Cut Emissions Industry, Materials & Waste Improve Materials

Deploy Alternative Insulation Materials

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Worker sprays insulation in building frame.

Deploy Alternative Insulation Materials is defined as using alternative building insulation materials in place of conventional ones. In particular, we highlight the impact of using cellulose instead of glass, mineral, or plastic insulation in new and retrofit buildings. Cellulose insulation manufacture and installation emits fewer GHGs to reach the same operational insulating performance than does manufacture and installation of conventional materials.

Last updated June 30, 2025

Solution Basics

(insulation units of 100 m2 and 1 m2·K/W)/yr

tCO2-eq/unit
1.59
units
Current 1.4×10⁷2.9×10⁷7.3×10⁷
Achievable (Low to High)

Climate Impact

GtCO2-eq/yr
Current 0.02 0.046 0.12
US$ per tCO2-eq
-121
Emergency Brake

CO₂, F-gas

Additional Benefits

183,187
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192

Overview

Thermal insulation materials are used in the walls, roofs, and floors of buildings to help maintain comfortable indoor temperatures. However, manufacture and installation of insulation materials produces GHG emissions. These are called embodied emissions because they occur before the insulation is used in buildings. Insulation embodied emissions offset a portion of the positive climate impacts from using insulation to reduce heating and cooling demand. A Canadian study found that over 25% of residential embodied emissions from manufacturing building materials can be due to insulation (Magwood et al., 2022). Using cellulose insulation made primarily from recycled paper avoids some embodied emissions associated with conventional insulation.

Insulation is manufactured in many different forms, including continuous blankets or boards, loose fill, and sprayed foam (Types of Insulation, n.d.). Most conventional insulation materials are nonrenewable inorganic materials such as stone wool and fiberglass. These require high temperatures (>1,300 °C) to melt the raw ingredients, consuming thermal energy and releasing CO₂ from fossil fuel combustion or grid power generation (Schiavoni et al., 2016). Other common insulations are plastics, including expanded polystyrene (EPS), extruded polystyrene (XPS), polyurethane (PUR), and polyisocyanurate (PIR). Producing these plastics requires the extraction of fossil fuels – primarily petroleum – for feedstocks, as well as high amounts of energy for processing (Harvey, 2007). 

F-gases are often used as blowing agents to manufacture rigid foam board insulation or install sprayed foam insulation (Figure 1). F-gases are GHGs with GWPs that can be hundreds or thousands of times higher than CO₂. High-GWP F-gases used in foam production are released into the atmosphere during all subsequent stages of the foam’s life cycle (Biswas et al., 2016; Waldman et al., 2023). The climate benefits of this solution during the installation stage are primarily due to avoiding these blowing agents. 

Alternative insulation is produced from plant or animal biomass (bio-based materials, see Figure 2) or waste products (recycled materials). Alternative insulation materials provide climate benefits by consuming less manufacturing energy, using renewable materials in place of fossil fuels, and eliminating high-GWP blowing agents (Sustainable Traditional Buildings Alliance, 2024). 

Figure 3 compares a variety of conventional and alternative insulation materials. While many bio-based and recycled materials could be used as alternatives to these conventional materials, this solution focuses on cellulose due to its effectiveness in avoiding emissions, low cost, and wide availability. Cellulose insulation is made primarily from recycled paper fibers, newsprint, and cardboard. These products are made into fibers and blended with fire retardants to produce loose or batt cellulose insulation (Figure 4) (Waldman et al., 2023; Wilson, 2021).

Figure 1. Properties and adoption of conventional and alternative insulation materials. Costs and emissions will vary from the values here depending on the insulation form (board, blanket, loose-fill, etc.).

Category Material High-GWP F-gases used? Median manufacturing and installation emissions* Mean product and installation cost** Estimated market share
(% by mass)
Conventional materials Stone wool No 0.31 623 20
Glass wool (fiberglass) No 0.29 508 34
EPS No 0.38 678 22
XPS Yes, sometimes 9.44 702 7
PUR/PIR Yes, sometimes 6.14 1,000 11
Alternative materials Cellulose No 0.05 441 2–13
Cork No 0.30 1,520 Commercially available, not widely used
Wood fiber No 0.13 814 Commercially available, not widely used
Plant fibers (kenaf, hemp, jute) No 0.18 467 Commercially available, not widely used
Sheep’s wool No 0.14 800 Commercially available, not widely used
Recycled PET plastic No 0.12 2,950 Commercially available, not widely used

*t CO₂‑eq (100-yr) to insulate 100m² to 1m²·K/W

**2023 US$ to insulate 100m² to 1m²·K/W. We use mean values for cost analysis to better capture the limited data and wide range of reported costs.

Although we are estimating the impact of using cellulose insulation in all buildings, the unique circumstances of each building are important when choosing the most appropriate insulation material. In this solution, we don’t distinguish between residential and commercial buildings, retrofit or new construction, different building codes, or different climates, but these would be important areas of future study.

