Sunset View of Elder Park, the Riverside Precinct and the Torrens Lake, Adelaide, South Australia.

As part of Adelaide's commitment to net zero by 2025, the city is powering its municipal operations with 100% renewable energy, making buildings more energy efficient, investing in energy storage technology, harnessing biogas from wastewater treatment plants, promoting the uptake of hybrid and electric vehicles, and promoting more cycling and walking.

Credit: Artie Photography (Artie Ng) / Getty Images

Efficiency

Call to action:

Cut energy and materials use to reduce emissions, stabilize the climate, improve quality of life, and benefit economies and ecosystems.

Energy efficiency has been called “the first fuel”: the fuel that doesn’t have to be used at all. Reducing total energy supply (and therefore demand) by ten percent by 2030 is necessary to reach net zero carbon by 2050. We can achieve this goal by decreasing the amount of energy and material needed for buildings, transport, agriculture, industry, and the Internet, but the pace of improvement needs to double. One study showed that with renewables, the UK could reduce energy demand by fifty percent by 2050 while bettering quality of life. Technical gains, such as solar panel innovations, smart buildings, and LED lighting, have greatly enhanced energy and material efficiency. Design changes can increase efficiency just as much. In addition, behavioral change– both individual and collective– is needed so that technical gains can keep pace with growing demand. Behavioral change in developed countries can have five times the impact of behavioral change in countries with less access to energy. By building energy and material efficiency into our technology, designs, and decisions, we can improve lives as we keep the climate habitable.

Nexus Rating System^Beta

Solutions to the climate emergency have unique social and environmental effects, positive and negative. To develop a broader understanding of the solutions in Nexus, we rate each solution on five criteria.

Sources for each Nexus are graded numerically (-3 through 10), and the average is displayed as a letter grade. You can explore each source in depth by clicking “view sources” below. For more information, see our Nexus Ratings page.

Efficiency

0.00

7.80

Social Justice
Culture
Women
Biodiversity
Carbon

Reference	Social Justice	Culture	Women	Biodiversity	Carbon
Energy demand reduction options for meeting national zero-emission targets in the United Kingdom	8.0				7.0
Energy Efficiency: The Clean Facts	9.0
A Vision for Clean Cooking Access for All	9.0
Energy efficiency as energy justice: addressing racial inequities through investments in people and places	9.0
How Does Energy Efficiency Create Jobs?	8.0
Understanding the True Benefits of Both Energy Efficiency and Job Creation	8.0
Energy efficiency jobs and the recovery	9.0
Economic and Employment Impacts of Energy Efficiency	9.0
Clean, Efficient Energy Can Boost Resilience in Marginalized Communities	8.0
Providing Access to Clean Cooking: Good for the Health and the Climate	8.0
The climate and health benefits from intensive building energy efficiency improvements					7.0
IA: Multiple Benefits of Energy Efficiency, Emissions savings					9.0
IEA: Energy Efficiency 2022					7.0
Energy Efficiency Can Slash Emissions and Get US Halfway to Climate Goals					9.0
	8.5	0.0	0.0	0.0	7.8

Action Items

Individuals

Learn the drivers of energy demand and the levers that lower energy intensity. Energy intensity, often defined as the amount of energy per unit of gross domestic product, is falling. But electricity demand is rising worldwide, primarily driven by five technologies—electric vehicles, heat pumps, electrolyzers for green hydrogen, data centers, and air conditioning. The first three are essential to transition away from fossil fuels, and all need to be as efficient as possible to offset the growth in demand. Levers for improving total energy efficiency include electrification and improving industrial and building practices. Reducing our demand for energy and materials not only helps cut emissions, it saves lives by decreasing air pollution.

