for all new buildings.
  • Deploy heat pumps in all owned and operated facilities.
  • Encourage building owners and managers to switch to heat pumps in leased facilities.
  • Promote the benefits of heat pumps and share government incentives with leased facilities and networks.
  • Encourage employees to reduce emissions at home by providing educational resources on the benefits of domestic heat pumps.

Further information:

Nonprofit Leaders

  • Advocate for zero-carbon construction and building codes that clearly designate heat pumps as the default for all new buildings.
  • Deploy heat pumps in owned and operated facilities.
  • Encourage building owners and managers to switch to heat pumps in leased facilities.
  • Educate businesses and communities on the benefits of installing heat pumps and any tax incentives in their region.
  • Advocate to policymakers for improved policies and incentives.
  • Educate community leaders on the need for adoption.

Further information:

Investors

  • Commit to only finance zero-carbon construction with clear requirements for heat pumps as the default for all new development investments.
  • Deploy capital to efforts that improve heat pump performance and reduce material, installation, and maintenance costs.
  • Explore investment opportunities that address supply chain concerns.
  • Consider investments that mitigate non-manufacturing barriers to scaling.
  • Finance heat pump installations via low-interest loans.

Further information:

Philanthropists and International Aid Agencies

  • Directly distribute heat pumps, prioritizing locations where heat pumps maximize emissions reductions, and improve housing affordability.
  • Advocate for zero-carbon construction and building codes that clearly designate heat pumps as the default for all new buildings.
  • Fund R&D efforts and competitions to improve technology, reduce costs, and address supply chain concerns.
  • Support consumer advocacy and education campaigns on heat pumps and how to maximize regulatory incentives.
  • Support training or incentive programs for distributors and installers.

Further information:

Thought Leaders

  • Advocate for zero-carbon construction and building codes that clearly designate heat pumps as the default for all new buildings.
  • Highlight the need to transition away from fossil-fuel-fired heating.
  • Educate the public on the benefits of heat pumps and how they work.
  • Provide case studies that present successes and lessons learned.
  • Increase consumer comfort by including heat pumps in communication content on topics such as home remodeling and construction, technology, health, self-sufficiency, and personal finance.
  • Provide up-to-date user information on available models.

Further information:

Technologists and Researchers

  • Identify safe, cost-effective, and suitable alternative refrigerants.
  • Design systems that require less refrigerant.
  • Work to increase the longevity of heat pumps.
  • Improve heat pumps’ efficiency and capacity at low temperatures as well as their ability to deliver higher temperature heat.
  • Research external social factors critical to adoption.
  • Identify appropriate methods for recycling and disposing of heat pumps and responsibly recovering their refrigerant chemicals at the end of the product life cycle. 

Further information:

Communities, Households, and Individuals

  • Install heat pumps when possible and encourage local heating, ventilation, and air conditioning (HVAC) retailers and installers to sell services and equipment.
  • Increase consumer comfort by sharing your experience and tips for troubleshooting technologies.
  • Advocate for zero-carbon construction and building codes that clearly designate heat pumps as the default for all new buildings.
  • Build support networks for new users and connect to explore innovations.
  • Encourage your property management company, employers, and government officials to accelerate adoption. 

Further information:

“Take Action” Sources

References

Air-Conditioning, Heating, and Refrigeration Institute. (2025). AHRI releases November 2024 U.S. heating and cooling equipment shipment data. Link to source: https://www.ahrinet.org/sites/default/files/Stat%20Release%20Nov%2024/November%202024%20Statistical%20Release.pdf 

Asahi, T. (2023, July 3). The role of heat pumps toward decarbonization [PowerPoint slides]. Japan Refrigeration and Air Conditioning Industry Association. Link to source: https://www.jraia.or.jp/english/relations/file/2023_July_OEWG45_JRAIA_side_event_Presentation_4.pdf 

Benz, S. A., & Burney, J. A. (2021). Widespread race and class disparities in surface urban heat extremes across the United States. Earth’s Future, 9(7), Article e2021EF002016. Link to source: https://doi.org/10.1029/2021EF002016 