In this solution, the effectiveness, cost, and adoption are calculated over a specified area (100 m2) and thermal resistance (1 m2·K/W). The chosen adoption unit ensures that all data are for materials with the same insulating performance. Due to limited material information, we assumed that insulation mass scales linearly with thermal resistance.

To better understand the adoption unit, a one-story residential building of 130 m2 floor area would require approximately 370 m2 of insulation area (RSMeans from The Gordian Group, 2023). For a cold climate like Helsinki, Finland, code requires insulation thermal resistance of 11 m2·K/W (The World Bank, n.d.). For a warm climate like Jerusalem, Israel, envelope thermal resistance requirements average 1.1 m2·K/W (The World Bank, n.d.). Therefore, depending on the location, anywhere from approximately 4–40 adoption units insulating 100 m2 to 1 m2·K/W may be needed to insulate a small single-story home to the appropriate area and insulation level.

Impact Calculator

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

Effectiveness

1.59
t CO2-eq/(insulation units of 100 m2 and 1 m2·K/)
25th
percentile
0.98
75th
percentile
1.81
1.59
median

Adoption

1.4×10⁷
(insulation units of 100 m2 and 1 m2·K/W)/yr
Low
2.9×10⁷
High
7.3×10⁷
1.4×10⁷
current
Achievable Range

Climate Impact

0.022
Gt CO2-eq/yr (100-yr)
06 Gt
0.038%
of total global emissions*
*59.09 Gt CO2-eq/yr (100-yr basis)

Maps

The effectiveness of deploying alternative insulation is not inherently dependent on geographic factors since it addresses emissions embodied in the manufacture and deployment of insulation materials. However, due to a lack of related data, we assumed a consistent global breakdown of currently used insulation materials when in reality, the exact mix of insulation currently used in different geographic locations will affect the emissions impact of switching to alternative materials.

Building insulation is used in higher quantities in cold or hot climates, so deploying alternative insulation is more likely to be relevant and adopted in such climates. Other geographic factors also impact adoption: Areas with higher rates of new construction will be better able to design for cellulose or other alternative insulation materials, and drier climates will face a lower risk of mold growth on these materials. Local building codes, including fire codes, can also affect the adoption of alternative materials.

There are no maps for the Alternative Insulation solution. It is intended to address emissions embodied in the manufacture and deployment of insulation materials and has no intrinsic dependence on geographic factors.

The Details

Current State

To insulate 100 m2 to a thermal resistance of 1 m2·K/W using entirely cellulose insulation in place of the current baseline mix of insulation materials is expected to avoid 1.59 t CO₂‑eq on a 100-yr basis (Table 1). Effectiveness for this solution measures the one-time reduced emissions from manufacturing and installing insulation. Insulation also reduces the energy used while a building is operating, but those emissions are addressed separately in the Improve Building Envelopes solution. 

Conventional insulation cost was considered to be a weighted average cost of the current baseline insulation mix, including a small amount of cellulose insulation currently in use.

The largest contributor to conventional insulation embodied emissions is using high-GWP blowing agents to manufacture or install XPS, PUR, or PIR foam. We assumed the use of F-gas blowing agents for all foams, although these are already being regulated out of use globally (Amendment to the Montreal Protocol on Substances That Deplete the Ozone Layer, 2016) and an unknown amount of low-GWP blowing agents are currently use (such as hydrocarbons or CO₂ ). Therefore, we anticipate the effectiveness of this solution will decrease as F-gases are used less in the future. We assumed that 100% of blowing agents are emitted over the product lifetime.

Cellulose has the greatest avoided emissions of all of the alternative materials we evaluated (Figure 1). The next most effective materials were recycled PET, wood fibers, and sheep’s wool. Conventional materials like XPS, PUR, and PIR that are foamed with F-gases had the highest GHG emissions. For bio-based materials, we did not consider biogenic carbon as a source of carbon sequestration due to quantification and permanence concerns. 

Table 1. Effectiveness at reducing emissions.

Unit: t CO₂‑eq /insulation required to insulate 100 m2 to a thermal resistance of 1 m2·K/W, 100-yr basis

25th percentile 0.98
mean 1.34
median (50th percentile) 1.59
75th percentile 1.81

Available cost data are variable for all materials, particularly those in early-stage commercialization. The mean cost of purchasing and installing cellulose insulation is less than that of any other conventional or alternative insulation material (Figure 1). Compared with the average cost of conventional insulation, the mean cost savings for cellulose insulation is US$193/100 m2 insulated to a thermal resistance of 1 m2·K/W. Since most buildings are insulated over greater areas to higher thermal resistances, these savings would quickly add up. When considering the mean cost per median climate impact, cellulose insulation saves US$121/t CO₂‑eq (100-yr basis), making it an economically and environmentally beneficial alternative (Table 2).

We considered conventional insulation cost to be a weighted average cost of the current baseline insulation mix, including a small amount of cellulose insulation currently in use.

