What are the solutions?

Project Drawdown identified 100 climate change solutions and ranked them based on their potential to reduce greenhouse gases.

All of the solutions should be implemented, as no single solution will be enough.

Swipe and tap the solutions to explore.

#27 District Heating

Buildings and Cities

With district systems, a central plant channels hot and/or cool water via a network of pipes to many buildings — heating and cooling them more efficiently.

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District Heating

Buildings and Cities

Rank and results by 2050 #27

Reduced CO2: 9 gigatons
Net cost (Billions US$): $457.10
Net operational savings: $3,543.50 billion
What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

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Impact:

By replacing existing stand-alone water- and space-heating systems, district heating can reduce carbon dioxide emissions by 9.4 gigatons by 2050 and save $3.5 trillion in energy costs. Our analysis estimates current adoption at .01 percent of heating demand, growing to 10 percent over the next thirty years. While natural gas is currently the most prevalent fuel source for district heating facilities, we model the impact only of alternative sources such as geothermal and solar thermal energy that will become more prevalent over time.

#31 Insulation

Buildings and Cities

Insulation is one of the most cost-effective ways to make buildings more energy efficient — both in new construction and through retrofitting older buildings.

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Insulation

Buildings and Cities

Rank and results by 2050 #31

Reduced CO2: 8 gigatons
Net cost (Billions US$): $3,655.92
Net operational savings: $2,513.33 billion
What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

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Impact:

Retrofitting buildings with insulation is a cost-effective solution for reducing energy required for heating and cooling. If 54 percent of existing residential and commercial buildings install insulation, 8.3 gigatons of emissions can be avoided at an implementation cost of $3.7 trillion. Over thirty years, net savings could be $2.5 trillion. However, insulation measures can last one hundred years or more, realizing lifetime savings in excess of $4.2 trillion.

#33 LED Lighting (Household)

Buildings and Cities

By transferring most of their energy use into creating light — rather than heat, like older technologies — LEDs reduce electricity consumption and air-conditioning loads.

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LED Lighting (Household)

Buildings and Cities

Rank and results by 2050 #33

Reduced CO2: 8 gigatons
Net cost (Billions US$): $323.52
Net operational savings: $1,729.54 billion
What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

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Impact:

Our analysis assumes that LEDs will become ubiquitous by 2050, encompassing 90 percent of the household lighting market. As LEDs replace less-efficient lighting, 7.8 gigatons of carbon dioxide emissions could be avoided in residences. Additional gains, not counted here, will come from replacing off-grid kerosene lighting with solar-LED technology.

#42 Heat Pumps

Buildings and Cities

Heat pumps transfer heat from a cold space to a hot one. Highly efficient, they can dramatically lower building energy use for heating and cooling.

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Heat Pumps

Buildings and Cities

Rank and results by 2050 #42

Reduced CO2: 5 gigatons
Net cost (Billions US$): $118.71
Net operational savings: $1,546.66 billion
What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

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Impact:

Heating and cooling of residential and commercial building space requires more than 13,000 terawatt-hours of energy and is estimated to increase to more than 18,000 terawatt-hours by 2050. This energy use comes from on-site fuel combustion and electricity-based systems — from gas furnaces to air-conditioning units. High-efficiency heat pumps reduce fuel consumption to zero and use less electricity to generate heating and cooling. Current adoption is low at .02 percent of the market, but we estimate rapid growth as costs continue to decrease by up to 25 percent by 2050. For a cost of $119 billion in addition what would be spent on conventional technologies, operating savings could reach $1.5 trillion over three decades and $3.5 trillion over the technology’s lifetime. Emissions reductions in this scenario come to 5.2 gigatons of carbon dioxide.

#44 LED Lighting (Commercial)

Buildings and Cities

Lighting accounts for 15 percent of global electricity use. LEDs (light emitting diodes) require less energy and create less waste heat than other bulbs.

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LED Lighting (Commercial)

Buildings and Cities

Rank and results by 2050 #44

Reduced CO2: 5 gigatons
Net cost (Billions US$): $-205.05
Net operational savings: $1,089.63 billion
What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

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Impact:

Our analysis assumes that LEDs will become ubiquitous by 2050, encompassing 82 percent of commercial lighting. As LEDs replace less-efficient lighting, 5.0 gigatons of carbon dioxide emissions could be avoided in commercial buildings.