Bloess, A., Schill, W.-P., & Zerrahn, A. (2018). Power-to-heat for renewable energy integration: A review of technologies, modeling approaches, and flexibility potentials. Applied Energy, 212, 1611–1626. Link to source: https://doi.org/10.1016/j.apenergy.2017.12.073 

Canadian Climate Institute. (2023). Heat pumps pay off [Report]. Link to source: https://climateinstitute.ca/wp-content/uploads/2023/09/Heat-Pumps-Pay-Off-Unlocking-lower-cost-heating-and-cooling-in-Canada-Canadian-Climate-Institute.pdf 

Carella, A., & D’Orazio, A. (2021). The heat pumps for better urban air quality. Sustainable Cities and Society, 75, Article 103314. Link to source: https://doi.org/10.1016/j.scs.2021.103314 

City of Vancouver. (n.d.). Climate change adaptation strategy [Report]. Retrieved September 2, 2025, from Link to source: https://vancouver.ca/files/cov/vancouver-climate-change-adaptation-strategy-2024-25.pdf 

Congedo, P. M., Baglivo, C., D’Agostino, D., & Mazzeo, D. (2023). The impact of climate change on air source heat pumps. Energy Conversion and Management, 276, Article 116554. Link to source: https://doi.org/10.1016/j.enconman.2022.116554 

Cooper, S. J. G., Hammond, G. P., McManus, M. C., & Pudjianto, D. (2016). Detailed simulation of electrical demands due to nationwide adoption of heat pumps, taking account of renewable generation and mitigation. IET Renewable Power Generation, 10(3), 380–387. Link to source: https://doi.org/10.1049/iet-rpg.2015.0127 

Crownhart, C. (2023, February 14). Everything you need to know about the wild world of heat pumps. MIT Technology Review. Link to source: https://www.technologyreview.com/2023/02/14/1068582/everything-you-need-to-know-about-heat-pumps/ 

Davis, L. W., & Hausman, C. (2022). Who will pay for legacy utility costs? Journal of the Association of Environmental and Resource Economists, 9(6), 1047-1085. Link to source: https://doi.org/10.1086/719793 

European Commission. (2022). REPowerEU: Joint European action for more affordable, secure and sustainable energy. Link to source: https://build-up.ec.europa.eu/en/resources-and-tools/publications/repowereu-joint-european-action-more-affordable-secure-and 

European Heat Pump Association. (2024, February 27). Heat pump sales fall by 5% while EU delays action. Link to source: https://www.ehpa.org/news-and-resources/news/heat-pump-sales-fall-by-5-while-eu-delays-action/ 

Gaur, A. S., Fitiwi, D. Z., & Curtis, J. (2021). Heat pumps and our low-carbon future: A comprehensive review. Energy Research & Social Science, 71, Article 101764. Link to source: https://doi.org/10.1016/j.erss.2020.101764 

Gibb, D., Rosenow, J., Lowes, R., & Hewitt, N. J. (2023). Coming in from the cold: Heat pump efficiency at low temperatures. Joule, 7(9), 1939–1942. Link to source: https://doi.org/10.1016/j.joule.2023.08.005 

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International Gas Union. (2019). Global gas insights 2019 gas & efficiency. Link to source: https://www.igu.org/advocacy/graphics-data/ggi-energy-efficiency 

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Jakob, M., Reiter, U., Krishnan, S., Louwen, A., & Junginger, M. (2020). Chapter 11 - Heating and cooling in the built environment. In M. Junginger & A. Louwen (Eds.), Technological learning in the transition to a low-carbon energy system (pp. 189–219). Academic Press. Link to source: https://doi.org/10.1016/B978-0-12-818762-3.00011-X 

Kim, B., Lee, S. H., Lee, D., & Kim, Y. (2020). Performance comparison of heat pumps using low global warming potential refrigerants with optimized heat exchanger designs. Applied Thermal Engineering, 171, Article 114990. Link to source: https://doi.org/10.1016/j.applthermaleng.2020.114990 