For conventional insulation, material costs of purchasing the insulation are higher than costs for installation (US$540 and US$97, respectively, to insulate 100 m2 to a thermal resistance of 1 m2·K/W). Cellulose has a lower product cost and comparable installation costs to conventional materials. We considered all costs to be up-front and not spread over the lifetime of the material or building. For each material type, cost will vary based on the form of the insulation (board, loose, etc.) and this should be accounted for when comparing insulation options for a particular building. 

We determined net costs of insulation materials by adding the mean cost to purchase the product and the best estimation of installation costs based on available information. Installation costs were challenging to find data on and therefore represent broad assumptions of installation type and labor. Cost savings were determined by subtracting the weighted average net cost of conventional materials to the net cost of an alternative material. Although we used median values for other sections of this assessment, the spread of data was large for product cost estimates and the mean value was more appropriate in the expert judgment of our reviewers. 

Table 2. Cost per unit of climate impact.

Unit: 2023 US$/t CO₂‑eq, 100-yr basis

estimate -121

Little information is available about the learning rate for new insulation materials. Mályusz and Pém (2013) evaluated how labor time decreased with repetitive cycles for installing roof insulation. They found a learning rate of ~90%, but only for this specific insulation scenario, location, and material. Additionally, this study does not include any product or manufacturing costs that may decrease with scale.

In general, labor time for construction projects decreases with repetitive installation, including improved equipment and techniques and increased construction crew familiarity with the process (SaravanaPrabhu & Vidjeapriya, 2021). However, Malhotra and Schmidt (2020) classify building envelope retrofits as technologies that are highly customized based on user requirements, regulations, physical conditions, and building designs, likely leading to learning rates that are slow globally but where local expertise could reduce installation costs.

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 gradual, emergency brake, or delayed.

Deploy Alternative Insulation Materials is an EMERGENCY BRAKE climate solution. It has the potential to deliver a more rapid impact than nominal and delayed solutions. Because emergency brake solutions can deliver their climate benefits quickly, they can help accelerate our efforts to address dangerous levels of climate change. For this reason, they are a high priority.

Adoption

Adoption data are extremely limited for alternative insulation materials. All adoption data and estimates are assumed to apply to both residential and commercial buildings, although in reality the uptake of alternative insulation materials will vary by building type due to differences in structures, climate, use type, and regulations. We assume that future uptake of alternative insulation is used only during retrofit or new construction, or when existing insulation is at the end of its functional lifetime.

European sources report that 2–13% of the insulation market is alternative materials. Depending on the source, this could include renewable materials, bio-based insulation, or recycled materials. In 2018 in the United States, 5% of total insulation area in new single-family homes was insulated with cellulose (Insulation Choices Revealed in New Study, 2019).

To convert estimated cellulose adoption percentage into annual insulation use, we estimated 26 Mt of all installed global insulation materials in 2023 based on a report from The Freedonia Group (2024). We calculated an annual use of approximately 1.7 billion insulation units of 100 m2 at a thermal resistance of 1 m2·K/W. Therefore, the median cellulose adoption is 140 million units/yr at 100 m2 at 1 m2·K/W, calculated from the median of the 2–13% adoption range. 

Since this calculation is based on more alternative materials than just cellulose and is heavily reliant on European data where we assume adoption is higher, this estimate of current adoption (Table 3) is most likely an overestimate.

The little adoption data that were considered in this section are mostly for Europe, and some for the United States. We recognize this limited geographic scope creates bias, and hope this work inspires research and data sharing on this topic in underrepresented regions.

Table 3. Current (2017–2022) adoption level.

Unit: units of insulation/yr installed to insulate 100 m2 to a thermal resistance of 1 m2·K/W

25th percentile 9000000
mean 130000000
median (50th percentile) 140000000
75th percentile 170000000

Very few data are available that quantify adoption trends. In a regional study of several bio-based insulation materials, Rabbat et al. (2022) estimated French market annual growth rates of 4–10%, with cellulose estimated at 10%. Petcu et al. (2023) estimated the European adoption of recycled plastic and textile insulation, biomass fiber insulation, and waste-based insulation to have increased from 6% to 10% between 2012 and 2020.

When accounting for the calculated current adoption, these growth rates mean a median estimated annual increase of 500,000 insulation units/yr required to insulate 100 m2 to a thermal resistance of 1 m2·K/W. The increasing adoption of biobased insulation decreases the use of conventional insulation materials in those regions.

This adoption trend (Table 4) is likely an overestimate, as it is biased by high European market numbers and based on the likely high estimate we made for current adoption. 

Table 4. 2012–2020 adoption trend.

Unit: annual change in units of insulation/yr installed to insulate 100 m2 to a thermal resistance of 1 m2·K/W

25th percentile 500000
mean 800000
median (50th percentile) 500000
75th percentile 1300000

No estimates have been found for the adoption ceiling of this solution, although we expect it to be high given low rates of current adoption and projected increases in building construction in the coming decades [International Energy Agency (IEA), International Renewable Energy Agency, & United Nations Climate Change High-Level Champions, 2023]. Two physical factors that could influence adoption are availability of alternative materials and thickness of insulation.

