As we near its 100th anniversary, expanded polystyrene (EPS) has become widely used in various industries and applications, especially in construction. Since 1970, EPS has been used in building construction due to its thermal insulation properties, lightweight closed-cell structure, durable strength, and long-term integrity. However, while these qualities make it highly useful and easy to recycle, they have also sparked debate due to recurring discussions about its degradation processes and environmental impact from various perspectives.
While the debate rages on, many improvements and alternative approaches have emerged around this material, highlighting that achieving sustainable construction involves using the right material for the right job from the outset. Thus, over time, innovations have brought new options for the recycling and use of EPS beyond traditional building applications such as infill blocks or partition panels. This demonstrates that rather than stigmatizing it as a problematic or “simple” material, it is essential to consider its qualities through design, technology, and developing methods for responsible and sustainable management.
In the past, we have seen proposals for alternative uses of EPS, such as using larvae that digest the material and whose secretions nourish a new ecosystem. Other alternatives include producing new products, such as coatings and paints. However, to understand the current landscape of expanded polystyrene, it is necessary to explore contemporary innovations along with the advances and visions that have recently emerged.
Several projects and initiatives are pioneering the application of this material with innovative design approaches and improvements in production, ranging from temporary interventions to the use of technology for enhanced characteristics. These developments highlight a clear evolution since its invention in 1929.
Ladder Street Cultural Space: A Case Study of the Use of EPS for Temporary Interventions
Nestled in the core of one of the oldest districts of Hong Kong, Ladder Street Cultural Space is part of a series of prototypes that aims to promote alternative social activities through a temporary intervention. In contrast with the regular and distinctive edges of the site, the project embraces a geometry defined by a series of circles. According to the design team, this approach creates a sense of movement and fluidity, making the spatial experience more dynamic and engaging. Facilitating smooth transitions between different areas of the space, the project generates a flexible layout that encourages visitors' exploration. The program, which includes three key functions—a community library, an exhibition space, and a seating area—aims to nurture a variety of uses and social opportunities.
Conceived as a 1:1 conceptual prototype, the project was realized using EPS panels. These panels were precisely shaped using a robotic arm equipped with a spatial hot-wire, ensuring accuracy in translating the project’s complex geometry and maintaining consistency throughout the fabrication process. Designed to incorporate a continuous sequence of holes and setbacks, the panels provide spaces to host over 200 books donated by the Chinese University of Hong Kong library.
After the installation period concludes, all materials used will be fully recycled. Specifically, the EPS panels will be recycled at the "Missing Link - Poly Foam Recycling Center" in Tsuen Wan, Hong Kong. In this regard, and according to the British Plastic Federation, the design team emphasizes that EPS can be a low-impact material. Therefore, it is important to consider that processes and proper waste management are key to its recyclability.
New Variants: Biodegradable, Fire-Retardant, and Grey Polystyrene
While traditional EPS excels in thermal and acoustic insulation for continuous insulation systems, ongoing efforts have explored ways to enhance its environmental impact, improve its properties, and tackle challenges. For instance, new variants like biodegradable polystyrene derived from agro-industrial waste and mushroom mycelium have been developed. Proposals such as these emphasize the possibility of developing circular processes around products that, under other visions, are discarded, offering an alternative to recycling processes.
In parallel, other variants have emerged, such as grey polystyrene (GPS), which contains graphite particles that significantly improve its insulation capacity over white EPS of the same thickness. Moreover, according to Construction Material Pyramid, and taking into account factors such as raw material extraction, transport, and manufacturing, GPS has a lower environmental impact (46.8 kg CO2eq/m³) than other materials such as unfired clay brick (91.8 kg CO2eq/m³) or mineral fibers such as stone fiber (68.7 kg CO2eq/m3).
Meanwhile, improvements have been developed for expanded polystyrene in adverse conditions such as fires, enhancing its characteristics through fire-retardant additives that increase its fire resistance in construction applications. This allows EPS foam insulation to meet safety requirements where wood construction is prevalent, offering enhanced protection to buildings and their occupants. When exposed to high temperatures, fire-retardant EPS does not burn but melts.
All these proposals and research demonstrate that the use and disposal of EPS extend beyond singular applications or mere waste. Transforming expanded polystyrene into innovative architectural designs and high-performance products highlights a promising pathway for integrating it into a more responsible lifecycle.
These actions underscore the importance of focusing on the environmental challenges of EPS but also its potential as a versatile resource when properly managed. Ultimately, the future of expanded polystyrene will depend on our ability to develop further technologies and practices that promote recycling and reuse, minimizing its environmental impact and maximizing its benefits in various sectors.
Credits - Ladder Street Cultural Space: Concept and Design Francesco Rossini (PI), Filipe Afonso / Project Team: Zhu Tongyun Terrie (RA), Cassone Thaik, Graça Santos / Exhibition Curators: Jimi Tsang, Michelle Chan
