CARBON FOOTPRINT OF MATTRESS MATERIALS: PU FOAM, STEEL AND LATEX COMPARED

This article examines the environmental impact of key materials used in mattresses (steel, PU foam, latex). It is based on a report conducted by Metsims Sustainability Consulting for EUROPUR in September 2024.

Context: Rising Sustainability Awareness

Our world is facing rising environmental challenges, including (but not limited to) climate change, land and water use, ozone depletion, and exposure to human-toxicological pollutants. Addressing these issues is essential to maintain environmental sustainability and overall quality of life. Many of the products we use daily in modern life can significantly contribute to these problems considering their full life cycle; from the extraction of raw materials and the use of chemicals to the energy-intensive industrial production processes and their end-of-life disposal.

Hence, the environmental impact of consumer products is becoming an increasingly important factor, both for consumers and manufacturers. Mattresses are no exception. Whilst comfort and price are still dominating priorities for the majority of people when deciding their next purchase, the sustainability aspect is right below, as some consumer surveys report.

How to Measure the Environmental Impact of Mattresses?

a) Life Cycle Assessment

There are several ways to measure products’ environmental impact. One globally accepted standardised methodology is the Life Cycle Assessment (LCA), a set of procedures for assessing potential environmental impacts of products or services. Yet, the data selection and methodology used can significantly influence the results and, therefore, distort the environmental perception of the materials or a product.

The two main types of an LCA analysis are cradle-to-gate and cradle-to-grave. The difference is the inclusion of the end-of-life scenarios in the latter approach. Both evaluate multiple environmental impacts (e.g., greenhouse gas emissions, water and land use, energy use, resource depletion, waste generation, etc.) from raw material extraction to the product leaving the factory.

An LCA typically includes the following impact categories:

Global Warming Potential (GWP) – Carbon footprint
Energy Use – Fossil and renewable energy consumption
Water Consumption – Water use throughout the life cycle
Acidification Potential – Contribution to acid rain formation
Eutrophication Potential – Impact on water ecosystems
Ozone Depletion Potential – Effect on the ozone layer
Photochemical Ozone Formation – Smog-forming emissions

Considering multiple environmental impact categories in an LCA is crucial because environmental issues are interconnected, and focusing on a single category can lead to unintended trade-offs. It provides a holistic understanding of environmental sustainability by evaluating multiple categories of ecological impact. This approach prevents problem shifting—where improvements in one area cause harm in another—and captures the complex interactions between environmental processes, such as how different energy sources affect various impact categories. It aligns with regulatory and stakeholder expectations for comprehensive environmental reporting and supports informed decision-making by offering a clearer, more accurate basis for evaluating and improving the sustainability of products and processes.

In essence, considering multiple impact categories in LCA ensures that sustainability assessments are balanced, scientifically robust, and aligned with long-term environmental protection goals.

b) (Product) Carbon Footprint

The downside of the LCA lies in its complexity, which can be a barrier to understanding with a wide population. A much simpler way to communicate and assess environmental impact of products is by reporting its Global Warming Potential (GWP), which only looks at one aspect – greenhouse gas emissions – of the overall life cycle assessment. In short, GWP values are used in the calculation of a Product Carbon Footprint (PCF) to express the climate change impact of different greenhouse gases in a uniform way. Experts measure GWP in kg CO₂eq per kilogram of product.

What Does “kg CO₂eq/kg” Mean?

The unit kg CO₂eq/kg stands for kilograms of CO₂ equivalent per kilogram of product. It is used to express the global warming potential (GWP) of different greenhouse gases in terms of the equivalent amount of carbon dioxide (CO₂) that would have the same climate impact over a specified time horizon (typically 100 years).

Understanding CO₂ Equivalents (CO₂eq)

Since different greenhouse gases (e.g., methane, nitrous oxide) have varying levels of warming potential, they are converted into a common unit—CO₂ equivalents (CO₂eq)—based on their Global Warming Potential (GWP). For example:

Methane (CH₄) has a GWP of 27-30, meaning 1 kg of CH₄ has the same warming effect as 27-30 kg of CO₂ over 100 years.
Nitrous Oxide (N₂O) has a GWP of 273, meaning 1 kg of N₂O is equivalent to 273 kg of CO₂.