For cellulose insulation, availability does not seem to limit adoption. The Food and Agriculture Organization of the United Nations (2023) reports that there is a much higher annual production of cellulose-based materials (>300 Mt annually of cartonboard, newsprint, and recycled paper) than the overall demand for insulation globally (>25 Mt annual demand; Global Insulation Report, 2024). However, other uses for cellulose products may create competition for this supply.

Increased thickness of insulation could also be a limiting factor since this would reduce adoption by decreasing building square footage, in particular making retrofits more challenging and expensive. Deer et al. (2007) reported that the average cellulose thermal resistance is similar to mineral and glass wool, and lower than plastic insulations made of polystyrene and other foams. If we assume that 50% of plastic insulation cannot be replaced with cellulose due to thickness limitations, this would represent ~20% of current insulation that could not be replaced without structural changes to the building. Therefore, we calculate the adoption ceiling to be 80% of the current insulation that would be reasonably replaceable or 140 million units/yr required to insulate 100 m2 to a thermal resistance of 1 m2·K/W (Table 5).

Uptake of celllose insulation could also be limited by its susceptibility to absorbing moisture, limiting its use in wet climates or structures that retain moisture, such as flat roofs. Commercialization of alternative insulation materials beyond cellulose and in many different forms (e.g., board, loose-fill) will increase the adoption ceiling across more building types.

Table 5. Adoption ceiling.

Unit: units of insulation installed to insulate 100 m2 to a thermal resistance of 1 m2·K/W/yr.

25th percentile N/A
mean N/A
median (50th percentile) 140000000 (estimate)
75th percentile N/A

No estimates have been found for feasible global adoption of this solution. Rabbat et al. (2022) estimated the adoption levels of several bio-based insulation materials in France in 2050. For cellulose wadding, this was estimated to be 2.1 times the commercialized volume in France in 2020. Although we do not expect France to be representative of the rest of the world, if the predicted adoption trend holds across the world then we expect low adoption in 2050 to be 2.1 times greater than 2023 adoption. This is 29 million units/yr to insulate 100 m2 to a thermal resistance of 1 m2·K/W (Table 6).

The IEA (2023) claims that building envelopes need to have their retrofit rate increase by 2.5 times over the current rate in order to meet net zero targets (2023). This is a reasonable high-adoption scenario. Assuming that more retrofits of buildings occur and greater amounts of alternative insulation are installed in new buildings, we estimate that high future adoption of new insulation could occur at 2.5 times the rate of the low-adoption scenario. This is 73 million units/yr to insulate 100 m2 to a thermal resistance of 1 m2·K/W (Table 6).

Adoption will be facilitated or limited by local regulations around the world. Building codes will determine the location and extent of use of cellulose or other bio-based insulation. We expect uptake to be different between residential and commercial buildings, but due to insufficient data, we have grouped them in our adoption estimates.

Table 6. Range of achievable adoption levels.

Unit: units of insulation installed to insulate 100 m2 to a thermal resistance of 1 m2·K/W/yr

Current Adoption 14000000
Achievable – Low 29000000
Achievable – High 73000000
Adoption Ceiling 140000000

Impacts

The climate impacts for this solution are modest compared to current global GHG emissions. Not all conventional insulations have a high environmental impact due to the use of a wide range of materials, forms, and installation methods as well as the recent adoption of lower-GWP blowing agents. Therefore, the potential for further emissions savings is limited.

We quantified the effectiveness and adoption of cellulose insulation, which has the lowest emissions and, therefore, the highest climate impacts of the insulation materials we evaluated. With high adoption, 1.2 Gt CO₂‑eq on a 100-yr basis could be avoided over the next decade (Table 7).

While we only considered the adoption of cellulose insulation in this analysis, a realistic future for lowering the climate impact of insulation may include other bio-based materials, too. Utilizing a greater range of materials should increase adoption and climate impact due to more available forms, sources, and thermal resistance values of bio-based insulation.

Note that the current climate impact is calculated using a current materials baseline that includes a small fraction of cellulose. This means that the reported current adoption impact is a slight underestimate compared with the impacts for replacing entirely conventional insulation with the current amount of cellulose insulation in use.

Table 7. Climate impact at different levels of adoption.

Unit: Gt CO₂‑eq/yr, 100-yr basis

Current Adoption 0.022
Achievable – High 0.046
Achievable – Low 0.12
Achievable Ceiling 0.22

Income and work

Some alternative insulations can be cheaper than conventional materials. Although there is large variation in evaluation methods and reported costs, our analysis found that cellulose and plant fibers are cheaper than conventional insulation materials such as stone wool, glass wool, and EPS (Figure 1). Depending on the applicable climate conditions and insulation form, switching to alternative insulation materials can result in cost savings for consumers, including homeowners and business owners.

Health

Conventional insulation materials may contribute to poor indoor air quality, especially during installation, and contribute to eye, skin, and lung irritation (Naldzhiev et al., 2020; Stamm et al., 2022; Wi et al., 2021). Additionally, off-gassing of flame retardants and other volatile organic compounds and by-products of conventional insulation can occur shortly after installation (Naldzhiev et al., 2020). Using bio-based alternative insulation products can minimize the health risks during and after installation (McGrath et al., 2023).