Focusing on technical efficiency alone is insufficient because of the Jevons paradox, or rebound effect, in which greater efficiency leads to increased resource use. In 1865, William Stanley Jevons noticed that as steam engines used coal more efficiently, more coal was used, not less, because more could be done with a ton of coal. This paradox arises in many areas: electric car users drive farther than those that require gas; LED lighting is much more efficient than conventional, so it is used for enormous Christmas displays. Our individual and collective decisions are thus essential to driving down energy demand.
Switching from fossil fuels to renewables is more efficient because burning fossil fuels for energy creates a lot of waste heat. Electric vehicles and heat pumps are much more efficient than internal combustion engines and gas boilers, and renewables are more efficient than fossil fuel energy production. See Electrify Everything Nexus.
About thirty percent of people globally rely on inefficient open fires that lead to deforestation, produce black carbon, pollute homes, and are dangerous. Clean cookstoves solve all these problems while reducing energy needs by nearly sixty percent. See Clean Cookstoves Nexus.

Buy electric vehicles (EVs) rather than internal combustion engines (ICEs), and buy the smallest car that fits your needs. EVs convert energy into motion more efficiently than ICEs, so a comparably sized EV requires less energy than an ICE. Pickups and SUVs are available, as well as sedans. But larger EVs require more electricity, larger batteries, and more material (so more mining) than smaller ones. The U.S. Department of Energy rates the energy efficiency of EVs, and several sites rate the top 10 or 20 vehicles in the U.S. and elsewhere. See Electric Vehicles Nexus.

Enroll in a demand response program if your utility offers it, and time your energy use for off-peak times. Demand response programs reward energy reduction during peak energy events, usually without penalty if you do not reduce energy. The energy savings from these programs can reduce the need for fossil-fuel peaker plants and prevent blackouts. Charge laptops, phones, and anything else with a battery overnight or in the morning, and pre-cool your house on cool summer mornings to reduce afternoon AC use.

Make energy-reduction decisions ordinary. Simple measures helped reduce Italy’s and Germany’s reliance on Russian fossil fuels during the 2022 energy crisis. Setting your thermostat to 68°F in winter (lower at night) and 78°F in summer (higher when you’re away) can reduce your demand without sacrificing comfort, especially if you use fans to keep air moving. Line-drying clothes saves energy and helps clothes last longer. According to the Department of Energy, switching all the planet’s lights (including fluorescent) to LEDs could save 569 TWh of energy annually. Driving the speed limit and minimizing aggressive acceleration and braking are safer and more energy efficient.

Build good internet and gaming habits. Digital technology is responsible for an increasing share of greenhouse gas emissions, and personal digital use is responsible for about a third of that. Decluttering your email, reducing your email newsletter subscriptions, minimizing device upgrades, and not streaming music (or especially videos you’re not paying attention to) can all help. Video games are one of the most energy-intensive home uses of electricity, and consoles use a surprising amount of materials. Reducing cloud gaming, shutting down your computer or console when not in use, and using efficient hardware all help.

If you use cryptocurrency, choose a proof-of-stake instead of a proof-of-work currency. Both types of crypto require electricity to function, but proof-of-stake currencies like Ethereum require less than one ten-thousandth the energy of proof-of-work currencies like Bitcoin–which pulls more power than all the refrigerators in the U.S.

Groups

Homeowners and Landlords

Replace appliances with electrical instead of gas appliances—and buy the most efficient ones possible. Gas appliances create waste heat and noxious fumes, which are bad for efficiency, the environment, and your health. Replace gas heaters and traditional air conditioners with heat pumps, gas cook stoves with induction stoves, and gas water heaters with electric, solar, or heat pump types. Many governments have labeling programs, such as Energy Star in the US, to help you find the most efficient models, and they may be cheaper than less efficient appliances. Your utility may also offer assistance. See Heat Pumps Nexus, Electrify Everything Nexus, and Buildings Nexus.

Make sure your building is weatherproofed, insulated, and has efficient windows. Caulking, insulating, and using double- or even triple-paned windows reduce heating and AC bills—and good windows keep the building quieter.

When you replace your roof, make it a cool one. Cool roofs are typically light-colored. They reflect sunlight and shed absorbed heat efficiently. Not only do they cool individual houses, but they can also reduce the heat island effect. The Million Cool Roofs Challenge demonstrated up to 20°F cooler inside air in Indonesia.

