Worker installing cavity insulation between interior and exterior brick walls.
Technical Summary


Project Drawdown defines insulation as the use of high levels of improved materials in building envelopes that resist heat flow and regulate indoor temperatures. This solution replaces the conventional practice of using less thermal resistance in residential and commercial buildings.

Insulating the wall and roof surface area of buildings is one of the most accessible and effective ways to reduce heating and cooling energy use—and, therefore, greenhouse gas emissions—in the built environment. Increasing insulation of older buildings through retrofit and increasing the average R-value of new building stock costs more than current normal practices, but has a significant return on investment from lower operating costs due to reductions in heating and cooling costs. All materials are not the same however since some require manufacture processes that generate much emissions, these are called embodied emissions of insulation. There are many low carbon bio-based materials like waste paper and hemp that can lower these embodied emissions significantly, but they may not be applicable in all cases.


To determine the emissions reduction potential of global adoption of high quality insulation in climate appropriate regions, the global stock of buildings was first analyzed to determine a total addressable market of building surface area appropriate for insulation. We separated the heating-dominated from the cooling-dominated areas and estimated possible heat loss or heat gain due to buildings of today’s average u-values in different climate zones according to heating-degree days and cooling-degree days. The energy loss (gain) is used to estimate the energy demand for heating (cooling) which was used to benchmark again global estimates for final space heating (cooling) energy. Then we adjusted the u-values to align with Passive House standards for heating dominated climates (and slightly less ambitious for cooling-dominated) and estimated the thermal energy saved. This was converted to emissions according to global average heating and cooling energy emissions factors.

We additionally estimated the typical shares of materials used for insulation and estimated the embodied emissions of each but with an assumption that low-carbon materials like waste paper (cellulose) and hemp increase from an estimated 6 percent of total to 30 percent.

Total Addressable Market

The total addressable market for insulation is based on estimated supply for commercial and residential building space in million square meters from 2020 to 2050, derived from the International Energy Agency’s (IEA’s) data.

With very limited data, we have assumed that current adoption[1] of insulation corresponds to around 30 percent globally.

Adoption Scenarios

Impacts of increased adoption of insulation from 2020 to 2050 were generated based on two growth scenarios. These were assessed in comparison with a Reference Scenario, in which the solution’s market share was fixed at the current levels.

  • Scenario 1: For this scenario, an insulation retrofit rate of 1.6 percent was applied.
  • Scenario 2: For this scenario, an insulation retrofit rate of 2 percent was applied.

Emissions Model

Emissions assumptions were based on a combination of emissions factors related to heating fuel and grid electricity factors for cooling energy using global average heating and cooling demands, and the emissions factors from the Intergovernmental Panel on Climate Change (IPCC). Additionally the embodied emissions from typical insulation materials were collected from industry sources.

Financial Model

Financial variables were collected and assessed for the costs of a variety of common insulation materials, including cellulose, polyurethane, stone and glass wools. Estimated thickness of each material to obtain the required u-value were estimated and used to price the per square-meter insulation need of each material before weighting by market demand. Over time the market shares would shift as more low carbon materials are used, and this was taken into account. The average first cost per square meter of insulated surface was estimated as US$4.00 more than typical levels of insulation.[2] Operational savings were derived by multiplying the reduced heating and cooling use by the average costs for the type of heating or cooling that would have been delivered.


The insulation solution was integrated with others in the Buildings Sector by first prioritizing all solutions according to the point of impact on building energy usage. This meant that building envelope solutions like insulation were first, building systems like building automation systems were second, and building applications like heat pumps were last.[3] The impact on building energy demand was calculated for highest priority solutions, and then lower priority solutions were adjusted accordingly. For integrating Project Drawdown solutions in the Building Sector, insulation was the first solution to be considered because of the low cost, likely adoption, and significant mitigation impact of bolstering the building envelope. All other building envelope and building solutions impacting heating and cooling use are impacted by insulation at the point of integration.

Additionally, as this model’s result is partly dependent on the supply of biogenic low carbon materials like hemp, and waste materials like waste paper, Project Drawdown’s integrated biomass and integrated waste models included allocations for Insulation to ensure that no double counting or unrealistic projections occurred.


Scenario 1 results show a mitigation impact of 17 gigatons of carbon dioxide-equivalent emissions over the period 2020–2050 and US$21 trillion in energy savings. This scenarios estimates an additional US$751 billion in insulation cost. The increased adoption of insulation in Scenario 2 results in a mitigation impact of 19 gigatons of emissions for a cost of US$831 billion.  It does, however, save an estimated US$24 trillion in heating and cooling costs.


There is little peer-reviewed literature assessing the potential global increased adoption of insulation, so the results developed require a significant number of assumptions and reasoned extrapolations of the data that does exist. Temperature variation and human comfort levels in buildings can significantly affect the adoption of insulation. Because of rising outside temperatures, Anthropogenic global warming is expected to decrease average energy used for heating buildings worldwide, but is also expected to drive more electricity use for cooling. These effects were not considered for the model prognostications.

The impact of the low-carbon materials is noticeable. This contributed to a higher emission impact than would have been estimated. The building industry is coming to the realization that unless embodied emissions are taken into account when retrofitting or designing new buildings, significant emissions may be generated from the built environment. The need to have a holistic view on emissions caused by building construction is being recognized in greater amounts. Related Project Drawdown solutions on this topic are alternative cement and building with wood. Alternative cement is a way that one of the most common building materials, cement—currently the source of 5 percent of the world’s carbon dioxide emissions—can be made more carbon efficient. Building with wood, a Project Drawdown coming attraction, is also a potentially high-impact solution to reducing building embodied emissions.

One reason why we did not apply the Passive House standard to cooling dominated climates is the large increase in embodied emissions that we estimated would occur to install insulation of such a high level. Part of this, we believe, is due to higher balance temperatures in some countries, and limited wealth in others. These, combined, result in lower use of cooling energy in the conventional case than what our data would suggest.

[1] Current adoption is defined as the amount of functional demand supplied by the solution in 2018. This study uses 2014 as the base year.

[2] All monetary values are presented in 2014 US$.

[3] Although we used the term “priority,” we do not mean to say that any solution was of greater importance than any other, but rather that for estimating total impact of all building solutions, we simply applied the impacts of some solutions before others, and used the output energy demand after application of a higher priority solution as the energy demand input to a lower priority solution.