Water Resources

Although there is not a scientifically consistent approach to compare the environmental impacts of conventional and alternative insulation materials, a review analysis of 47 studies on insulation concluded that bio-based insulation materials generally have lower impacts as measured through acidification, eutrophication, and photochemical ozone creation potentials compared than do conventional materials (Füchsl et al., 2022). Other alternative materials such as wood fiber and miscanthus also tend to have a lower environmental footprint (Schulte et al., 2021). The water demand for wood and cellulose is significantly lower than that for EPS (about 2.8 and 20.8 l/kg respectively compared with 192.7 l/kg for EPS) (Zabalza Bribián et al., 2011). While the limited evidence suggests that the alternative material tends to be better environmentally, there is an urgent need to conduct life cycle assessments using a consistent approach to estimate the impact of these materials.

Other

Manufacturing and installation emissions reductions due to the use of alternative building thermal insulation materials are both permanent and additional. 

Permanence: There is a low risk of the emissions reductions for this solution being reversed. By using cellulose insulation instead of inorganic or plastic-based insulation, a portion of the manufacturing and installation emissions are never generated in the first place, making this a permanent reduction. Emissions from high-temperature manufacturing, petroleum extraction, and blowing agent use are all reduced through this approach.

Additionality: The GHG emissions reductions from alternative insulation materials are additional because they are calculated here relative to a baseline insulation case. This includes a small amount of cellulose materials included in baseline building insulation. Therefore, avoided emissions represent an improvement of the current emissions baseline that would have occurred in the absence of this solution. 

Cellulose insulation is susceptible to water absorption, which can lead to mold growth in wet or humid environments (Andersen & Rasmussen, 2025; Petcu et al., 2023). Mitigating this risk either requires an antifungal treatment for the material or limits adoption to particular climates. The thermal performance of cellulose insulation can decrease over time due to water absorption, settling, or temperature changes, but installing it as dense-packed or damp-spray can mitigate this (Wang & Wang, 2023; Wilson, 2021).

Bio-based insulation materials tend to be combustible, meaning they contribute more to the spread of a fire than non-combustible stone or glass insulation. Some bio-based materials are classified as having minimal contribution to a fire, such as some cellulose forms, rice husk, and flax (Kumar et al., 2020). These materials are less likely to contribute to a fire than very combustible plastic insulation such as EPS, XPS, and PUR. Fire codes – as well as other building and energy codes – could limit adoption, risking a lack of solution uptake due to regulatory setbacks (Northeast Bio-Based Materials Collective 2023 Summit Proceedings, 2023). 

Additives such as fire retardants and anti-fungal agents are added to bio-based insulation along with synthetic binders, which can lead to indoor air pollution from organic compounds, although likely in low concentrations (Maskell et al., 2015; Rabbat et al., 2022).

Bio-based insulation materials including cellulose often have lower thermal resistance than some conventional insulation materials. In particular, bio-based materials may require a thicker layer than plastic insulation to reach the same insulating performance (Esau et al., 2021; Rabbat et al., 2022). Usable floor area within a building would need to be sacrificed to accommodate thicker insulation, which would potentially depreciate the structure or impact the aesthetic value (Jelle, 2011). This would be a more significant trade-off for retrofit construction and buildings in densely developed urban areas.

Sourcing bio-based materials has environmental trade-offs that come from cultivating biomass, such as increased land use, fertilizer production, and pesticide application (Schulte et al., 2021). Using waste or recycled materials could minimize these impacts. Binders and flame-retardants may also be required in the final product, leading to more processing and material use (Sustainable Traditional Buildings Alliance, 2024).

Reinforcing

Upgrading insulation to lower-cost and lower-emitting alternative materials should increase the adoption of other building envelope solutions as they can be installed simultaneously to optimize cost and performance. 

Increasing the manufacturing of cellulose insulation, which contains large amounts of recycled paper, could increase the revenues for paper recycling.

Competing

The use of biomass as raw material for insulation will reduce the availability and increase the cost of using it for other applications. For cellulose, global production of cellulose materials (>300 Mt annually of cartonboard, newsprint, and recycled paper (Forestry Production and Trade, 2023)) is an order of magnitude higher than the demand for insulation materials (>25 Mt annual demand (The Freedonia Group, 2024)), so the overall impact should be small.

Reducing the demand for conventional insulation products and instead making insulation that produces fewer GHGs during manufacturing would slightly reduce the global climate impact of other industrial manufacturing solutions. This is because less energy overall would be used for manufacturing, and therefore other technologies for emissions reductions would be less impactful for insulation production.

Consensus of effectiveness in reducing building sector emissions: Mixed

There is scientific consensus that using building insulation with lower embodied emissions will reduce GHG emissions, but expert opinions about the magnitude of possible emissions reductions as well as the accuracy of determining these reductions are mixed. 