Farmers and Ranchers

Manage fertilizer and cattle feed for maximum growth and minimum emissions. Overuse of fertilizer increases nitrous oxide (N2O), a greenhouse gas 265 times more powerful than CO2 that also depletes the ozone layer. Agricultural activities account for nearly eighty percent of US human N2O emissions, which are increasing at a rate in line with the worst-case warming scenario.

Improve nitrogen fertilizer efficiency to increase crop yields with less fertilizer. The top way to reduce N2O emissions from crops is fertilizer management, with irrigation and tillage next. Adding nitrogen when crops are in the field (instead of pre-fertilizing), sidebanding instead of broadcasting, and deep fertilization made a clear difference. Techniques include increasing soil organic matter, using slow-release fertilizer, and using micro-irrigation so the soil isn’t saturated. Applying less fertilizer more often may also help.
Manage cattle protein intake to reduce N2O from manure. Cattle excrete most of the nitrogen in their feed, making them an important source of N2O. An optimal, low level of crude protein reduces their N2O impact. Maintaining healthy, diverse pasture and silvopasture and encouraging dung beetles also reduces N2O. See Silvopasture Nexus.

Update animal housing, irrigation pumps, and cooling equipment to increase energy efficiency. US National Resource Conservation Service has calculators to help you see how much you could save from renovating.

Try an electric tractor. Monarch, Kubota, and New Holland manufacture small-to-midsize all-electric tractors. Monarch’s has bidirectional charging, serving as a portable generator. John Deere is ramping up to produce a range of tractors and construction equipment. CNH is producing an electric front-loader.

Companies

Utilities and Community Choice Aggregators

Implement demand response programs and other load-shifting strategies. Demand response programs and load shifting smooth the “duck curve” (the timing mismatch between renewable supply and energy demand) and reduce the need for fossil fuel peaker plants. Time-of-use pricing charges more for more expensive/less renewable energy. Load shifting moves energy demand to times when renewable energy is more abundant. Load shifting should take efficiency into account to reduce emissions since some loads are actually less efficient at certain times.

India is a leader in Asia in using time-of-use pricing to shift energy demand to high-solar hours, reducing night-time fossil-fuel energy and the potential for blackouts.
California uses time-of-use pricing and both supply-side and demand-side methods to manage the duck curve. On Sept. 6, 2022, demand response programs, including emergency texts to residential customers, made news for an instantaneous reduction in peak energy loads that prevented blackouts in California during a record heat wave.

Make grids and infrastructure more flexible and robust. Streamlined grid tie-ins must keep pace with solar adoption and grid-scale storage employed to decrease curtailment (reducing generation so supply matches demand). Smart meters, thermostats, appliances, grid-interactive water heaters, and smart/bidirectional EV chargers all make energy demand more flexible and reduce peak loads. See Energy Storage Nexus.

A connect-and-manage approach to grid tie-ins, which accepts a risk of curtailment to speed the tie-in, has enabled Texas to be the US leader in solar.
In Australia, a decommissioned coal plant is being converted to the Watarah Super Battery, which stores 1680 MWh of electricity, and a 2000 MWh battery is under construction.
China leads the world in pumped-hydro storage, with over 50 gigawatts and more under construction. See Hydropower Nexus.
Indonesia is rolling out 79 million smart meters for a cost similar to recalibrating faulty older meters.
PG&E is piloting grid-interactive water heaters, which shift load away from California’s summer evening peak more effectively than smart thermostats.
Sonoma Clean Power’s GridSavvy program incentivizes householders to adopt smart appliances and EV chargers.

Use virtual power plants (VPPs) to coordinate energy use among homes and businesses with smart thermostats, batteries, EVs, solar panels, and appliances. VPPs are another way to minimize the use of fossil-fuel peaker plants and their emissions and costs.

In California, Marin Clean Energy is rehabilitating abandoned homes in preparation for a VPP, and Sacramento Municipal Utility District is aggregating residences with solar and batteries, with funding for low-income participants.
Utilities in Texas, Vermont, and Massachusetts are all implementing VPPs.

