Efficient Insulation for Energy Savings_ XPS Extruded Polystyrene Insulation Board

The energy efficiency of a building is largely determined by the materials used in its envelope. The type of insulation used is particularly important for ensuring compliance with increasingly stringent energy standards. Popular insulation materials such as XPS, PIR, PUR, and EPS each have specific qualities, and selecting the best type of insulation material for a project requires an understanding of their differences.

Different Manufacturing Processes

① What is XPS?

XPS (extruded polystyrene insulation) is manufactured using extrusion, a continuous process that results in a closed-cell structure with a smooth skin on the top and bottom of the board. XPS' closed-cell structure prevents water from penetrating the structure of the insulation board and provides long-term strength and durability.

② What is EPS?

EPS (expanded polystyrene insulation) is manufactured using beads of foam within a mould. Heat or steam is applied directly to the beads, causing them to expand and fuse together. One cubic metre of EPS contains about 10 million beads, each counting approximately 3,000 cells that are closed off and filled with air. EPS is composed of 2% polystyrene and 98% air. The manufacturing process results in a closed-cell structure, but not a closed-cell insulation board (due to voids that can occur between the beads).

③ PIR and PUR

Like XPS, PIR and PUR are closed-cell insulation materials, but chemicals are the main ingredients of PIR and PUR. These insulation products consist of foam that is inserted between two liners or facings, such as a multilayer aluminium finish or mineral fleece. On the one hand, these facings ensure that the foam stays put. On the other, they trap the gas that is responsible for the excellent lambda value characterising the PU product family.

The Thermal Conductivity of EPS, XPS, PIR, and PUR

Insulation is one of the most practical and cost-effective ways to improve a building's energy efficiency. By improving the insulation in new and existing buildings, significant cost savings and reductions in energy usage can be achieved.

Both XPS and EPS provide good thermal conductivity performance. However, the air trapped in the voids in the EPS will conduct heat. A much higher density EPS board will therefore be required to match the thermal performance of XPS insulation.

The lambda values of PIR and PUR are even better than that of XPS, allowing for very thin insulation layers. Yet when the facing that traps the foam (and the gas in the cells) is punctured or ripped, the lambda value declines.

Compressive Strength: XPS Comes Out on Top

Excellent compressive strength is a must for insulation materials in the most challenging environments, such as under slabs on a flat roof, concrete floors, foundations, plaza and podium decks, and cold storage. In general, when densities are compared, XPS has a greater compressive strength than EPS and PIR/PUR.

The compressive strength of EPS generally starts at around 70 kPa and extends to 250 kPa. Because of the way EPS is manufactured, it cannot match the higher compressive strengths of Feininger XPS 500 and Feininger XPS 700. The numbers in the latter two product names refer to CS(10\Y)500 and CS(10\Y)700: their respective compressive strengths at 10% deformation (kPa). For EPS and PIR/PUR to achieve the same compressive strength as XPS, the density of the foam would need to be increased, often resulting in a greater thickness of board.

Water Vapour Diffusion Resistance

EPS has a water vapour diffusion resistance of 30-70, whereas XPS reaches 80-250. Slightly more permeable to air and moisture, EPS is less resistant to water vapour than XPS. If you're looking to insulate a space prone to humidity (e.g. floors, cellars, and foundation walls), XPS is your best option. PIR and PUR are a no-go in those scenarios, because water may soak into the compound of the product, increasing its weight and (in the longer term) reducing its thermal value.

Applications: What is the Difference Between PIR and XPS?

The best choice of insulation material depends on individual project circumstances.

XPS has many applications. It is particularly suitable for inverted roofs, thanks to its closed-cell structure and extreme moisture-resistance. It is often used under slabs, concrete floors, foundations, and underground works due to its exceptional compressive strength.

PIR and PUR cannot be used in inverted roofs but are compatible with traditional warm roofs.

The Sustainability Question

For construction industry players who aim to build for the future, the environment is top of mind these days. PIR and PUR are chemical products that cannot be recycled, while EPS and XPS are more sustainable. EPS is made of only one material and therefore easy to recycle. XPS, too, is 100% recyclable. Moreover, the latter insulation product is manufactured with – among other ingredients – end-of-life EPS and the cutting waste of other XPS boards, making it the choice par excellence for circular construction projects and proving that plastics in construction can indeed be sustainable.

The Feininger XPS boards are manufactured with CO2 as a blowing agent instead of HFC or other chemical alternatives. This climate-friendly CO2 technology also contributes to the sustainable character of this insulation product.

Feininger XPS extruded polystyrene insulation board

Feininger is a "national high-tech enterprise", the chairman unit of XPS Association of China Plastics Association, a member unit of the National Plastics Standardization Technical Committee, a national-level three-star green building materials certification enterprise, and a national industry standard-setting unit.

Feininger has established the Engineering Technology Research Center of Polymer Physical Foaming Materials in Jiangsu Province, and has been rated as one of the top 10 extruded board enterprises in China by the Ministry of Light Industry of China for many years.

Feininger has passed ISO9001:2015, ISO14001:2015, ISO45001:2018 and strict FM certification and CE EU product standard certification. In 2016, Feininger won the United Nations "Ozone Layer Protection Recognition" honorary certificate.

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