The most common components in building envelopes play an important role, but they do not always reach their true potential. To this end, various types of plastic materials can help building owners achieve the efficiency they need. For example, due to the manufacturing method of polystyrene boards, extruded polystyrene (XPS) foam insulation sheathing has many advantages. Energy-saving, easy to install, lightweight and identifiable in blue, pink or green, the specifications of extruded polystyrene foam sheathing may allow a single product to form continuous insulation and moisture barrier walls on buildings, thereby helping to improve energy efficiency.
Manufacturing extruded polystyrene
Extruded polystyrene foam board insulation material starts with solid particles of polystyrene resin. Plastic pellets are fed into an extruder where they are melted and mixed with key additives to form a viscous fluid. Next, a blowing agent is injected to expand the plastic product. Under carefully controlled heat and pressure conditions, the plastic mixture is forced through a die to form the desired shape. The rigid foam plastic is then trimmed into product sizes of 1800×600mm, commonly considered boards.
This continuous process produces a closed-cell structure that looks like a uniform mass of bubbles with common walls between them. The top and bottom also form continuous smooth surfaces.
The closed-cell structure of extruded polystyrene foam has excellent long-term strength and durability. The product has a variety of compressive strengths to meet different application needs. Due to its inherent physical properties, this strength does not depend on the use of finishes or laminates, which can sometimes be affected during installation. However, when specified for specific applications, extruded polystyrene foam finish products can be used to add additional strength. Extruded polystyrene plastic also comes in a variety of sizes, with thicknesses up to 100 mm, to accommodate multiple applications.
Energy efficiency of polystyrene boards
When used in residential buildings, extruded polystyrene foam sheathing has positive energy and air emission advantages. According to a 2000 study, over the 50-year service life of a building, the energy saved by the correct use of XPS foam insulation is much more than the energy consumed to manufacture the insulation. 1 Another study presented at the 2004 Building Technology Forum showed that in less than three years, greenhouse gas emissions avoided due to heating/cooling energy consumption exceeded those during the manufacturing of extruded polystyrene foam insulation sheathing. Therefore, energy saving can also be another means of environmental protection. Correctly installed XPS foam can also improve building energy efficiency by providing a complete insulation layer on the walls. This reduces air movement through the walls, which can take away energy. Insulation between studs does not necessarily provide complete insulation value, because wood studs and other framing members are not insulated. This phenomenon is called thermal bridging and can significantly reduce the thermal performance of a building.
Since residential framing typically accounts for about 25% of wall area (considering door and window frames), when only cavity insulation is used, a quarter of the wall is non-insulated. Therefore, extruded polystyrene foam sheathing can provide insulation value for the entire wall area. In addition to its inherent insulation properties, XPS foam sheathing, when properly installed and seam-taped, can also greatly reduce air leakage through walls, thereby improving energy efficiency and comfort.
A fundamental attribute of sustainable building products, especially insulation materials, is the ability to function properly during their service life without degrading physical performance. In fact, properly designing a building's heating and air conditioning systems requires good long-term insulation performance.
Extruded polystyrene foam also has advantages because it can help manage moisture, resist water absorption and freeze-thaw cycles. When traditional insulation materials absorb water, their thermal performance will be impaired over time.
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