“Practicing circular economy is like playing mahjong. What is unuseful to one player is a treasure to another.”
More than 50% of the world’s natural resources are used in the construction industry¹. Buildings and constructions use 36% of the world's energy and are responsible for 39% of the carbon footprint². In Europe, the construction industry is a big consumer of energy and waste generator: consume 50% of raw materials, 50% of energy, 30% of water and generate 30% of waste, in addition to 40% carbon emission.³ Only 3-4% of construction waste is returned to the building itself for reuse. Therefore, Netherlands, France and other countries have listed the construction industry as the primary transformation industry in their national circular economy policies.
According to the United Nations, the world’s population will reach 9.8 billion by 2050, with ⅔ of the people living in cities. How to meet this increase in demand for construction given earth’s limited resources has become an extremely important topic. Enters circular economy - circular economy can help effectively reduce the energy consumption used during construction and ensure the reuse of construction materials through circular design. At the same time, circular economy can be a new opportunity for the construction industry to upgrade.
Construction is made up of many different components, such as structure, exterior, electrical set-up, pipeline systems, even furniture or appliances. All of these parts have different life cycles, and if not planned properly, they will all have to be destroyed together, which would result in large amounts of wastes during demolition. However, if during the design phase, each level could be given the maximum amount of flexibility and was taken apart properly, then materials would no longer have to be a “depreciated” leftover, but “assets” that can be reused, which would increase its value in the future when resources become limited.
Circular buildings aim to move towards zero waste, zero emissions, and zero accidents. Consider the entire life cycle of a building or construction and plan a reversible and renewable mechanism for material, water, and energy, then it’s possible to make the best use of every resource and energy.
As the architect Ying-chao Kuo of Bio-architecture Formosana said: "Every building should be like an organism." Through the design of precast, modular and dessamble, it is possible to change components, repair, and increase components at the end of the life cycle of the building or when the building changes its function. At the same time, the value of building materials can greatly be retained and becomes the material of the next building. We can expand the levels of a building according to the different lengths of life cycle :
- The main structure of the building: the life cycle of the main structure is 50 years, and it is not uncommon for cases of more than one hundred years. Since the buildings consume a lot of resources, the strategy for the existing buildings is to extend their lifespan. While the strategy for new buildings will be to reduce the volume in design and adopt precast and modular structures to increase the reuse rate in the future.
- Exterior decoration system: the outer components to protect the building, such as exterior walls, doors and windows, roofs, etc., with a lifespan of about 20 to 30 years. Weather conditions such as wind, rain, and sunlight will directly affect the building through the exterior system for its weather resistance and its energy consumption after construction.
- Electrical and pipeline systems: the electrical equipment and pipeline configuration, such as air-conditioning, electrical, water supply and drainage, their life span is about 20 to 30 years. It is a system that is relatively variable according to user needs. The exposed conduit of the pipeline is easier to repair, replace and adjust. . If the pipeline with a shorter life span is placed in the wall with a longer life span, it is not easy to repair or replace the pipeline. It will result in shortening the life of the wall due to water leakage. Since performance will change over time, if a service-oriented business model is adopted, we will always use high-quality equipment.
- Compartment decoration system: interior walls, partitions, ceilings, floor decorations and other levels are most relevant to users. The lifespan is about ten to twenty years. It is often adjusted due to changes in user needs. Modularized Building materials increase variability and retain opportunities for reuse.
- Furniture and equipment: movable objects such as furniture, lighting, home appliances, appliances, etc., generally have a short life span. Through the adoption of a product-service-oriented business model, high-quality equipment can be enjoyed without maintenance responsibility.
Facing climate change, companies gradually view their shared responsibility for carbon reduction, and there is much room for carbon reduction in the construction industry. Taiwan’s residential and commercial sector accounts for nearly 20% of the total emissions. The high energy consumption of existing buildings makes the residential and commercial sector’s carbon emissions high, only second to the manufacturing sector. It is the department that needs to reach the largest reduction in order to reach the 2025 greenhouse gas emission reduction target. Taiwan’s construction industry has long relied on reinforced concrete (RC), which consumes more than 10 million tons of cement each year. However, the production of cement and steel are among industries with high carbon emissions. In response to future environmental trends, we should rethink the future of the entire building materials industry. In addition to the cement industry's efforts to increase the replacement rate of raw materials, Europe has also been vigorously developing technologies for recycling cement to greatly reduce the use of virgin materials. In addition, due to the development of construction technology, there are many low-carbon building materials to choose from. For example, use domestic wood from local plantations which absorb carbon dioxide during the growth and can reduce carbon emissions due to international transportation; other building materials such as bamboo and even mushrooms are developed from innovative research and development. There are many choices of green building materials, such as foamed lightweight bricks made of recycled glass, building materials made of stone sapwood. More designers and architects are required to give new life to recycled building materials from an innovative perspective.
Building Information Modeling (BIM), which has been developed by the construction industry for many years, can establish a complete material passport for a building, so that the resume and status of each building material can be clearly positioned and become a digital avatar of the building. We can treat the building as a temporary storage place for building materials. When the building has fulfilled its task, it can return the building materials or provide it for use in the next building, just like a "building materials bank."
Luxembourg-based construction company Astron worked with European banks to estimate linear and circular construction financial models. On the one hand, it is considered that the demand for parking space may change as a result of the popularization of self-driving car. On the other hand, the increasingly stringent EU carbon reduction targets and the acquisition of raw materials have become the risk of linear operation of enterprises.
Take a three-story building with 580 parking spaces as an example. In the linear mode, the wet construction method of on-site grouting is the most convenient, but after use, it can only be demolished by destructive means. The construction waste is degraded and only 8.3% of value can be recovered; while the circular building is constructed with precast modular dry construction methods. In addition to the original material cost, the cost of proper dismantling and storage after dismantling must be added. Although the cost is high, all materials are recycled and available for the next building, the value recovery is as high as 73%.
In the long run, companies can not only control assets but also obtain high return on investment. They can not only reduce the exploitation of virgin resources, risk and the consumption of raw materials and energy used in the manufacture of new building materials, can also respond to the evolution of society with higher flexibility. Circular construction is not only a "good idea, but also good business."