A Study of the Guidelines for the Planning and Design of Circular Buildings

A Study of the Guidelines for the Planning of Abstract: Circular building is one of the key turning points in the movement of the construction industry towards sustainable development. It is a “circulation” and “human” idea aimed at balancing the construction and design of the residential environment with the responsibility and values of environmental resources and ecology. This study was focused on the formulation of planning and design guidelines that comply with the current circular building centred economy. Input from industry operatives was collected using semi-structural interviews and a pyramidal approach was employed using logical reasoning to set up planning and design objectives as well as specifications in 4 dimensions covering 12 items. The results provide substantial references for the promotion of current environmental codes compliant with circular building. They can also be used to shape up resource circulation in the construction industry, and help to meet the many needs of sustainable development in the planning and design of circular buildings.


Introduction
The circular building idea originated from the circular economy model and is now an important part of green economy. The model is in transition and is the turning point towards sustainable development. In this study attention is centered on the circular economy and includes a comprehensive analysis of a circular building environment as well as behavior. The operational factors of circular building have been extracted to create specifications focused on greenhouse gas emission and individual building service life cycles, the reduction of energy mining, and the treatment of waste as a resource. The concept of a circular economy has already penetrated trade and industry. This is especially so for construction where the share of resource consumption accounts for more than 60% of all trades combined. The first key issue is to change each type of building into a circular one. The circular building is a multi-resource circulation and integration system which centers on buildings and expands outwards to encompass building structure, construction, and decoration. It employs resources from many supply chains and has a circulation that includes many different industries. A circular building mandates circulation centered building design at the earliest planning and design stage and this plays a key role in the circulation of total environmental resources.

Circular Building
The practice of circular building involves the application of circular economics from the conception and design stages to the very end of the service life of a building. The realization of a circular economy model resides in the construction engineering do-main. It is an integral part of circular urban development and, directly and absolutely dependent on practice of the circulation model. According to a study on the essence of the circular city there are three key factors involved: a reduction of resource mining, a reduction of greenhouse gas emission throughout the renewal and recycle process, and a maximization of the recycling and reuse of material resources. In other words, waste becomes a resource [1] . Circular building is a sub item of a circular economy and a turning point and transition model from now to the final achievement of sustainable development in the future.
A circular economy changes a wasteful linear model into one with continuous recycling and a circulating supply chain [2] . In a real circular economy scientific and technological means are used to reduce the mining of limited resources to an absolute minimum; use is maximized, and extended use and reuse of resources as well as their renewal is emphasized. In processes involving the making of new goods, or their remaking by degrading, cracking, or reducing recycled resources, the circular economy also requires a reduction of the emission of harmful greenhouse gases, that the set goal of carbon neutrality should be met, and also that all loads on the environment be reduced.
In addition to the well-known green and ecological focus on the saving of energy, water, material, and land as well as the search for ecological balance in circular building, attention is also paid to the effective use of total building materials and minimizing the generation and emission of greenhouse gases, particularly when recycling and renewing material at the end of its service life. This conforms to the directives of carbon reduction against man-made global warming and natural disasters proposed by the Intergovernmental Panel on Climate Change (IPCC) of the UN which covers the carbon emission associated with buildings throughout their service lives.

Service Life by Building Design
The design and useful age of individual sections of a building are critical assessment factors. This is especially the case with the technology model, maintenance, repair, and procurement of green materials, the relevant integration system as well as construction, because together they determine the useful life of the building and total construction cost throughout its entire service life. Best practices are required at the planning and design stage to set up sustainable operation for the entire service life of the building. Different circulation, operation, and evaluation guidelines are needed to meet the goals of a circular building. In this study the recycling of substances and materials are given full consideration by reference to Stewart Brand building layering and the Locate Architect's building structure design methodology [3] . See Table 1 for useful age estimates of the major sections of a house. The structure one comes with a design age of 60 to 200 years, structural shells at 30 to 60 years, indoor furniture at 5 to 15 years (the shortest). For those with a short useful lifetime, circulation designs for different areas based on use are employed. Regarding building structure planning and design set to 60 years, the useful life of structure and material may be the same, while that of the indoor furniture and decoration may be set at 15 years. As such, the latter may go through 4 cycles of renewal and reuse relative to the building structure life cycle of 60 years. This is a critical assessment criterion for planning to recycle the building resources.