Knobloch, F., Hanssen, S. V., Lam, A., Pollitt, H., Salas, P., Chewpreecha, U., Huijbregts, M. A. J., & Mercure, J.-F. (2020). Net emission reductions from electric cars and heat pumps in 59 world regions over time. Nature Sustainability, 3(6), 437–447. Link to source: https://doi.org/10.1038/s41893-020-0488-7 

Malmquist, A., Hjerpe, M., Glaas, E., Karlsson-Larsson, H., & Lassi, T. (2022). Elderly people’s perceptions of heat stress and adaptation to heat: An interview study. International Journal of Environmental Research and Public Health, 19(7), Article 3775. Link to source: https://doi.org/10.3390/ijerph19073775 

Mattiuzzi, C., & Lippi, G. (2020). Worldwide epidemiology of carbon monoxide poisoning. Human & Experimental Toxicology, 39(4), 387-392. Link to source: https://doi.org/10.1177/0960327119891214 

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Credits

Lead Fellow

  • Heather McDiarmid, Ph.D.

Contributors

  • Stephen Agyeman, Ph.D.

  • Ruthie Burrows, Ph.D.

  • James Gerber, Ph.D.

  • Sarah Gleeson, Ph.D.

  • Yusuf Jameel, Ph.D.

  • Daniel Jasper

  • Jason Lam

  • Cameron Roberts, Ph.D.

  • Alex Sweeney

  • Eric Wilczynski

Internal Reviewers

  • Aiyana Bodi

  • Hannah Henkin

  • Jason Lam

  • Zoltan Nagy, Ph.D.

  • Ted Otte

  • Amanda D. Smith, Ph.D.

Methods and Supporting Data

Methods and Supporting Data

Comments / Questions

  • Greenhouse gas quantity expressed relative to CO₂ with the same warming impact over 100 years, calculated by multiplying emissions by the 100-yr GWP for the emitted gases.

  • Greenhouse gas quantity expressed relative to CO₂ with the same warming impact over 20 years, calculated by multiplying emissions by the 20-yr GWP for the emitted gases.

  • 8th World Congress on Conservation Agriculture

  • Reducing greenhouse gas concentrations in the atmosphere by preventing or reducing emissions.

  • The process of increasing the acidity of water or soil due to increased levels of certain air pollutants.

  • The extent to which emissions reduction or carbon removal is above and beyond what would have occurred without implementing a particular action or solution.

  • An upper limit on solution adoption based on physical or technical constraints, not including economic or policy barriers. This level is unlikely to be reached and will not be exceeded.

  • The quantity and metric to measure implementation for a particular solution that is used as the reference unit for calculations within that solution.

  • The interactions of aerodynamic forces and flexible structures, often including the stucture's control system.

  • Farming practices that work to create socially and ecologically sustainable food production.

  • Addition of trees and shrubs to crop or animal farming systems.

  • Spread out the cost of an asset over its useful lifetime.

  • A crop that live one year or less from planting to harvest; also called annual.

  • black carbon

  • Made from material of biological origin, such as plants, animals, or other organisms.

  • A renewable energy source generated from organic matter from plants and/or algae.

  • An energy source composed primarily of methane and CO₂ that is produced by microorganisms when organic matter decomposes in the absence of oxygen.

  • Carbon stored in biological matter, including soil, plants, fungi, and plant products (e.g., wood, paper, biofuels). This carbon is sequestered from the atmosphere but can be released through decomposition or burning.

  • Living or dead renewable matter from plants or animals, not including organic material transformed into fossil fuels. Peat, in early decay stages, is partially renewable biomass.

  • A type of carbon sequestration that captures carbon from CO₂ via photosynthesis and stores it in soils, sediments, and biomass, distinct from sequestration through chemical or industrial pathways.

  • A climate pollutant, also called soot, produced from incomplete combustion of organic matter, either naturally (wildfires) or from human activities (biomass or fossil fuel burning).

  • High-latitude (>50°N or >50°S) climate regions characterized by short growing seasons and cold temperatures.

  • The components of a building that physically separate the indoors from the outdoor environment.

  • Businesses involved in the sale and/or distribution of solution-related equipment and technology, and businesses that want to support adoption of the solution.

  • A chemical reaction involving heating a solid to a high temperature; to make cement clinker, limestone is calcined into lime in a process that requires high heat and produces CO₂.