Biswas et al. (2016) determined that, for insulation, avoided emissions from reduced heating and cooling energy tend to outweigh the embodied emissions. However, others emphasize that as buildings become more energy-efficient, material embodied emissions become a larger factor in their carbon footprint (Cabeza et al., 2021; Grazieschi et al., 2021). Embodied emissions from insulation can be substantial: Esau et al. (2021) analyzed a mixed-use multifamily building and found that selecting low-embodied-carbon insulation could reduce building embodied emissions by 16% at no cost premium.

Multiple studies have found that some sustainable insulation materials have lower manufacturing emissions than traditional insulation materials (Asdrubali et al., 2015; Füchsl et al., 2022; Kumar et al., 2020; Schiavoni et al., 2016). However, researchers have highlighted the difficulty in evaluating environmental performance of different insulation materials (Cabeza et al., 2021; Grazieschi et al., 2021). Gelowitz and McArthur (2017) found that construction product Environmental Product Declarations contain many errors and discrepancies due to self-contradictory or missing data. Füschl et al. (2022) conducted a meta-analysis and cautioned that “it does not appear that a definitive ranking [of insulation materials] can be drawn from the literature.” In our analysis, we attempt to compare climate impact between materials but acknowledge that this can come from flawed and inconsistent data.

Despite the difficulties in comparing materials, there is high consensus that cellulose is a strong low-emissions insulation option due to its low embodied carbon, high recycled content, and good thermal insulating performance (Wilson, 2021).

The results presented in this document summarize findings from four reviews and meta-analyses, 14 original studies, three reports, 27 Environmental Product Declarations, and two commercial websites reflecting current evidence from eight countries as well as data representing global, North American, or European insulation materials. We recognize this limited geographic scope creates bias, and hope this work inspires research and data sharing on this topic in underrepresented regions.

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!

Nonprofit Leaders

  • Advocate for financial incentives, improved building and fire codes, and educational programs for alternative insulation.
  • Conduct research to improve alternative insulation materials’ manufacturing, adoption, supply chain access, and circularity.
  • Offer educational resources, one-stop shops for retrofitting and weatherization, installation demonstrations, and tours of model builds for commercial and private developers, highlighting the cost savings and environmental benefits of alternative insulation.
  • Create, join, or administer green building certification schemes and/or public-private partnerships that offer information, training, and general support for alternative insulation.

Further information:

Philanthropists and International Aid Agencies

  • Finance only new construction and retrofits that utilize alternative insulation and other low-carbon practices.
  • Offer grants for developers utilizing alternative insulation and other climate-friendly practices.
  • Create financing programs for private construction in low-income or under-resourced communities.
  • Create new contractual terms that require embodied emissions data from materials and methods.
  • Advocate for financial incentives, improved building and fire codes, and educational programs for alternative insulation.
  • Fund research to improve alternative insulation materials’ manufacturing, adoption, supply chain access, and circularity.
  • Offer educational resources, one-stop shops for retrofitting and weatherization, installation demonstrations, and tours of model builds for commercial and private developers, highlighting the cost savings and environmental benefits of alternative insulation.
  • Create or join green building certification schemes and/or public-private partnerships that offer information, training, and general support for alternative insulation.

Further information:

Technologists and Researchers

  • Develop and improve existing alternative insulation materials or innovate new materials with enhanced insulation performance.
  • Investigate ways to increase the durability of alternative insulation, such as resistance to moisture, pests, and fire.
  • Find uses for recycled materials in alternative insulation and ways to improve the circular economy.
  • Innovate new manufacturing methods that reduce electricity use and emissions.
  • Design new application systems for alternative insulation that can be done without much additional training or licensing/certification.
  • Create new methods of disposal for conventional insulation during demolitions.
  • Research adoption rates of alternative insulation materials across regions and environments.

Further information:

Communities, Households, and Individuals

  • Finance or develop only new construction and retrofits that utilize alternative insulation and other low-carbon practices.
  • Take advantage of financial incentives such as subsidies, tax credits, and grants for installing alternative insulation.
  • Whenever possible, install insulation that does not use F-gas blowing agents.
  • Advocate for financial incentives, improved building and fire codes, and educational programs for alternative insulation.
  • Conduct local research to improve alternative insulation materials’ manufacturing, adoption, supply chain access, and circularity.
  • Organize local “green home tours” and open houses to showcase climate-friendly builds and foster demand by highlighting cost savings and environmental benefits of alternative insulation.
  • Create or join green building certification schemes, green building councils, and/or public-private partnerships that offer information, training, and general support for alternative insulation.
  • Capture community feedback and share it with local policymakers to address barriers such as permitting logistics or upfront costs, helping to share policies that drive adoption.