#45 Building Automation

Buildings and Cities

Building automation systems serve as the 'brain' of large commercial buildings. Controlling temperature, lighting, and more, they can improve energy efficiency and occupants ' comfort.

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Building Automation

Buildings and Cities

Rank and results by 2050 #45

Reduced CO2: 5 gigatons
Net cost (Billions US$): $68.12
Net operational savings: $880.55 billion
What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

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Impact:

BAS can result in up to 20 percent more efficient heating and cooling and 11.5 percent more efficient energy use for lighting, appliances, etc. Expanding these systems from 34 percent of commercial floor space in 2014 to 50 percent by mid-century — at an added cost of $68 billion—building owners could save $881 billion in operating costs. 4.6 gigatons of carbon dioxide emissions could be avoided.

#54 Walkable Cities

Buildings and Cities

Walkable cities prioritize two feet over four wheels through careful planning and design. As people need to drive less and want to walk more, emissions decrease.

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Walkable Cities

Buildings and Cities

Rank and results by 2050 #54

Reduced CO2: 3 gigatons
Net operational savings: $3,278.24 billion
What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

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Impact:

The six dimensions of the built environment—demand, density, design, destination, distance, and diversity—are all key drivers of walkability. Our analysis focuses on population density as a proxy for walkable neighborhoods. As cities become denser and city planners, commercial enterprises, and residents invest in the “6Ds,” 5 percent of trips currently made by car can be made by foot instead by 2050. That shift could result in 2.9 gigatons of avoided carbon dioxide emissions and reduce costs associated with car ownership by $3.3 trillion.

#57 Smart Thermostats

Buildings and Cities

Thermostats are mission control for heating and cooling homes. Smart thermostats use algorithms and sensors to learn and become more energy efficient over time.

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Smart Thermostats

Buildings and Cities

Rank and results by 2050 #57

Reduced CO2: 3 gigatons
Net cost (Billions US$): $74.16
Net operational savings: $640.10 billion
What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

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Impact:

We project that smart thermostats could grow from .4 percent to 46 percent of households with internet access by 2050. In this scenario, 704 million homes would have them. Reduced energy use could avoid 2.6 gigatons of carbon dioxide emissions. Return on investment is high: smart thermostats can save their owners $640 billion on utility bills by 2050.

#58 Landfill Methane

Buildings and Cities

Landfills are a top source of methane emissions. Instead, landfill methane can be captured, preventing emissions, and used as a fairly clean energy source.

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Landfill Methane

Buildings and Cities

Rank and results by 2050 #58

Reduced CO2: 3 gigatons
Net cost (Billions US$): $-1.82
Net operational savings: $67.57 billion
What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

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Impact:

This solution sits at the bottom of the waste hierarchy. Landfill waste will decline as diets change, waste is reduced, and recycling and composting grow. What cannot, or should not, be combusted in waste-to-energy facilities will reach landfills as a last resort. These solutions will not be adopted globally overnight, so we assume landfill methane capture will continue to play a role. Combusting landfill methane for electricity production can result in emissions reductions equivalent to 2.5 gigatons of carbon dioxide.

#59 Bike Infrastructure

Buildings and Cities

Infrastructure is essential for supporting safe, pleasant, and abundant bicycle use — which can relieve city congestion, improve public health, and reduce emissions from cars.

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Bike Infrastructure

Buildings and Cities

Rank and results by 2050 #59

Reduced CO2: 2 gigatons
Net cost (Billions US$): $-2,026.97
Net operational savings: $400.47 billion
What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

NET COST (billions US $)

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SAVINGS (billions US $)

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Impact:

In 2014, 5.5 percent of urban trips around the world were completed by bicycle. In some cities, bicycle mode share was over 20 percent. We assume a rise from 5.5 percent to 7.5 percent of urban trips globally by 2050, displacing 2.2 trillion passenger-miles traveled by conventional modes of transportation and avoiding 2.3 gigatons of carbon dioxide emissions. By building bike infrastructure rather than roads, municipal governments, and taxpayers can realize $400 billion in savings over thirty years and $2.1 trillion in lifetime savings.

#61 Smart Glass

Buildings and Cities

Compared to walls, windows are inefficient insulators. Smart glass can respond to sunlight and weather, reducing a building's energy load for lighting, heating, and cooling.