  • The ratio of the actual electricity an energy technology generates over a period of time to the maximum it could have produced if it operated at full capacity continuously.

  • A four-wheeled passenger vehicle.

  • Technologies that collect CO₂ before it enters the atmosphere, preventing emissions at their source. Collected CO₂ can be used onsite or in new products, or stored long term to prevent release.

  • A greenhouse gas that is naturally found in the atmosphere. Its atmospheric concentration has been increasing due to human activities, leading to warming and climate impacts.

  • Total GHG emissions resulting from a particular action, material, technology, or sector.

  • Amount of GHG emissions released per activity or unit of production. 

  • A marketplace where carbon credits are purchased and sold. One carbon credit represents activities that avoid, reduce, or remove one metric ton of GHG emissions.

  • A colorless, odorless gas released during the incomplete combustion of fuels containing carbon. Carbon monoxide can harm health and be fatal at high concentrations.

  • The time it takes for the emissions reduction from a measure to equal the emissions invested in implementing the measure.

  • Activities or technologies that pull CO₂ out of the atmosphere, including enhancing natural carbon sinks and deploying engineered sinks.

  • Long-term storage of carbon in soils, sediment, biomass, oceans, and geologic formations after removal of CO₂ from the atmosphere or CO₂ capture from industrial and power generation processes.

  • carbon capture and storage

  • carbon capture, utilization, and storage

  • A binding ingredient in concrete responsible for most of concrete’s life-cycle emissions. Cement is made primarily of clinker mixed with other mineral components.

  • methane

  • Gases or particles that have a planet-warming effect when released to the atmosphere. Some climate pollutants also cause other forms of environmental damage.

  • A binding ingredient in cement responsible for most of the life-cycle emissions from cement and concrete production.

  • carbon monoxide

  • Neighbors, volunteer organizations, hobbyists and interest groups, online communities, early adopters, individuals sharing a home, and private citizens seeking to support the solution.

  • A solution that potentially lowers the benefit of another solution through reduced effectiveness, higher costs, reduced or delayed adoption, or diminished global climate impact.

  • A farming system that combines reduced tillage, cover crops, and crop rotations.

  • carbon dioxide

  • A  measure standardizing the warming effects of greenhouse gases relative to CO₂. CO₂-eq is calculated as quantity (metric tons) of a particular gas multiplied by its GWP.

  • carbon dioxide equivalent

  • Parts of plants, such as stalks and stubble, left in a field after harvest.

  • The process of cutting greenhouse gas emissions (primarily CO₂) from a particular sector or activity.

  • A solution that works slower than gradual solutions and is expected to take longer to reach its full potential.

  • Microbial conversion of nitrate into inert nitrogen gas under low-oxygen conditions, which produces the greenhouse gas nitrous oxide as an intermediate compound.

  • Greenhouse gas emissions produced as a direct result of the use of a technology or practice.

  • Ability of a solution to reduce emissions or remove carbon, expressed in CO₂-eq per installed adoption unit. Effectiveness is quantified per year when the adoption unit is cumulative over time.

  • Greenhouse gas emissions accrued over the lifetime of a material or product, including as it is produced, transported, used, and disposed of.

  • Solutions that work faster than gradual solutions, front-loading their impact in the near term.

  • Methane produced by microbes in the digestive tracts of ruminant livestock, such as cattle, sheep and goats.

  • U.S. Environmental Protection Agency

  • environmental, social, and governance

  • exchange-traded fund

  • A process triggered by an overabundance of nutrients in water, particularly nitrogen and phosphorus, that stimulates excessive plant and algae growth and can harm aquatic organisms.

  • Electric vehicle

  • An ecological process that releases water into the atmosphere as a gas from soil and ice (evaporation) and plants (transpiration).

     

  • The scientific literature that supports our assessment of a solution's effectiveness.

  • A group of human-made molecules that contain fluorine atoms. They are potent greenhouse gases with GWPs that can be hundreds to thousands times higher than CO₂.

  • Food and Agriculture Organization of the United Nations

  • Raw input material in manufacturing, processing, and waste disposal.

