Collaborating with industry partners

Covestro develops customized energy efficient window solutions for “Future Buildings”

• Project initiated by the China Academy of Building Research
• Polyurethane pultrusion composite for energy efficient and fire-resistant windows
• Driving technology advancement for efficient buildings in China

Materials manufacturer Covestro has developed customized Baydur® polyurethane pultrusion window solutions as part of a future buildings program initiated by the China Academy of Building Research, in response to the Chinese government’s call for residential buildings to incorporate greater energy saving measures.

The “Experimental Platform for Energy and Environment of Future Residential Buildings” program aims to lead China’s future building technologies to ultra-low, near zero and zero energy consumption. Covestro has developed its energy saving solutions in collaboration with its partners Zhejiang Deyilong Technology Co., Ltd. and Gretsch-Unitas Group from Germany.

Regulations enforced by China’s Ministry of Housing and Urban-Rural Development have placed increasingly stringent energy and emission requirements on residential buildings across China. These measures, which necessitate the need to develop innovative low energy solutions to realize environmental sustainability have become the development focus of China’s residential building industry. Maintaining comfortable, yet sustainable, living standards is now the greatest challenge. Since the primary route of energy loss in residential buildings is via the property’s windows, developing innovative energy-saving glass materials has become a major trend in the development of green residential buildings in China.

“Innovative energy efficient window solutions are in high demand in China where energy efficiency standards for buildings are becoming increasingly stringent,” said Dr. Irene Li, Head of R&D in Asia Pacific, Business Unit Polyurethanes at Covestro. “With our global R&D capabilities and by collaborating with our partners, Covestro is committed to providing excellent and cost-effective solutions for the window industry.”

Improved window performance with innovative polyurethanes

The Baydur® polyurethane pultrusion windows developed for the “Future Buildings” project consists of a continuous fiberglass reinforced polyurethane composite with an eco-friendly waterborne polyurethane coating. The composite, which features alkali-free fiberglass as the reinforcing material and polyurethane resin as the matrix resin, is formed by a closed-mold injection and pultrusion process. This component of the glass provides the material’s thermal insulation, load-carrying and fire resistance properties. A waterborne polyurethane coating, applied to the surface of the composite profile, not only provides additional protection but also provides the opportunity to customize appearance via a range of colors and designs. Covestro, together with partners, has produced three different window solutions based on these materials to address the energy and environmental requirements of the Future Buildings program.

Covestro has produced two window designs with K values (thermal conductivity coefficient) below 1.5W/(m2•K). The “PU Casement Window - 65 Series”, which consists of an all-polyurethane profile, is suitable for various window applications. This profile offers advantages such as ultra-low heat conductivity, reliable low temperature resistance, excellent mechanical properties, and an enhanced service life. Since this material’s linear coefficient of thermal expansion resembles that of concrete, windows produced from this glass do not require a wall void to allow for differences in thermal expansion and cold contraction, preventing additional energy loss.

The “PU Bridged Casement Window - 65 Series” consists of a Covestro polyurethane profile, which acts as a thermal insulation bridge, encased within an aluminum profile. Acting as an internal insulation core, the polyurethane composite withstands the fixing force on the wall and the weight of the glass, ensuring the entire window possesses high wind pressure resistance. This series integrates both thermal insulation and enhanced load-carrying properties.

For situations where window K values lower than 0.8 are necessary, Covestro has developed the “PU Casement Window - 85 Series”, which features an all-polyurethane composite profile. This example, which meets the energy-saving requirements of “passive houses”, includes a fiberglass reinforced polyurethane profile and dual Low-E insulating glass filled with argon gas. The K value of this window model is as low as 0.77W/(m2•K). In addition, this solution adopts a special sub-frame, offering significant energy saving, corrosion resistance and waterproof sealing functions.

Meanwhile, the latest-generation eco-friendly waterborne polyurethane coatings developed by Covestro offer excellent resistance to weathering, UV exposure and aging. In addition, waterborne coatings possess excellent adhesion to glass fiber reinforced polyurethane substrates and effectively improve the smoothness of the substrate surface. Such substrates can also be widely customized, satisfying diverse requirements of surface decoration design, including metallic and matt effects or solid colors.

Covestro will enhance cooperation with local industrial value chain partners such as Deyilong, through collaborative innovation, in response to China’s increasingly stringent building requirements regarding energy efficiency and environmental protection. This progress will further help contribute to the development of China’s green building industry and the upgrade of the country’s construction industry.

About Covestro:

With 2018 sales of EUR 14.6 billion, Covestro is among the world’s largest polymer companies. Business activities are focused on the manufacture of high-tech polymer materials and the development of innovative solutions for products used in many areas of daily life. The main segments served are the automotive, construction, wood processing and furniture, and electrical and electronics industries. Other sectors include sports and leisure, cosmetics, health and the chemical industry itself. Covestro has 30 production sites worldwide and employs approximately 16,800 people (calculated as full-time equivalents) at the end of 2018.

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