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Smart Glass

Buildings and Cities

Rank and results by 2050 #61

Reduced CO2: 2 gigatons
Net cost (Billions US$): $932.30
Net operational savings: $325.10 billion
What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

NET COST (billions US $)

Net cost to implement

SAVINGS (billions US $)

Net savings by 2050

Impact:

Smart glass is an up-and-coming solution with a current adoption in only .004 percent of commercial building space. We assume that growth will occur primarily in the commercial sector in high-income countries and can reach 29 percent of new commercial building space by 2050. The potential energy efficiency from cooling is estimated at 23 percent and lighting at 35 percent. Both will vary depending on local climate and building location. Adopting smart glass can result in 2.2 gigatons of emissions reductions from decreased energy use. The financial cost is high at $932 billion, yielding thirty- year operational savings of $325 billion and lifetime savings of $3.6 trillion.

#71 Water Distribution

Buildings and Cities

Pumping water requires enormous amounts of energy. By minimizing leaks in water-distribution networks — currently wasting 8.6 trillion gallons annually
— both energy and water are saved.

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Water Distribution

Buildings and Cities

Rank and results by 2050 #71

Reduced CO2: 1 gigatons
Net cost (Billions US$): $137.37
Net operational savings: $903.11 billion
What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

NET COST (billions US $)

Net cost to implement

SAVINGS (billions US $)

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Impact:

Modeling only the impact of pressure management and active leakage control, we estimate that water losses can be reduced by an additional 20 percent globally by 2050. The resulting emissions reduction from pumped distribution could be .9 gigatons of carbon dioxide. Total installation cost is $137 billion and operating savings for utilities could be $903 billion by 2050. Implementing this simple solution could save 215 quadrillion gallons of water over thirty years.

#73 Green Roofs

Buildings and Cities

Green roofs use soil and vegetation as living insulation. Cool roofs reflect solar energy. Both reduce building energy use for heating and/or cooling.

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Green Roofs

Buildings and Cities

Rank and results by 2050 #73

Reduced CO2: 1 gigatons
Net cost (Billions US$): $1,393.29
Net operational savings: $988.46 billion
What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

NET COST (billions US $)

Net cost to implement

SAVINGS (billions US $)

Net savings by 2050

Impact:

In modeling green and cool roofs, we account for regional applications of each technology. If green roofs cover 30 percent of roof space by 2050 and cool roofs cover 60 percent, a total of 407 billion square feet of efficient roofing would be in place globally. Combined, these technologies could reduce carbon dioxide emissions by 0.8 gigatons at a cost of $1.4 trillion, thirty-year savings of $988 billion, and lifetime savings of $3 trillion.

#79 Net Zero Buildings

Buildings and Cities

A net zero building is one that has zero net energy consumption, producing as much energy, through onsite renewables, as it uses in a year.

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Net Zero Buildings

Buildings and Cities

Rank and results by 2050 #79

What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

NET COST (billions US $)

Net cost to implement

SAVINGS (billions US $)

Net savings by 2050

Impact:

There are no numbers on this page because net zero buildings are a mosaic of separate solutions. They draw on smart windows; green roofs; efficient heating, cooling, and water systems; better insulation; distributed energy and storage; and advanced automation. All are treated individually in our analysis. If net zero buildings are calculated as a single solution, assuming 9.7 percent of new buildings will be net zero by 2050, the integrated opportunity is 7.1 gigatons of carbon dioxide.

#80 Retrofitting

Buildings and Cities

Up to 80 percent of the energy buildings consume is wasted. Retrofitting them can address waste through efficient insulation, heating and cooling systems, and lighting.

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Retrofitting

Buildings and Cities

Rank and results by 2050 #80

What do these numbers mean?

TOTAL CO2-EQ REDUCTION (GT)

Total CO2-equivalent reduction in atmospheric greenhouse gases by 2050 (gigatons)

NET COST (billions US $)

Net cost to implement

SAVINGS (billions US $)

Net savings by 2050

Impact:

As with net zero buildings, there are no results presented from our models here. Building owners who retrofit existing residential and commercial building space install better insulation, improved heating and cooling equipment, upgraded management systems, etc. These solutions are accounted for individually. No retrofit will look exactly the same, making forecasting costs and savings nearly impossible.

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