The Life Cycle of Building Projects and Work
Building work is a unique project with its own definitions, operations and scope at each stage from the beginning to the end. Figure 1 shows the operational scope of the five stages of a green building project [4] . Early stage planning and design are required to identify the root factors required to meet the conditions of the staged tasks of a circular building project. To meet the circular building goals, it is necessary that the operations relevant to circularity be taken into account. This is especially important with respect to the source and production of the building resources and the methodology, as well as their renewal, disposal, and recycling at the end of their service life. All these are required to conform to circular building conditions and also serve to extract and accumulate circular building specifications throughout the service life of the building.

The Semi-structured Interviews
In this study semi-structured interviews were held with industrial operatives and pyramidal reasoning was used to identify relevant impact factors at each stage of a circular building project for its entire service life based on operation scope definitions and individual cycles. To ensure reliable results short interviews were held and the individual specialists interviewed were chosen for their hands-on and research experience. The interviewees were experts in a range of building related fields that included: ecology, the environment, materials, civil engineering, construction, engineering management, and sustained development. All had 10 or more years of practical experience. See Figures 2 and 3 for the business functions and expertise of the 28 operatives interviewed during this study.

The Pyramid Principle
The Pyramid Principle is a logic reasoning methodology developed at the McKinsey consultancy by Barbara Minto and is based on the tiered analysis theory of the Pyramid Principle featuring top-down reasoning along a logical line. The argument for the top layer is the effect of the one below, while the lower layer is the cause of the upper layer [5] . This study identifies the planning and design guidelines for circular building by analyzing their requirements in terms of the four elements of the Pyramid Principle: Situation, Complication, Question, and Answer. Individual guidelines of this study were aimed at the core target of circulation and were suitable for "conclusion oriented" logical reasoning and inductive argument. Each dimension was viewed as a system for reasoning. Guidelines were independent from one another. The upper dimension was the inductive conclusion of the one below. The study and analysis process was aimed at identification of the core of the guidelines supporting the dimension to ensure that the reasoning satisfies the nature of circular building with respect to less resource mining and greenhouse gas emission as well as an improvement in the rate of recycling and reuse.
Vertical logic reasoning using the Pyramid Principle was used, as shown in Figure 4. Goals of operation at each layer were the conclusion of arguments of the one below and also supported the layer above. "The essential circular building target" on the top of the pyramid was the final convergent goal of this study and the top-down logic reasoning. Arguments were sorted by logical order and  To support the ultimate goal, the arguments for each layer had to be associated with the essence of circular building and satisfy its root requirements. Figure 5 is a flowchart of the implementation of resources suitable for recycling by an analysis of the circulation of materials at individual stages during the service life of a building project. For example, at the operation and maintenance stage, maintenance, servicing, and retrofitting measures can be used to keep resources or equipment of individual building sections at normal operation performance and capacity. At end of their service life, they can be reworked or transferred to other suppliers for re-use or remaking by decomposition, cracking, or reduction through the circulation supply chain. Resources that have reusable value can be sold to second-hand dealers or leasing outlets after being sorted or retrofitted.

Study and Analysis
The material flow diagram for a circular building is shown in Figure 6. An analysis is shown of the circulation and certification operations carried out at each stage. For example, at the operation and maintenance stage, any materials suitable for recycling, reuse, and renewal can be collected, treated, serviced, and retrofitted for another building. During construction, a circular building requires the use of recyclable and reusable materials as well as the purchase of C2C certified material. The material circulation cycle in circular building construction is aimed at conformance with the circular economy model and at a search for solutions to problems.
After the last stage has been reached the analysis of circular building material flow is used to formulate guidelines for execution. Most operatives interviewed agreed that the planning and design of a circular building project was the key, see  The project construction stage focuses on practice. In addition to adherence to the design guidelines, it is necessary to detail design and construction and to make sure materials used in all parts of the building comply with green production, are durable, can be recycled and reused, and meet the designed useful life of components in each section.

Results
This study came up with 12 guidelines based on the Pyramid Principle "conclusion orientation". This was achieved by reasoning from the four indicators A, B, C, and D. See Table 2

Conclusions
Global warming is accelerating climate change far beyond the estimates by scientists around the world. The share of material resource consumption and emission of greenhouse gas by construction accounts for 50 to 60% of the total. This mandates the transformation of conventional buildings into circular ones. A feasible circular building guideline is a must for the construction industry to effectively ease the load on the resource environment. This study presents a set of 12 circular building guidelines with 4 goals based on the definition of the operational scope and the life cycle of a building. In addition, it presents a clear picture of the nature of the circular economy and not only covers the basic operations of resource recycling and renewal, but also focuses on the reduction of resource consumption, greenhouse gas emission, and the chain of resource circulation. The main contribution made by this study lies in the guidelines for the planning and design of a circular building. These are a practical and feasible reference for those engaged in the planning and design, as well as the assessment of circular buildings.