  • food loss and waste

  • Food discarded during pre-consumer supply chain stages, including production, harvest, and processing.

  • Food discarded at the retail and consumer stages of the supply chain.

  • Combustible materials found in Earth's crust that can be burned for energy, including oil, natural gas, and coal. They are formed from decayed organisms through prehistoric geological processes.

  • A group of countries representing the majority of the world's population, trade, and GDP. There are 19 member countries plus the European Union and the African Union

  • greenhouse gas

  • gigajoule or billion joules

  • The glass layers or panes in a window.

  • A measure of how effectively a gas traps heat in the atmosphere relative to CO₂. GWP converts greenhouse gases into CO₂-eq emissions based on their 20- or 100-year impacts.

  • A solution that has a steady impact so that the cumulative effect over time builds as a straight line. Most climate solutions fall into this category.

  • Yard and garden trimmings.

  • A gas that traps heat in the atmosphere, contributing to climate change.

  • metric gigatons or billion metric tons

  • global warming potential

  • hectare

  • household air pollution

  • Number of years a person is expected to live without disability or other limitations that restrict basic functioning and activity.

  • A unit of land area comprising 10,000 square meters, roughly equal to 2.5 acres.

  • Hybrid electric car

  • hydrofluorocarbon

  • hydrofluoroolefin

  • Particles and gases released from use of polluting fuels and technologies such as biomass cookstoves that cause poor air quality in and around the home.

  • Organic compounds that contain hydrogen and carbon.

  • Human-made F-gases that contain hydrogen, fluorine, and carbon. They typically have short atmospheric lifetimes and GWPs hundreds or thousands times higher than CO₂. 

  • Human-made F-gases that contain hydrogen, fluorine, and carbon, with at least one double bond. They have low GWPs and can be climate-friendly alternatives to HFC refrigerants.

  • internal combustion engine

  • Greenhouse gas emissions produced as a result of a technology or practice but not directly from its use.

  • Device used to power vehicles by the intake, compression, combustion, and exhaust of fuel that drives moving parts.

  • The annual discount rate that balances net cash flows for a project over time. Also called IRR, internal rate of return is used to estimate profitability of potential investments.

  • Individuals or institutions willing to lend money in search of a return on their investment.

  • Intergovernmental Panel on Climate Change

  • Indigenous People’s Land

  • Integrated pest management.

  • internal rate of return

  • International Union for Conservation of Nature

  • A measure of energy

  • Definition to come

  • International agreement adopted in 2016 to phase down the use of high-GWP HFC F-gases over the time frame 2019–2047.

  • International agreement adopted in 2016 to phase down the use of high-GWP HFC F-gases over the time frame 2019–2047.

  • A measure of energy equivalent to the energy delivered by 1,000 watts of power over one hour.

  • kiloton or one thousand metric tons

  • kilowatt-hour

  • A land-holding system, e.g. ownership, leasing, or renting. Secure land tenure means farmers or other land users will maintain access to and use of the land in future years.

  • Gases, mainly methane and CO₂, created by the decomposition of organic matter in the absence of oxygen.

  • leak detection and repair

  • Regular monitoring for fugitive methane leaks throughout oil and gas, coal, and landfill sector infrastructure and the modification or replacement of leaking equipment.

  • Relocation of emissions-causing activities outside of a mitigation project area rather than a true reduction in emissions.

  • The rate at which solution costs decrease as adoption increases, based on production efficiencies, technological improvements, or other factors.

  • Percent decrease in costs per doubling of adoption.

  • landfill gas

  • Greenhouse gas emissions from the sourcing, production, use, and disposal of a technology or practice.

  • low- and middle-income countries

  • liquefied petroleum gas

  • A measure of the amount of light produced by a light source per energy input.

  • marginal abatement cost curve

  • Livestock grazing practices that strategically manage livestock density, grazing intensity, and timing. Also called improved grazing, these practices have environmental, soil health, and climate benefits, including enhanced soil carbon sequestration.

  • A tool to measure and compare the financial cost and abatement benefit of individual actions based on the initial and operating costs, revenue, and emission reduction potential.