Consider converting natural gas lines to a geothermal network. The conversion costs are comparable to replacing aging gas lines, creating highly efficient heating and cooling and a post-gas future for utilities. Twenty-five utilities, including Vermont Gas, are exploring geothermal in the Utility Networked Geothermal Collaborative, and Eversource has completed a geothermal neighborhood in Massachusetts. See Geothermal Nexus.

Data Centers

Prioritize energy and water efficiency. Data center energy use is on track to double between 2022 and 2026, largely driven by artificial intelligence (AI). It puts both Google and Microsoft on paths to miss their 2030 energy goals by significant margins. Jevons’ paradox is part of the problem: efficient methods for AI have been used not to reduce energy demand but to increase AI computing. Data center cooling also uses large amounts of water and may use as much water as Denmark by 2027.

Implement AI wisely. Training is energy-intensive, so using an existing model cuts the total energy demand. Some fields, like medicine, genuinely benefit from AI, but AI-generated blog posts are of dubious value. Specializing requires less data processing and makes the AI more competent.
Optimize computing load. Consolidating computing for high workloads and distributing it for low workloads can reduce energy use by ten to thirty percent and reduce cooling needs.
Know your power use and constrain it. Capping the amount of power drawn by GPUs slows computing slightly but greatly reduces both energy and cooling demand.
Monitor your carbon footprint and use infrastructure management to reduce it. Co-locating renewable energy with the data center reduces emissions, but in order to improve energy intensity, efficient servers and cooling equipment, consolidation, virtualization, and lifecycle management must be used.

Construction

Construct grid-interactive efficient buildings. Buildings account for forty percent of energy use in the U.S. and 75% of its electricity. Efficient buildings have lower emissions and higher value—up to a ten percent price premium. Grid-interactive buildings can modify their energy use based on grid signals. If they include battery storage or solar panels, they may act as distributed energy resources supplying a virtual power plant. Grid-interactive building technologies integrate efficiency into heating, ventilation, cooling, lighting, and electronics systems, as well as into passive design elements like windows and envelope. They also incorporate building energy management systems that monitor occupancy and energy use to adjust demand. A building management system that lowered energy use by 21%, combined with onsite solar, enabled an Asea Brown Boveri manufacturing facility to be carbon neutral.

Use integrative design for buildings and retrofits. Integrative design plans buildings as whole systems, creating synergies that reduce energy needs by large margins and streamline construction. See Buildings Nexus.

A biomimicry building design avoided using air conditioning entirely in Zimbabwe by integrating ventilation and envelope design. This saved ten percent on construction costs and made the building resilient to power outages.
Integrative design saved 38% of energy and $4.4 million in utility costs for the Empire State Building's retrofit.

Industry

Maintain heat exchangers and replace aging heat exchangers with efficient ones. Poorly maintained heat exchangers—in data centers, facilities, and many buildings’ heating and cooling systems—may account for up to 2.5% of greenhouse gas emissions. Exchanger design can facilitate maintenance and increase efficiency, and there are numerous methods for cleaning them.

Decarbonize cement through materials efficiency and substitution. Cement and concrete produce CO2 mainly through heating limestone to drive off carbon and produce clinker. Multiple potential solutions exist, including building design, concrete reuse, substituting fly ash or other materials for clinker, and reformulating cement. See Green Cement Nexus.

Explore promising technologies for decarbonizing steel. Low-temperature iron ore refining and using hydrogen or electrolysis to reduce iron have potential and are starting to be used at scale. Increasing the use of scrap iron to make steel is a well-established way to make it more energy-efficient.

Use heat pumps for low-temperature chemical reactions. Heat pumps can be used for reactions up to 350° F, and the payback time is under two years in many chemical processes.

Integrate variable-speed motor upgrades with high-efficiency replacement motors. Improving industrial motor efficiency worldwide could cut global emissions by ten percent—and pay for itself with lower energy bills. Although the highest-efficiency motors are more expensive, they save far more than their price in energy. Variable-speed motors that adjust to load are more efficient and last longer.

