Extract

INTRODUCTION:
Waste generated through the renovation and demolition of buildings makes up more than forty percent of international waste volumes. Buildings are prone to producing waste due to the way in which materials are joined together, and due to the highly bespoke nature of many building components. To address these issues there is an urgent need to implement circular economy-based building methods. The circular economy (circularity) asks designers and product specifiers to implement fixing methods, materials, and architectural details that either facilitate high-value material recycling or direct material recovery and reuse. Implementing such details in a building is complicated by performance requirements, economics, aesthetic requirements, and the availability of appropriate materials. It was the aim of this research to build upon earlier attempts to introduce circular building details into light-timber framed construction systems. The study took principles from circular design theory and critical evaluations of earlier proposed solutions to create a new circular construction system. The research differentiated itself from earlier studies through the focus on the connections between adjoining material layers.

METHODS:
The research adopted an action research methodology that incorporated the planning, designing, building and evaluation of multiple prototype circular economy buildings. The cyclic nature of action research allowed for a design refinement process to take place in which each new prototype design built upon the lessons learned from earlier prototypes. Four major prototyping cycles were undertaken with each resulting in the construction of a full scale ‘permanent’ structure. During the design of each prototype structural and functional evaluations were undertaken (against industry standards). After the construction of each prototype economic and circular evaluations were carried out. The circular assessment was based on reoccurring circular design criteria found in literature.

RESULTS:
The study identified several highly effective methods that facilitate material circularity in light-timber framed construction. The creation of a structurally independent and resilient frame comprised of standardised parts was validated as being essential for circular construction. A cladding and environmental control system that met the requirements of circularly was also developed. Gasket based reusable sheathing (rigid air barrier) sealing details were developed alongside a reversible cladding fixing interface for cavity-based construction/finishing. Together these systems unlock a significant proportion of the materials within a buildings envelope for reuse.

CONCLUSIONS:
The implementation of construction methods that meet the requirements of circularity are becoming ever more important as the sector transitions to a low carbon and low impact operating model. While this study addressed some of the key traditional barriers to the implementation of circularity in construction there remains significant opportunity for further innovative circular construction research and solutions.

PDF

Download