To calculate a material’s carbon footprint, analysts sum the emissions of all relevant greenhouse gases, converting them into CO₂ equivalents, and expressing the result in kg CO₂eq/kg—which tells us how many kilograms of CO₂-equivalent emissions are released per kilogram of product produced.

For example, if a material has a carbon footprint of 2 kg CO₂eq/kg, it means that for every 1 kg of that material produced, 2 kg of CO₂-equivalent greenhouse gases are emitted into the atmosphere.

This article examines only the GWP of key mattress materials, including polyurethane PU foam, (steel) springs, and latex foam.

Key Materials in Mattresses: Summary of Environmental Impacts

Polyurethane (PU) Foam

PU foam is widely used in mattresses due to its comfort and durability. According to recent studies, there are several factors influencing the Global Warming Potential (GWP) of PU foam, including notably:

The choice of raw materials – Virgin petrochemical-based feedstocks contribute significantly to GWP, while recycled, bio-based and mass-balanced raw material can lower environmental impact
Manufacturing efficiencies – The use of renewable energy and process optimization can further reduce emissions
End-of-life impacts – Can have significant impact, especially if incinerated, highlighting the need for improved recycling practices

Steel (Springs)

Steel is commonly used in mattress spring systems, with its environmental impact varying significantly based on:

Steel type
Production technology – Steel made in electric arc furnaces (EAF) with high recycled content has a lower GWP compared to blast furnace (BF) steel.
Recycled content – Steel made with recycled content has a lower carbon footprint
Local energy sources
End-of-life treatment – Despite the high recyclability of steel, most springs enter mixed waste streams, affecting traceability and circular economy claims. In reality, closed-loop recycling is rare.

Latex Foam

Latex is often marketed as a sustainable alternative, yet its environmental impact varies:

Natural vs. synthetic latex – Natural latex has lower GWP but is less consistent in quality compared to synthetic latex.
Agricultural practices – Organic latex can exhibit lower emissions, but claims require scrutiny regarding land use changes and carbon sequestration assumptions.
End-of-life challenges – Recycling options for latex foam remain limited, and disposal methods such as incineration add significant GWP burdens.

Comparative GWP Analysis of Key Mattress Materials

Material	GWP (kg CO₂eq/kg)	Note
PU Foam	2.5 – 5.0	Variation due to recycled content and bio-based alternatives
Steel (Springs)	1.25 – 3.35	Depends on production method (BOF vs. EAF) and recycled content
Latex Foam	3.0 – 7.0	Higher values for synthetic latex; organic latex has lower impact but is less available

Understanding GWP Variability in Materials

The significant variations in GWP values are attributed to several key factors:

Polyurethane Foam (2.5 – 5.0 kg CO₂eq/kg) [source: Metsims analysis, 2024]

Lower end (2.5 kg CO₂eq/kg): Incorporates recycled polyols, bio-based polyols, or mass-balance isocyanates. Uses renewable energy sources in manufacturing.
Higher end (5.0 kg CO₂eq/kg): Produced entirely from virgin petrochemical-based feedstocks with addition of flame retardants and with no recycled content. Manufactured using high-carbon energy sources.

Steel Springs (1.25 – 3.35 kg CO₂eq/kg) [source: World Steel Association, 2023]

Lower end (1.25 kg CO₂eq/kg): Produced in an Electric Arc Furnace (EAF) using 100% recycled steel and powered by a decarbonized energy grid.
Higher end (3.35 kg CO₂eq/kg): Produced in a Blast Furnace (BF) or Basic Oxygen Furnace (BOF) with a low recycled content (~30%) and high fossil fuel usage.

Latex Foam (3.0 – 7.0 kg CO₂eq/kg) [source: Ecoinvent, 2024]

Lower end (3.0 kg CO₂eq/kg): Organic latex sourced from sustainable plantations with minimal land-use impact and low-carbon processing.
Higher end (7.0 kg CO₂eq/kg): Synthetic latex derived from petrochemicals, manufactured with energy-intensive processes and incinerated at end-of-life.

Conclusion

This article emphasizes the importance of using high-quality, specific data for LCA to make informed material choices. By leveraging high-quality LCA data and engaging in critical analysis, mattress manufacturers can make informed decisions that support both environmental goals and market competitiveness. As regulatory pressures increase and consumer demand for sustainable products grows, ensuring accurate and defendable environmental claims will be key to industry leadership.