  • A greenhouse gas with a short lifetime and high GWP that can be produced through a variety of mechanisms including the breakdown of organic matter.

  • A measure of mass equivalent to 1,000 kilograms (~2,200 lbs).

  • million hectares

  • Soils mostly composed of inorganic materials formed through the breakdown of rocks. Most soils are mineral soils, and they generally have less than 20% organic matter by weight.

  • A localized electricity system that independently generates and distributes power. Typically serving limited geographic areas, mini-grids can operate in isolation or interconnected with the main grid.

  • Reducing the concentration of greenhouse gases in the atmosphere by cutting emissions or removing CO₂.

  • Percent of trips made by different passenger and freight transportation modes.

  • Marine Protected Area

  • Municipal solid waste

  • megaton or million metric tons

  • Materials discarded from residential and commercial sectors, including organic waste, glass, metals, plastics, and paper and cardboard.

  • square meter kelvins per watt (a measure of thermal resistance, also called R-value)

  • A commitment from a country to reduce national emissions and/or sequester carbon in alignment with global climate goals under the Paris Agreement, including plans for adapting to climate impacts.

  • A gaseous form of hydrocarbons consisting mainly of methane.

  • Chemicals found in nature that are used for cooling and heating, such as CO₂, ammonia, and some hydrocarbons. They have low GWPs and are ozone friendly, making them climate-friendly refrigerants.

  • Microbial conversion of ammonia or ammonium to nitrite and then to nitrate under aerobic conditions.

  • A group of air pollutant molecules composed of nitrogen and oxygen, including NO and NO₂.

  • A greenhouse gas produced during fossil fuel combustion and agricultural and industrial processes. N₂O is hundreds of times more potent than CO₂ at trapping atmospheric heat, and it depletes stratospheric ozone.

  • Social welfare organizations, civic leagues, social clubs, labor organizations, business associations, and other not-for-profit organizations.

  • A material or energy source that relies on resources that are finite or not naturally replenished at the rate of consumption, including fossil fuels like coal, oil, and natural gas.

  • nitrogen oxides

  • nitrous oxide

  • The process of increasing the acidity of seawater, primarily caused by absorption of CO₂ from the atmosphere.

  • An agreement between a seller who will produce future goods and a purchaser who commits to buying them, often used as project financing for producers prior to manufacturing.

  • Protected Area

  • Productive use of wet or rewetted peatlands that does not disturb the peat layer, such as for hunting, gathering, and growing wetland-adapted crops for food, fiber, and energy.

  • Airborne particles composed of solids and liquids.

  • A measure of transporting one passenger over a distance of one kilometer.

  • The longevity of any greenhouse gas emission reductions or removals. Solution impacts are considered permanent if the risk of reversing the positive climate impacts is low within 100 years.

  • A mixture of hydrocarbons, small amounts of other organic compounds, and trace amounts of metals used to produce products such as fuels or plastics.

  • Plug-in hybrid electric car

  • Private, national, or multilateral organizations dedicated to providing aid through in-kind or financial donations.

  • An atmospheric reaction among sunlight, VOCs, and nitrogen oxide that leads to ground-level ozone formation. Ground-level ozone, a component of smog, harms human health and the environment.

  • passenger kilometer

  • particulate matter

  • Particulate matter 2.5 micrometers or less in diameter that can harm human health when inhaled.

  • Elected officials and their staff, bureaucrats, civil servants, regulators, attorneys, and government affairs professionals.

  • System in a vehicle that generates power and delivers it to the wheels. It typically includes an engine and/or motor, transmission, driveshaft, and differential.

  • Purchase Power Agreement.

  • People who most directly interface with a solution and/or determine whether the solution is used and/or available. 

  • The process of converting inorganic matter, including carbon dioxide, into organic matter (biomass), primarily by photosynthetic organisms such as plants and algae.

  • Defined by the International Union for the Conservation of Nature as "A clearly defined geographical space, recognised, dedicated and managed, through legal or other effective means, to achieve the long-term conservation of nature with associated ecosystem services and cultural values". References to PAs here also include other effective area-based conservation measures defined by the IUCN. 