Further information:

“Take Action” Sources

References

Adams, M., Burrows, V., & Richardson, S. (2019). Bringing embodied carbon upfront: Coordinated action for the building and construction sector to tackle embodied carbon. World Green Building Council, Advancing Net Zero, Ramboll, & C40 Cities. https://worldgbc.s3.eu-west-2.amazonaws.com/wp-content/uploads/2022/09/22123951/WorldGBC_Bringing_Embodied_Carbon_Upfront.pdf

Amendment to the Montreal Protocol on Substances that Deplete the Ozone Layer. (2016, October 15). https://treaties.un.org/doc/Treaties/2016/10/20161015%2003-23%20PM/Ch_XXVII-2.f-English%20and%20French.pdf

Andersen, B., & Rasmussen, T. V. (2025). Biobased building materials: Moisture characteristics and fungal susceptibility. Building and Environment, 112720. https://doi.org/10.1016/j.buildenv.2025.112720

Asdrubali, F., D’Alessandro, F., & Schiavoni, S. (2015). A review of unconventional sustainable building insulation materials. Sustainable Materials and Technologies, 4, 1–17. https://doi.org/10.1016/j.susmat.2015.05.002

Biswas, K., Shrestha, S. S., Bhandari, M. S., & Desjarlais, A. O. (2016). Insulation materials for commercial buildings in North America: An assessment of lifetime energy and environmental impacts. Energy and Buildings, 112, 256–269. https://doi.org/10.1016/j.enbuild.2015.12.013

Cabeza, L. F., Boquera, L., Chàfer, M., & Vérez, D. (2021). Embodied energy and embodied carbon of structural building materials: Worldwide progress and barriers through literature map analysis. Energy and Buildings, 231, 110612. https://doi.org/10.1016/j.enbuild.2020.110612

Carbon Removals Expert Group Technical Assistance. (2023, December). Review of certification methodologies for long-term biogenic carbon storage in buildings. European Commission. https://climate.ec.europa.eu/system/files/2023-12/policy_carbon_expert_biogenic_carbon_storage_in_buildings_en.pdf

Deer, C., George, M., Kaluza, P., Loudon, Moore, G., Musick, M., Musick, R., Seifert, R., & Woodward, J. (2007). Alaska Residential Building Manual. Alaska Housing Finance Corporation. https://www.ahfc.us/application/files/2813/5716/1325/building_manual.pdf

Esau, R., Jungclaus, M., Olgyay, V., & Rempher, A. (2021). Reducing Embodied Carbon in Buildings: Low-Cost, High-Value Opportunities. RMI. http://www.rmi.org/insight/reducing-embodied-carbon-in-buildings

Fabbri, M., Rapf, O., Kockat, J., Fernández Álvarez, X., Jankovic, I., & Sibileau, H. (2022). Putting a stop to energy waste: How building insulation can reduce fossil fuel imports and boost EU energy security. Buildings Performance Institute Europe. https://www.bpie.eu/wp-content/uploads/2022/05/Putting-a-stop-to-energy-waste_Final.pdf

Forestry Production and Trade. (2023). [Dataset]. FAOSTAT. https://www.fao.org/faostat/en/#data/FO

Füchsl, S., Rheude, F., & Röder, H. (2022). Life cycle assessment (LCA) of thermal insulation materials: A critical review. Cleaner Materials, 5, 100119. https://doi.org/10.1016/j.clema.2022.100119

Gelowitz, M. D. C., & McArthur, J. J. (2017). Comparison of type III environmental product declarations for construction products: Material sourcing and harmonization evaluation. Journal of Cleaner Production, 157, 125–133. https://doi.org/10.1016/j.jclepro.2017.04.133

Global Alliance for Buildings and Construction, International Energy Agency, and the United Nations Environment Programme. (2020). GlobalABC Roadmap for Buildings and Construction: Towards a zero-emission, efficient and resilient buildings and construction sector. International Energy Agency. https://www.iea.org/reports/globalabc-roadmap-for-buildings-and-construction-2020-2050

Grazieschi, G., Asdrubali, F., & Thomas, G. (2021). Embodied energy and carbon of building insulating materials: A critical review. Cleaner Environmental Systems, 2, 100032. https://doi.org/10.1016/j.cesys.2021.100032

Harvey, L. D. D. (2007). Net climatic impact of solid foam insulation produced with halocarbon and non-halocarbon blowing agents. Building and Environment, 42(8), 2860–2879. https://doi.org/10.1016/j.buildenv.2006.10.028

Installed Cost of Residential Siding Comparative Study. (2023). RSMeans / The Gordian Group. https://www.gobrick.com/content/userfiles/files/RSMeans%20Residential%20Siding%20Comparative%20Cost%20Wall%20System%20Study%20Final%202023-09-15.pdf

Insulation Choices Revealed in New Study. (2019, June 19). Home Innovation Research Labs. https://www.homeinnovation.com/trends_and_reports/trends/insulation_choices_revealed_in_new_study

International Energy Agency. (2023). Building envelopes. https://www.iea.org/energy-system/buildings/building-envelopes

International Energy Agency, International Renewable Energy Agency, & United Nations Climate Change High-Level Champions. (2023). Breakthrough agenda report 2023. https://www.iea.org/reports/breakthrough-agenda-report-2023

Jelle, B. P. (2011). Traditional, state-of-the-art and future thermal building insulation materials and solutions – Properties, requirements and possibilities. Energy and Buildings, 43(10), 2549–2563. https://doi.org/10.1016/j.enbuild.2011.05.015

Kumar, D., Alam, M., Zou, P. X. W., Sanjayan, J. G., & Memon, R. A. (2020). Comparative analysis of building insulation material properties and performance. Renewable and Sustainable Energy Reviews, 131, 110038. https://doi.org/10.1016/j.rser.2020.110038

Magwood, C., Bowden, E., & Trottier, M. (2022). Emissions of Materials Benchmark Assessment for Residential Construction Report. Passive Buildings Canada and Builders for Climate Action.