Governance

Institute ambitious policies that prioritize efficiency. Public policy should aim for an improvement (reduction) in energy intensity of four percent per year, doubling current improvement. Energy efficiency increases energy security, strengthens macroeconomics, reduces the need to build out energy infrastructure, and makes it easier to respond to disaster. It can also increase public revenues and decrease expenditures, especially when it leads to job creation. The International Energy Agency (IEA) has a policy toolkit with ten best practices and recommendations for regulation, information, and incentives in five sectors.

Use regulations to reduce emissions and increase efficiency. Regulation is second only to business opportunity in driving corporate behavior, and well-thought-out regulation provides businesses with a clear direction and a stable environment that encourages investment in green technology.

New Securities Exchange Commission regulations in the US and Europe’s Sustainable Finance Disclosure Regulation require emissions disclosure.
Interconnection standards and net metering requirements promote renewable power facilities and household solar, while feed-in tariffs and renewable energy portfolios incentivize renewable power.
Decoupling utility revenues from the amount of energy sold prevents perverse incentives to increase energy use and ensures utilities can thrive with more efficiency.

Invest in clean energy and efficiency. Renewable energy, public transit, and low-carbon vehicles are the top three investments by governments. The United States’ Inflation Reduction Act accounts for nearly 25% of clean energy investment globally, with Germany next. The IEA provides a browser with over 1600 financial policies.

Point the way to efficiency with public education campaigns. Messaging should connect efficiency to national culture, be clear and consistent, and help citizens get support for energy-efficient actions.

France’s “Sobrieté Energique” campaign reduced energy use by 12% through voluntary measures, including reductions by local governments and a powerfully symbolic early lights-out for the Eiffel Tower.
Finland’s Down a Degree program, emphasizing Finnish toughness and cold tolerance, led 95% of Finns who saw the program to take at least one energy-saving measure. Engaging with partners was critical to the campaign’s success.
Ireland’s Reduce Your Use campaign provides simple steps for maximum impact along with guides to government incentives.

Establish incentive and investment programs to help businesses and consumers produce and adopt efficient buildings and equipment.

An incentive program for heat pumps in chilly Maine has surpassed its goal and kept households warm for much lower heating bills. The program includes rebates and information on federal tax credits. Canada provides grants to low- to medium-income homeowners that effectively make heat pump installation free.
France offers a scrappage bonus for those who buy low-emission vehicles and scrap their old fossil-fuel burners.
In the U.S., the Inflation Reduction Act includes federal tax credits for investing in facilities that produce essentials for renewable energy, refitting heat systems, manufacturing solar components and batteries, or refining critical minerals.
India is jumpstarting its battery manufacturing through a competitive bidding process for incentives.

Set minimum energy performance standards (MEPS) and combine them with labeling. MEPs have been called “one of the most widespread and effective tools of energy efficiency policy,” especially when combined with labels that enable consumers to compare easily. Cross-border cooperation enables countries to set standards at lower costs, with greater consistency for manufacturers and consumers. Ambitious policies have the most impact and are attainable: all end-user technologies have models that match or exceed the efficiency needed to reach net zero by 2050.

Exemplary MEPS, a policy browser, and modeling tools are available at CLASP.

Municipalities

Change streetlights to LEDs with smart features. LEDs save Los Angeles nearly forty percent in electricity use and even more in costs. They also reduce maintenance, light pollution, and crimes like burglary and vandalism. Smart lighting can further reduce costs by matching brightness to time of night or using motion sensors.

Partner with utilities to create district heating and cooling. District heating is a well-established technology that creates economies of scale. Different locales can use different methods for space heating and/or cooling. HEET provides a municipal toolkit.

Framingham, Massachusetts, partnered with Eversource Energy to convert gas lines to geothermal for much more efficient—and much less dangerous—heating and cooling for 36 buildings. Other towns in Massachusetts are creating geothermal networks.
Gujarat International Finance-Tech City uses cogeneration to prechill water and store it for release at peak times, reducing energy needs by nearly fifty percent.
Kensa Group retrofitted 273 social housing flats in the UK with a network of heat pumps, replacing aging electric heating.

Update building codes. Efficient buildings powerfully reduce energy intensity and can reduce the heat island effect.

The U.S. Department of Energy offers grants to support building code updates.
The Institute for Market Transformation has tools for building code updating and compliance.