  • Long-term contract between a company (the buyer) and a renewable energy producer (the seller).

  • A situation in which improvements in efficiency or savings lead to consumers increasing consumption, partially or fully offsetting or exceeding the emissions or cost benefits.

  • Renewable Energy Credit.

  • Renewable Energy Certificate.

  • Chemical or mixture used for cooling and heating in refrigeration, air conditioning, and heat pump equipment. Refrigerants absorb and release heat as they move between states under changing pressure.

  • A group of approaches to farming and ranching that emphasizes enhancing the health of soil by restoring its carbon content and providing other benefits to the farm and surrounding ecosystem.

  • A solution that can increase the beneficial impact of another solution through increased effectiveness, lower costs, improved adoption, enhanced global climate impact, and/or other benefits to people and nature.

  • A material or energy source that relies on naturally occuring and replenishing resources such as plant matter, wind, or sunlight.

  • A market-based instrument that tracks ownership of renewable energy generation.

  • Very large or small numbers are formatted in scientific notation. A positive exponent multiplies the number by powers of ten; a negative exponent divides the number by powers of ten.

  • Seasonal coefficient of performance

  • Sustainable Development Goals

  • A measure of average heat pump efficiency over the heating season.

  • A practice in which multiple utility companies own and operate high-voltage power lines, with both paying costs and receiving benefits.

  • A practice in which multiple utility companies own and operate high-voltage power lines, sharing both costs and benefits.

  • Small-scale family farmers and other food producers, often with limited resources, usually in the tropics. The average size of a smallholder farm is two hectares (about five acres).

  • soil organic carbon

  • Carbon stored in soils, including both organic (from decomposing plants and microbes) and inorganic (from carbonate-containing minerals).

  • Carbon stored in soils in organic forms (from decomposing plants and microbes). Soil organic carbon makes up roughly half of soil organic matter by weight.

  • Biologically derived matter in soils, including living, dead, and decayed plant and microbial tissues. Soil organic matter is roughly half carbon on a dry-weight basis.

  • soil organic matter

  • sulfur oxides

  • sulfur dioxide

  • How quickly a climate solution physically affects the atmosphere after it is deployed.

  • Climate regions between latitudes 23.4° to 35° above and below the equator characterized by warm summers and mild winters.

  • A polluting gas produced primarily from burning fossil fuels and industrial processes that directly harms the environment and human health.

  • A group of gases containing sulfur and oxygen that predominantly come from burning fossil fuels. They contribute to air pollution, acid rain, and respiratory health issues.

  • Processes, people, and resources involved in producing and delivering a product from supplier to end customer, including material acquisition.

  • Sport utility vehicle

  • metric tons

  • Technology developers, including founders, designers, inventors, R&D staff, and creators seeking to overcome technical or practical challenges.

  • Climate regions between 35° to 50° above and below the equator characterized by moderate mean annual temperatures and distinct seasons, with warm summers and cold winters.

  • A measure of energy equivalent to the energy delivered by one trillion (1,000,000,000,000) watts of power over one hour. 

  • A measure of how well a material prevents heat flow, often called R-value or RSI-value for insulation. A higher R-value means better thermal performance.

  • Individuals with an established audience for their work, including public figures, experts, journalists, and educators.

  • Charge for disposal of materials paid to facility operators. Fees can be charged per ton of waste disposed or based on economic indicators like the Consumer Price Index (CPI).

  • Low-latitude (23.4°S to 23.4°N) climate regions near the Equator characterized by year-round high temperatures and distinct wet and dry seasons.

  • United Nations

  • United Nations Environment Programme

  • Self-propelled machine for transporting passengers or freight on roads.

  • A measure of one vehicle traveling a distance of one kilometer.

  • vehicle kilometer

  • volatile organic compound

  • Gases made of organic, carbon-based molecules that are readily released into the air from other solid or liquid materials. Some VOCs are greenhouse gases or can harm human health.

  • watt (a measure of power or energy transfer.)

  • A measure of power equal to one joule per second.

  • A subset of forest ecosystems that may have sparser canopy cover,  smaller-stature trees, and/or trees characterized by basal branching rather than a single main stem.

  • year

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