Malhotra, A., & Schmidt, T. S. (2020). Accelerating Low-Carbon Innovation. Joule, 4(11), 2259–2267. https://doi.org/10.1016/j.joule.2020.09.004

Mályusz, L., & Pém, A. (2013). Prediction of the learning curve in roof insulation. Automation in Construction, 36, 191–195. https://doi.org/10.1016/j.autcon.2013.04.004

Mapping energy efficiency: A global dataset on building code effectiveness and compliance: Country profiles. (n.d.). [Dataset]. The World Bank. https://www.worldbank.org/content/dam/sites/buildinggreen/doc/building_green_country_profile.pdf

Maskell, D., Da Silva, C., Mower, K., Rana, C., Dengel, A., Ball, R., Ansell, M., Walker, P., & Shea, A. (2015, June 22). Properties of bio-based insulation materials and their potential impact on indoor air quality. First International Conference on Bio-based Building Materials, Clermont-Ferrand, France.

McGrath, T., Seigel, K., & Dickinson, M. (2023). Embodied Carbon and Material Health in Insulation. Healthy Building Network, Perkins&Will. https://habitablefuture.org/wp-content/uploads/2024/03/96-Carbon-Health-Insulation.pdf

Naldzhiev, D., Mumovic, D., & Strlic, M. (2020). Polyurethane insulation and household products – A systematic review of their impact on indoor environmental quality. Building and Environment, 169, 106559. https://doi.org/10.1016/j.buildenv.2019.106559

Northeast Bio-based Materials Collective 2023 summit proceedings. (2023). https://massdesigngroup.org/sites/default/files/file/2024/Northeast%20Bio-Based%20Materials%20Collective%202023%20Summit%20Proceedings.pdf

Petcu, C., Hegyi, A., Stoian, V., Dragomir, C. S., Ciobanu, A. A., Lăzărescu, A.-V., & Florean, C. (2023). Research on Thermal Insulation Performance and Impact on Indoor Air Quality of Cellulose-Based Thermal Insulation Materials. Materials, 16(15), Article 15. https://doi.org/10.3390/ma16155458

Rabbat, C., Awad, S., Villot, A., Rollet, D., & Andrès, Y. (2022). Sustainability of biomass-based insulation materials in buildings: Current status in France, end-of-life projections and energy recovery potentials. Renewable and Sustainable Energy Reviews, 156, 111962. https://doi.org/10.1016/j.rser.2021.111962

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RSMeans from The Gordian Group. (2023). Installed Cost of Residential Siding Comparative Study. https://www.gobrick.com/content/userfiles/files/RSMeans%20Residential%20Siding%20Comparative%20Cost%20Wall%20System%20Study%20Final%202023-09-15.pdf

SaravanaPrabhu, G., & Vidjeapriya, R. (2021). Comparative Analysis of Learning Curve Models on Construction Productivity of Diaphragm Wall and Pile. IOP Conference Series: Materials Science and Engineering, 1197(1), 012004. https://doi.org/10.1088/1757-899X/1197/1/012004

Schiavoni, S., D׳Alessandro, F., Bianchi, F., & Asdrubali, F. (2016). Insulation materials for the building sector: A review and comparative analysis. Renewable and Sustainable Energy Reviews, 62, 988–1011. https://doi.org/10.1016/j.rser.2016.05.045

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Credits

Lead Fellow

  • Sarah Gleeson

Contributors

  • Ruthie Burrows

  • James Gerber

  • Yusuf Jameel 

  • Daniel Jasper

  • Alex Sweeney

Internal Reviewers

  • Aiyana Bodi

  • Hannah Henkin

  • Ted Otte

  • Amanda Smith

  • Tina Swanson

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.

  • 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.

  • Benefits of climate solutions that extend beyond their ability to reduce emissions or store carbon (e.g., benefits to public health, water quality, biodiversity, advancing human rights).

  • 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.

  • 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.

  • 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.

  • 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

  • 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.

  • 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.

  • 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 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.

  • 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.

  • 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.

  • 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.

  • internal rate of return

  • A measure of energy

  • 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.

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

  • 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.

  • megaton or million metric tons

  • 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.

  • 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.

  • 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.

  • 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.

  • 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. 

  • 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.

  • 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

  • The rate at which a climate solution physically affects the atmosphere after being deployed. At Project Drawdown, we use three categories: emergency brake (fastest impact), gradual, or delayed (slowest impact).

  • 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.

  • 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 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.

  • 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

  • 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 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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